安卓开发基础期末考试知识点总结
1. 布局
- 线性布局
//线性布局以水平或垂直方式来显示界面中的控件
//orientation属性设置垂直或水平
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:orientation="vertical"
>
</LinearLayout>
- 表格布局
//通过表格来管理内部组件位置
<?xml version="1.0" encoding="utf-8"?>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:stretchColumns="0,3" //相当于设置表格四列
android:gravity="center_vertical" //表格整体居中
android:background="#bf66ff" //设置背景颜色
>
//添加若干行
<TableRow>
//添加若干组件，span设置是否跨列
<TextView android:layout_span="4" />
</TableRow>
</TableLayout>
- 约束布局
一种可视化方式编写方式，直接拖动组件即可
2. 基本组件
- 单选按钮
//单选按钮的页面样式
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:orientation="vertical"
android:background="#bf66ff"
>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="您的性别是："/>
<RadioGroup
android:id="@+id/sex"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<RadioButton
android:id="@+id/man"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="男"
android:checked="true"/> //设置默认选中 男
<RadioButton
android:id="@+id/woman"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="女"/>
</RadioGroup>
</LinearLayout>
//单选按钮的事件监听
public void onClick(View view){
RadioGroup radioGroup = findViewById(R.id.sex);
for(int i=0;i<radioGroup.getChildCount();i++){
RadioButton radioButton = (RadioButton) radioGroup.getChildAt(i);
if(radioButton.isChecked()){
Toast.makeText(MainActivity.this,"您点击了"+radioButton.getText(),Toast.LENGTH_SHORT).show();
break;//因为是单选，所以可以直接退出循环
}
}
}
- 多选按钮
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:orientation="vertical"
android:background="#bf66ff"
>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="您的爱好有："/>
<CheckBox
android:id="@+id/love1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="篮球"/>
<CheckBox
android:id="@+id/love2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="足球"/>
<CheckBox
android:id="@+id/love3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="羽毛球"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="提交"
android:onClick="onClick"/>
</LinearLayout>
//多选按钮监听
public void onClick(View view){
CheckBox checkBox1 = findViewById(R.id.love1);
CheckBox checkBox2 = findViewById(R.id.love2);
CheckBox checkBox3 = findViewById(R.id.love3);
String str = "您的爱好有：";
if(checkBox1.isChecked()) str+=checkBox1.getText()+" ";
if(checkBox2.isChecked()) str+=checkBox2.getText()+" ";
if(checkBox3.isChecked()) str+=checkBox3.getText()+" ";
Toast.makeText(MainActivity.this,str,Toast.LENGTH_SHORT).show();
}
- ImageView
用于图像放置
- ImageSwitcher
图像切换并可以产生动画效果
- 实现一个图片浏览器
//布局
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<ImageView
android:id="@+id/images"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:src="@mipmap/zhifubao"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="95dp" />
</androidx.constraintlayout.widget.ConstraintLayout>
//功能实现
package com.example.tupianliulanqi;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
public class MainActivity extends AppCompatActivity {
int count =-1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final int[] images = new int[]{R.mipmap.zhifubao,R.mipmap.weixin,R.mipmap.mmm};
final ImageView imageView = findViewById(R.id.images);
imageView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(count>=images.length-1) count=-1;
imageView.setImageResource(images[++count]);
}
});
}
}
- SeekBar
拖动条，用户操作控制
- RatingBar
评分条，一般用于对产品的评价或服务满意度评价，用户操作
- 用SeekBar（拖动条）和RatingBar（评分条）改变图片的透明度(要求同步）
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<ImageView
android:id="@+id/image"
android:layout_width="0dp"
android:layout_height="280dp"
android:layout_marginStart="31dp"
android:layout_marginLeft="31dp"
android:layout_marginEnd="31dp"
android:layout_marginRight="31dp"
android:layout_marginBottom="40dp"
android:src="@mipmap/ic_launcher"
app:layout_constraintBottom_toTopOf="@+id/seekBar"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<SeekBar
android:id="@+id/seekBar"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="226dp"
android:max="255"
android:progress="255"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<RatingBar
android:id="@+id/ratingBar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="31dp"
android:numStars="5"
android:rating="5"
android:stepSize="0.5"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/seekBar" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="20dp"
android:layout_marginLeft="20dp"
