吴裕雄--天生自然ANDROID开发学习:4.1.2 Activity初窥门径

package example.jay.com.activitytest1;

import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.RadioGroup;


public class MyActivity extends ActionBarActivity {

    private Button btnregister;
    private EditText editname;
    private RadioGroup rad;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);

        btnregister = (Button)findViewById(R.id.btnregister);
        editname = (EditText)findViewById(R.id.editname);
        rad = (RadioGroup)findViewById(R.id.radioGroup);
        btnregister.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name,sex = "";
                Intent it = new Intent(MyActivity.this,MyActivity2.class);

                name = editname.getText().toString();

                //遍历RadioGroup找出被选中的单选按钮
                for(int i = 0;i < rad.getChildCount();i++)
                {
                    RadioButton rd = (RadioButton)rad.getChildAt(i);
                    if(rd.isChecked())
                    {
                        sex = rd.getText().toString();
                        break;
                    }
                }

                //新建Bundle对象,并把数据写入
                Bundle bd = new Bundle();
                bd.putCharSequence("user",name);
                bd.putCharSequence("sex",sex);

                //将数据包Bundle绑定到Intent上
                it.putExtras(bd);
                startActivity(it);
                //关闭第一个Activity
                finish();

            }
        });
    }
}
package example.jay.com.activitytest1;

import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.widget.TextView;


public class MyActivity2 extends ActionBarActivity {

    private TextView txtshow;
    private String name;
    private String sex;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my_activity2);

        txtshow = (TextView)findViewById(R.id.txtshow);
        //获得Intent对象,并且用Bundle出去里面的数据
        Intent it = getIntent();
        Bundle bd = it.getExtras();

        //按键值的方式取出Bundle中的数据
        name = bd.getCharSequence("user").toString();
        sex = bd.getCharSequence("sex").toString();
        txtshow.setText("尊敬的"+name + " " + sex + "士"+"恭喜你,注册成功~");
    }

}
2.多个Activity间的交互(后一个传回给前一个)

3.知晓当前是哪个Activity

4.随时关闭所有Activity

具体代码如下:

public class ActivityCollector {  
    public static LinkedList<Activity> activities = new LinkedList<Activity>();  
    public static void addActivity(Activity activity)  
    {  
        activities.add(activity);  
    }  
    public static void removeActivity(Activity activity)  
    {  
        activities.remove(activity);  
    }  
    public static void finishAll()  
    {  
        for(Activity activity:activities)  
        {  
            if(!activity.isFinishing())  
            {  
                activity.finish();  
            }  
        }  
    }  
}  
5.完全退出App的方法
上面说的是关闭所有Activity的,但是有些时候我们可能想杀死整个App,连后台任务都杀死 杀得一干二净的话,可以使用搭配着下述代码使用:
实现代码:

/** 
 * 退出应用程序 
 */  
public void AppExit(Context context) {  
    try {  
        ActivityCollector.finishAll();  
        ActivityManager activityMgr = (ActivityManager) context  
                .getSystemService(Context.ACTIVITY_SERVICE);  
        activityMgr.killBackgroundProcesses(context.getPackageName());  
        System.exit(0);  
    } catch (Exception ignored) {}  
}  
6.双击退出程序的两种方法:
1)定义一个变量,来标识是否退出
// 定义一个变量,来标识是否退出
private static boolean isExit = false;
Handler mHandler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        super.handleMessage(msg);
        isExit = false;
    }
};

public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        if (!isExit) {
            isExit = true;
            Toast.makeText(getApplicationContext(), "再按一次退出程序",
                    Toast.LENGTH_SHORT).show();
            // 利用handler延迟发送更改状态信息
            mHandler.sendEmptyMessageDelayed(0, 2000);
        } else {
            exit(this);
        }
        return false;
    }
return super.onKeyDown(keyCode, event);}
2)保存点击时间:
//保存点击的时间
private long exitTime = 0;
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        if ((System.currentTimeMillis() - exitTime) > 2000) {
            Toast.makeText(getApplicationContext(), "再按一次退出程序",
                    Toast.LENGTH_SHORT).show();
            exitTime = System.currentTimeMillis();
        } else {
                        exit();
                      }
        return false;
    }
        return super.onKeyDown(keyCode, event);
}

2)方法二:
通过style进行配置,这个是全局的哦,就是所有的Activity都会加载这个动画!

实现代码如下:

①在style.xml中自定义style:

<!-- 默认Activity跳转动画 -->
<style name="default_animation" mce_bogus="1" parent="@android:style/Animation.Activity">
    <item name="android:activityOpenEnterAnimation">@anim/default_anim_in</item>
    <item name="android:activityOpenExitAnimation">@anim/anim_stay</item>
    <item name="android:activityCloseEnterAnimation">@anim/anim_stay</item>
    <item name="android:activityCloseExitAnimation">@anim/default_anim_out</item>
</style>
解释:

4个item分别代表:

Activity A跳转到Activity B时Activity B进入动画;
Activity A跳转到Activity B时Activity A退出动画;
Activity B返回Activity A时Activity A的进入动画
Activity B返回Activity A时ActivityB的退出动画
②然后修改下AppTheme:

<style name="AppTheme" mce_bogus="1" parent="@android:style/Theme.Light">
        <item name="android:windowAnimationStyle">@style/default_animation</item>
        <item name="android:windowNoTitle">true</item>
</style>
③最后在appliction设置下:

<application
   android:icon="@drawable/logo"
   android:label="@string/app_name"
   android:theme="@style/AppTheme" >
10.设置Activity全屏的方法:
1)代码隐藏ActionBar
在Activity的onCreate方法中调用getActionBar.hide();即可

2)通过requestWindowFeature设置
requestWindowFeature(Window.FEATURE_NO_TITLE); 该代码需要在setContentView ()之前调用,不然会报错
3)通过AndroidManifest.xml的theme
在需要全屏的Activity的标签内设置 theme = @android:style/Theme.NoTitleBar.FullScreen

11.onWindowFocusChanged方法妙用:
我们先来看下官方对这个方法的介绍:

12.定义对话框风格的Activity
直接设置下Activity的theme:

android:theme="@android:style/Theme.Dialog"这样就可以了,当然你可以再设置下标题,小图标!
//设置左上角小图标
requestWindowFeature(Window.FEATURE_LEFT_ICON);
setContentView(R.layout.main);
getWindow().setFeatureDrawableResource(Window.FEATURE_LEFT_ICON, android.R.drawable.ic_lion_icon);
//设置文字:
setTitle(R.string.actdialog_title);  //XML代码中设置:android:label="@string/activity_dialog"

  

原文地址:https://www.cnblogs.com/tszr/p/13583115.html