android:text="当前图片透明度为："
app:layout_constraintBaseline_toBaselineOf="@+id/alpha"
app:layout_constraintStart_toStartOf="@+id/ratingBar" />
<TextView
android:id="@+id/alpha"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="34dp"
android:text="透明度"
app:layout_constraintStart_toEndOf="@+id/textView"
app:layout_constraintTop_toBottomOf="@+id/ratingBar" />
</androidx.constraintlayout.widget.ConstraintLayout>
package com.example.tupiantoumingdu;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.RatingBar;
import android.widget.SeekBar;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final ImageView imageView = findViewById(R.id.image);
final SeekBar seekBar = findViewById(R.id.seekBar);
final RatingBar ratingBar = findViewById(R.id.ratingBar);
final TextView textView = findViewById(R.id.alpha);
//拖动条监听方法setOnSeekBarChangeListener
seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
imageView.setAlpha(i); //透明度的最大值为255，所以直接用i
ratingBar.setRating(i/51); //只有五颗星，所以除以51
textView.setText(i+""); //这里的i必须为字符串类型
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
ratingBar.setOnRatingBarChangeListener(new RatingBar.OnRatingBarChangeListener() {
@Override
public void onRatingChanged(RatingBar ratingBar, float v, boolean b) {
imageView.setAlpha((int)v*51);
seekBar.setProgress((int)v*51);
textView.setText(v*51+"");
}
});
}
}
3. 易考题
- ListView
定义一个ListView，用SimpleAdapter为其添加内容，要求每个表项显示一本书的封面图像，书名，内容简介；为其添加单击事件监听，在单击时显示书的作者信息
//layout.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ListView
android:id="@+id/listView"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</ListView>
</LinearLayout>
//main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:orientation="horizontal">
<ImageView
android:id="@+id/img"
android:layout_width="100dp"
android:layout_height="100dp"
android:paddingLeft="10dp"
/>
<TextView
android:id="@+id/textView"
android:layout_width="100dp"
android:layout_height="100dp"
android:textAlignment="center"
android:gravity="center"
android:text="简介"
android:layout_marginLeft="20dp"
/>
<TextView
android:id="@+id/textView1"
android:layout_width="100dp"
android:layout_height="100dp"
android:textAlignment="center"
android:gravity="center"
android:text="介绍"
android:layout_marginLeft="20dp"
/>
</LinearLayout>
//MainActivity.java
package com.example.listview;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//注意，这里一定要改为listview的布局
super.setContentView(R.layout.layout);
ListView listView = findViewById(R.id.listView);
final String[] writer = new String[]{"马化腾","马云","曾强"};
final String[] info = new String[]{"微信，移动社交软件","支付宝，移动支付，方便快捷","帅气大方绅士高尚"};
final int[] imgs = new int[]{R.mipmap.weixin,R.mipmap.zhifubao,R.mipmap.mmm};
List<Map<String,Object>> listItem = new ArrayList<>();
for(int i=0;i<writer.length;i++){
Map<String,Object> map = new HashMap<>();
map.put("img",imgs[i]);
map.put("writer",writer[i]);
map.put("info",info[i]);
listItem.add(map);
}
SimpleAdapter simpleAdapter = new SimpleAdapter(this,listItem,R.layout.activity_main,
new String[]{"img","writer","info"},new int[]{R.id.img,R.id.textView,R.id.textView1});
listView.setAdapter(simpleAdapter);
//listview项目监听
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Toast.makeText(MainActivity.this,writer[i],Toast.LENGTH_SHORT).show();
}
});
}
}
- 通知
package com.example.tongzhi;
import androidx.appcompat.app.AppCompatActivity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button = findViewById(R.id.send);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//创建一个notification对象
Notification.Builder notification = new Notification.Builder(MainActivity.this);
//打开通知，通知自动消失
notification.setAutoCancel(true);
//设置消息图标
notification.setSmallIcon(R.mipmap.ic_launcher);
notification.setContentTitle("通知标题");
notification.setContentText("通知提示文本");
//设置提示方式
notification.setDefaults(Notification.DEFAULT_SOUND);
//设置发送时间
notification.setWhen(System.currentTimeMillis());
//创建启动activity的Intent对象
Intent intent = new Intent(MainActivity.this, Message.class);
PendingIntent pendingIntent = PendingIntent.getActivity(MainActivity.this,0,intent,0);
//设置通知栏点击跳转
notification.setContentIntent(pendingIntent);
//获取通知管理器
NotificationManager notificationManager = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
Toast.makeText(MainActivity.this,"test",Toast.LENGTH_SHORT).show();
notificationManager.notify(0x11,notification.build());
}
});
}
}
- 对话框
package com.example.duihuakuang;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button = findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
AlertDialog alertDialog = new AlertDialog.Builder(MainActivity.this).create();
alertDialog.setIcon(R.mipmap.ic_launcher);
alertDialog.setTitle("对话框标题");
alertDialog.setMessage("对话框的内容");
alertDialog.setButton(DialogInterface.BUTTON_NEGATIVE, "取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
Toast.makeText(MainActivity.this,"取消",Toast.LENGTH_SHORT).show();
}
});
alertDialog.setButton(DialogInterface.BUTTON_POSITIVE, "确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
Toast.makeText(MainActivity.this,"确定",Toast.LENGTH_SHORT).show();
}
});
alertDialog.show();
}
});
}
}
- 多Activity,并用Bundle传递数据
//main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<EditText
android:id="@+id/str1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="56dp"
android:hint="str1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/btn"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="提交"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/str1" />
</androidx.constraintlayout.widget.ConstraintLayout>
//main2.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Main2Activity">
<TextView
android:id="@+id/result"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:text="返回结果"/>
<Button
android:id="@+id/back"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="64dp"
android:text="返回"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
//main.java
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button = findViewById(R.id.btn);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String str = ((EditText)findViewById(R.id.str1)).getText().toString();
Intent intent = new Intent(MainActivity.this,Main2Activity.class);
Bundle bundle = new Bundle();
bundle.putCharSequence("str",str);
intent.putExtras(bundle);
startActivity(intent);
}
});
}
}
//main2.java
public class Main2Activity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
Intent intent = getIntent();
Bundle bundle = intent.getExtras();
TextView textView = findViewById(R.id.result);
String str = bundle.getString("str");
textView.setText(str);
Button button = findViewById(R.id.back);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
finish();
}
});
}
}
- 菜单
添加菜单，并为菜单添加单击事件，在选择菜单项后改变背景色
//在res目录下创建目录menu,并编写一个menu.xml，代码如下：
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@+id/red" android:title="红色"/>
<item android:id="@+id/green" android:title="绿色"/>
</menu>
//activity
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu1,menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(@NonNull MenuItem item) {
TextView textView = findViewById(R.id.color);
switch (item.getItemId()){
case R.id.red:
textView.setText("红色");
textView.setBackgroundColor(Color.parseColor("#ff0000"));
break;
case R.id.green:
textView.setText("绿色");
textView.setBackgroundColor(Color.parseColor("#00ff00"));
break;
}
return super.onOptionsItemSelected(item);
}
}
- Fragment（重点）
1. 静态Fragment设置标题和内容
- 创建两个fragment，设置布局文件
//fragment_title.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="50dp"
android:id="@+id/TitleFragment"
tools:context=".titleFragment"
android:orientation="horizontal">
<ImageView
android:id="@+id/logo"
android:layout_width="50dp"
android:layout_height="30dp"
android:layout_centerVertical="true"
android:paddingLeft="10dp"
android:scaleType="centerCrop"
android:src="@mipmap/ic_launcher"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="标题"
android:textSize="27sp"
android:textColor="#ff00ff"/>
</RelativeLayout>
//fragment_content.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".contentFragment">
<!-- TODO: Update blank fragment layout -->
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="内容"
android:gravity="center"
android:textSize="30sp"
android:textColor="#ffff00"/>
</LinearLayout>
- 初始化Fragment，需要重写onCreateView()方法
//titleFragment.java
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_title, null);
RelativeLayout layout = view.findViewById(R.id.TitleFragment);
layout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(getActivity(),"您单击呢标题",Toast.LENGTH_SHORT).show();
}
});
return view;
}
//contentFragent.java
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_content, null);
}
注意：如果最终运行结果闪退，则需要注释掉如下代码：
/* @Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}*/
- 最后，在主布局文件中引入各个fragment
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<fragment
android:id="@+id/fragment_title"
android:layout_width="match_parent"
android:layout_height="50dp"
android:name="com.example.fragment.titleFragment"/>
<fragment
android:id="@+id/fragment_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:name="com.example.fragment.contentFragment"/>
</RelativeLayout>
注意：不要忘了修改配置文件，去除程序默认的标题显示
android:theme="@style/Theme.AppCompat.DayNight.NoActionBar
2. 动态Fragment
实现模拟底部导航切换界面
1. 编写两个页面的内容部分
//这里用上面的fagment_title.xml来代替第一个页面
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/TitleFragment"
tools:context=".titleFragment"
android:orientation="horizontal">
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:layout_centerInParent="true"
android:text="这是主页"
android:textSize="27sp"
android:textColor="#ff00ff"/>
</RelativeLayout>
//第二个页面内容fragment_content.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/ContentFragment"
tools:context=".contentFragment">
<!-- TODO: Update blank fragment layout -->
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="第二页"
android:layout_gravity="center"
android:layout_centerInParent="true"
android:gravity="center"
android:textSize="30sp"
android:textColor="#ffff00"/>
</RelativeLayout>
2. 编写主活动代码
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private FragmentManager manager;
private FragmentTransaction transaction;
private RadioButton radioButton1;
private RadioButton radioButton2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
manager = getSupportFragmentManager();
transaction = manager.beginTransaction();
transaction.add(R.id.id_content,new titleFragment());
transaction.commit();
initView();
}
private void initView(){
radioButton1 = findViewById(R.id.bar1);
radioButton2 = findViewById(R.id.bar2);
radioButton1.setOnClickListener(this);
radioButton2.setOnClickListener(this);
}
@Override
public void onClick(View view) {
transaction = manager.beginTransaction();
switch (view.getId()){
case R.id.bar1:
transaction.replace(R.id.id_content,new titleFragment());
break;
case R.id.bar2:
transaction.replace(R.id.id_content,new contentFragment());
break;
}
transaction.commit();
}
}
3. 用fragment分两步实现登录功能，要求能够回退，解决重屏问题
- 解决重屏
<activity android:name=".MainActivity"
android:configChanges="orientation|keyboardHidden|screenSize">
- 编写2个fragment布局代码和主布局代码
//main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<FrameLayout
android:id="@+id/content"
android:layout_width="match_parent"
android:layout_height="match_parent"></FrameLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
//login1.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Login1Fragment"
>
<TableLayout
android:layout_gravity="center"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:stretchColumns="0,3">
<TableRow>
<TextView />
<TextView
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:text="用户名"/>
<EditText
android:id="@+id/username"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:hint="请输入用户名"/>
<TextView />
</TableRow>
<TableRow>
<TextView />
<Button
android:id="@+id/username_btn"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="下一步"
android:layout_span="2" />
<TextView />
</TableRow>
</TableLayout>
</FrameLayout>
//login2.xml同上
- 编写fragment代码
//首先，两个fragment都要实现View.OnClickListener，并重写onClick()方法
public class Login1Fragment extends Fragment implements View.OnClickListener
//Login1Fragment.java
private String username;
public String getUsername() {
return username;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_login1, container, false);
Button btn = view.findViewById(R.id.username_btn);
final EditText editText = view.findViewById(R.id.username);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
username = editText.getText().toString();
if(getActivity()instanceof OnFragmentInteractionListener){
((OnFragmentInteractionListener) getActivity()).onBtnNextClick();
}
}
});
return view;
}
@Override
public void onClick(View view) {
}
public interface OnFragmentInteractionListener{
void onBtnNextClick();
}
//Login2Fragment.java
private String password;
public String getPassword() {
return password;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_login2, container, false);
Button btn = view.findViewById(R.id.password_btn);
final EditText editText = view.findViewById(R.id.password);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
password = editText.getText().toString();
if(login2FragmentListener!=null){
login2FragmentListener.btnNext2Click();
}
}
});
return view;
}
public interface Login2FragmentListener{
void btnNext2Click();
}
private Login2FragmentListener login2FragmentListener;
public void setLogin2FragmentListener(Login2FragmentListener login2FragmentListener) {
this.login2FragmentListener = login2FragmentListener;
}
@Override
public void onClick(View view) {
}
- 主活动方法
//需要先实现两个fragment的接口
public class MainActivity extends AppCompatActivity implements Login1Fragment.OnFragmentInteractionListener,Login2Fragment.Login2FragmentListener{
private Login1Fragment login1Fragment;
private Login2Fragment login2Fragment;
private String username;
private String password;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
login1Fragment =new Login1Fragment();
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.add(R.id.content,login1Fragment);
transaction.commit();
}
@Override
public void onBtnNextClick() {
username = login1Fragment.getUsername();
login2Fragment = new Login2Fragment();
login2Fragment.setLogin2FragmentListener(this);
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.hide(login1Fragment);
transaction.add(R.id.content,login2Fragment);
transaction.addToBackStack(null);
transaction.commit();
}
@Override
public void btnNext2Click() {
password = login2Fragment.getPassword();
Toast.makeText(getApplication(),"用户名："+username+"，密码："+password,Toast.LENGTH_SHORT).show();
}
}
- 数据库管理
使用数据库完成对用户的增删改查
1. 实体类
package com.example.shujuku;
public class User {
private String username;
private String password;
private String address;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
2. 数据库和表的创建管理器
//UserDbHelper.java
package com.example.shujuku;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class UserDbHelper extends SQLiteOpenHelper {
private final static int DB_VERSION = 1;
private final static String DB_NAME = "user.db";
public final static String TABLE_NAME = "user";
public UserDbHelper(Context context){
super(context,DB_NAME,null,DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
String sql = "create table if not exists "+TABLE_NAME+"(username text primary key,password text,address text)";
sqLiteDatabase.execSQL(sql);
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
String sql = "drop table if exists "+TABLE_NAME;
sqLiteDatabase.execSQL(sql);
onCreate(sqLiteDatabase);
}
}
3. 数据库操作类UserDao
//UserDao.java
package com.example.shujuku;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import java.util.ArrayList;
import java.util.List;
public class UserDao {
private UserDbHelper userDbHelper;
private Context context;
private SQLiteDatabase db;
public UserDao(Context context){
this.context = context;
userDbHelper = new UserDbHelper(context);
}
/**
* 插入用户
* @param user
*/
public void insert(User user){
db = userDbHelper.getWritableDatabase();
db.beginTransaction();
ContentValues contentValues = new ContentValues();
contentValues.put("username",user.getUsername());
contentValues.put("password",user.getPassword());
contentValues.put("address",user.getAddress());
db.insertOrThrow(userDbHelper.TABLE_NAME,null,contentValues);
db.setTransactionSuccessful();
db.endTransaction();
}
/**
* 查找所有得用户
* @return
*/
public List<User> findAll(){
ArrayList<User> users = new ArrayList<>();
db = userDbHelper.getReadableDatabase();
Cursor cursor = db.query(userDbHelper.TABLE_NAME,
null,null,null,null,null,null);
cursor.moveToFirst();
while(!cursor.isAfterLast()){
User user = new User();
String username = cursor.getString(0);
String password = cursor.getString(1);
String address = cursor.getString(2);
user.setUsername(username);
user.setPassword(password);
user.setAddress(address);
users.add(user);
cursor.moveToNext();
}
return users;
}
/**
* 根据用户名删除用户
* @param username
*/
public void deleteStudentByUserName(String username){
db = userDbHelper.getWritableDatabase();
db.beginTransaction();
String sql = "delete from "+UserDbHelper.TABLE_NAME+" where username ="+"'"+username+"'";
db.execSQL(sql);
db.setTransactionSuccessful();
db.endTransaction();
}
/**
* 根据用户名修改用户信息
* @param user
* @param username
*/
public void update(User user ,String username){
db = userDbHelper.getWritableDatabase();
db.beginTransaction();
ContentValues contentValues = new ContentValues();
contentValues.put("username",user.getUsername());
contentValues.put("password",user.getUsername());
contentValues.put("address",user.getAddress());
db.update(UserDbHelper.TABLE_NAME,contentValues,"username='"+username+"'",null);
db.setTransactionSuccessful();
db.endTransaction();
}
}
4. 主方法类（实现各个功能页面的跳转）
//main.java
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button add_user = findViewById(R.id.add_user);
add_user.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this,AddUserActivity.class);
startActivity(intent);
}
});
Button find_user = findViewById(R.id.find_user);
find_user.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this,FindUserActivity.class);
startActivity(intent);
}
});
Button delete_user = findViewById(R.id.delete_user);
delete_user.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this,DeleteUserActivity.class);
startActivity(intent);
}
});
Button update_user = findViewById(R.id.update_user);
update_user.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this,UpdateUserActivity.class);
startActivity(intent);
}
});
}
}
5. 4个功能方法调用userdao实现增删改查
//增加用户
userDao = new UserDao(this);
Button add_btn = findViewById(R.id.add_btn);
add_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
EditText editText1 = findViewById(R.id.username);
EditText editText2 = findViewById(R.id.password);
EditText editText3 = findViewById(R.id.address);
String username = editText1.getText().toString();
String password = editText2.getText().toString();
String address = editText3.getText().toString();
User user = new User();
user.setUsername(username);
user.setPassword(password);
user.setAddress(address);
userDao.insert(user);
TextView textView = findViewById(R.id.result);
textView.setText("插入成功");
}
});
//删除用户
Button delete_btn = findViewById(R.id.delete_btn);
delete_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
EditText editText = findViewById(R.id.delete_username);
String username = editText.getText().toString();
userDao = new UserDao(DeleteUserActivity.this);
userDao.deleteStudentByUserName(username);
Toast.makeText(getApplication(),"删除成功!",Toast.LENGTH_SHORT).show();
}
});
//修改用户
Button update_btn = findViewById(R.id.update_btn);
update_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
userDao = new UserDao(UpdateUserActivity.this);
EditText editText = findViewById(R.id.prev_username);
EditText editText1 = findViewById(R.id.update_username);
EditText editText2 = findViewById(R.id.update_password);
EditText editText3 = findViewById(R.id.update_address);
String username = editText.getText().toString();
String update_username = editText1.getText().toString();
String update_password = editText2.getText().toString();
String update_address = editText3.getText().toString();
User user = new User();
user.setUsername(update_username);
user.setPassword(update_password);
user.setAddress(update_address);
userDao.update(user,username);
Toast.makeText(getApplication(),"修改成功",Toast.LENGTH_SHORT).show();
}
});
//查看所有用户
Button find_btn = findViewById(R.id.find_btn);
find_btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
TableLayout tableLayout = findViewById(R.id.tableLayout);
TableRow tableRow = new TableRow(FindUserActivity.this);
TextView textView = new TextView(FindUserActivity.this);
textView.setText("用户名");
tableRow.addView(textView);
TextView textView1 = new TextView(FindUserActivity.this);
textView1.setText("密码");
tableRow.addView(textView1);
TextView textView2 = new TextView(FindUserActivity.this);
textView2.setText("地址");
tableRow.addView(textView2);
tableLayout.addView(tableRow);
userDao = new UserDao(FindUserActivity.this);
List<User> users = userDao.findAll();
for(int i=0;i<users.size();i++){
TableRow tableRow1 = new TableRow(FindUserActivity.this);
TextView text1 = new TextView(FindUserActivity.this);
text1.setText(users.get(i).getUsername());
tableRow1.addView(text1);
TextView text2 = new TextView(FindUserActivity.this);
text2.setText(users.get(i).getPassword());
tableRow1.addView(text2);
TextView text3 = new TextView(FindUserActivity.this);
text3.setText(users.get(i).getAddress());
tableRow1.addView(text3);
tableLayout.addView(tableRow1);
}
}
});
6. 页面布局代码，略
- 服务
用服务完成两个随机数的加法操作
//main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:orientation="vertical"
android:gravity="center">
<Button
android:id="@+id/open"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="绑定服务"/>
<Button
android:id="@+id/cannel"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="取消绑定"/>
<Button
android:id="@+id/run"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="运行服务"/>
<TextView
android:id="@+id/result"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="结果"/>
</LinearLayout>
//MyService.java
package com.example.service;
import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
import android.widget.Toast;
public class MyService extends Service {
private IBinder iBinder = new localBinder();
public class localBinder extends Binder{
MyService getService(){
return MyService.this;
}
}
public MyService() {
}
@Override
public IBinder onBind(Intent intent) {
Toast.makeText(this,"绑定成功",Toast.LENGTH_SHORT).show();
return iBinder;
}
@Override
public boolean onUnbind(Intent intent) {
Toast.makeText(this,"取消绑定成功",Toast.LENGTH_SHORT).show();
return super.onUnbind(intent);
}
//生成随机数
public double getRandomNumber(){
double x = Math.random()*100;
return x;
}
public double jisuan(double x,double y){
return x+y;
}
}
//mian.java
public class MainActivity extends AppCompatActivity {
private MyService myService;
private ServiceConnection conn = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
myService = ((MyService.localBinder) iBinder).getService();
}
@Override
public void onServiceDisconnected(ComponentName componentName) {
myService = null;
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btn_open = findViewById(R.id.open);
btn_open.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(myService==null){
Intent intent = new Intent(getApplication(),MyService.class);
bindService(intent,conn,BIND_AUTO_CREATE);
}
}
});
Button btn_cannel = findViewById(R.id.cannel);
btn_cannel.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
unbindService(conn);
}
});
Button run = findViewById(R.id.run);
run.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
TextView result = findViewById(R.id.result);
double sum = myService.jisuan(myService.getRandomNumber(),myService.getRandomNumber());
result.setText(sum+"");
}
});
}
}
- 广播
使用广播监听网络状态
页面布局略
//MyReceiver.java
package com.example.guangbo;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.Network;
import android.net.NetworkInfo;
import android.widget.Toast;
public class MyReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
if(isNetwork(context)){
Toast.makeText(context,"网络连接",Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(context,"断开连接",Toast.LENGTH_SHORT).show();
}
}
public interface NetWorkInfoInterface{}
private NetWorkInfoInterface netWorkInfoInterface;
public void getNetWorkInfo(MainActivity netWorkInfoInterface){
this.netWorkInfoInterface = netWorkInfoInterface;
}
public boolean isNetwork(Context context){
ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(context.CONNECTIVITY_SERVICE);
Network[] networks = connectivityManager.getAllNetworks();
NetworkInfo networkInfo;
for(Network network:networks){
networkInfo = connectivityManager.getNetworkInfo(network);
if((networkInfo.getState().equals(NetworkInfo.State.CONNECTED))){
return true;
}
}
return false;
}
}
package com.example.guangbo;
import androidx.appcompat.app.AppCompatActivity;
import android.content.IntentFilter;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity implements MyReceiver.NetWorkInfoInterface{
MyReceiver myReceiver;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
protected void onStart() {
super.onStart();
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
myReceiver = new MyReceiver();
registerReceiver(myReceiver,intentFilter);
myReceiver.getNetWorkInfo(this);
}
@Override
protected void onStop() {
super.onStop();
unregisterReceiver(myReceiver);
}
}
注：配置文件中需要添加权限和广播的配置信息
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<receiver
android:name=".MyReceiver"
android:enabled="true"
android:exported="true">
<intent-filter>
<action android:name="android.net.conn.CONNECTIVITY_CHANGE"></action>
<category android:name="android.intent.category.DEFAULT"></category>
</intent-filter>
</receiver>
4. 考完了，来总结一下
考了四个题：
- 图片浏览器ImageView
- 布局（想用什么用什么布局）
- activity跳转并且传递数据
- Fragment跳转传数据
都是做过的题目，但是第四个还是没做完，很多细节的知识也没有把握住，很一般了，跪求成绩不要太低。。。
- 安卓开发基础资料：
链接：https://pan.baidu.com/s/1WjjGhVldbwBNhfs7JxWRtQ
提取码：jtkq