基础学习总结（三）--文本、SD卡数据读写

简单的文本数据写入文件不需要权限，读写SD卡在4.0版本前需要写权限、在4.0后需要读写权限

布局：

<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="wrap_content"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <EditText android:id="@+id/et_number"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:phoneNumber="true"
        android:hint="请输入手机号" />

    <EditText
        android:id="@+id/et_pwd"
        android:layout_width="fill_parent"
        android:layout_height="match_parent"
        android:hint="请输入密码"
        android:inputType="textPassword" />
    
    <CheckBox android:id="@+id/cb_remerber_pwd"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checked="true"
        android:text="记住密码" />
    
    <Button android:id="@+id/btn_Login"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="登陆"
         />
    
</LinearLayout>

Manifest.xml添加权限

<!-- 写入外部设备(sdka)的权限 -->
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

MainActivity：

public class MainActivity extends Activity implements OnClickListener {
    private static final String TAG = "MainActivity";
    private EditText etNumber;
    private EditText etPwd;
    private CheckBox cbRemerber;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //获取控件中数据
        etNumber = (EditText)findViewById(R.id.et_number);
        etPwd=(EditText)findViewById(R.id.et_pwd);
        cbRemerber=(CheckBox)findViewById(R.id.cb_remerber_pwd);
        Button btnLogin = (Button)findViewById(R.id.btn_Login);
        //添加点击事件
        btnLogin.setOnClickListener(this);
        //获取SD卡数据
        Map<String,String> userInfo=UtilsOfSDCard.getUserInfo(this);
        if(userInfo!=null){
            etNumber.setText(userInfo.get("number"));
            etPwd.setText(userInfo.get("pwd")); 
        }
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        //1.取出账号，密码
        String Number=etNumber.getText().toString();
        String Pwd=etPwd.getText().toString();
        //判断是否有值，弹出吐司
        if(TextUtils.isEmpty(Number) || TextUtils.isEmpty(Pwd)){
            Toast.makeText(this, "请正确数据账号、密码", Toast.LENGTH_SHORT).show();
            return;
        }
        //2.判断cb是否被选中
        if(cbRemerber.isChecked()){
            Log.i(TAG, "记住密码"+Number+","+Pwd);
            boolean isSuccess=UtilsOfSDCard.saveUserInfo(this,Number, Pwd);
            if(isSuccess)
                Toast.makeText(this, "保存成功", Toast.LENGTH_SHORT).show();
            else
                Toast.makeText(this, "保存失败", Toast.LENGTH_SHORT).show();
        }
        
        //3.登陆成功
        Toast.makeText(this, "登陆成功", Toast.LENGTH_SHORT).show();
    }

    
}

UtilsOfSDCard类：

public class UtilsOfSDCard {
    //保存信息到sd卡
    public static boolean saveUserInfo(Context context, String number,String pwd){
        try {
            //获取SD卡状态
            String state=Environment.getExternalStorageState();
            //判断SD卡状态
            if(!Environment.MEDIA_MOUNTED.equals(state))
            {
                return false;
            }
            //动态获取SD卡路径
            File sdCardFile = Environment.getExternalStorageDirectory();
            File f=new File(sdCardFile,"qqLogin1.txt");
            //写入流
            FileOutputStream fos=new FileOutputStream(f);
            
            String data=number+"##"+pwd;
            fos.write(data.getBytes());
            fos.flush();
            fos.close();
            return true;
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        return false;
    }
    
    //返回信息
    public static Map<String,String> getUserInfo(Context context){
        try {
            String state=Environment.getExternalStorageState();
            if(!Environment.MEDIA_MOUNTED.equals(state))
            {
                return null;
            }
            File sdCartFile=Environment.getExternalStorageDirectory();
            File f=new File(sdCartFile,"qqLogin1.txt");
            BufferedReader br=new BufferedReader(new InputStreamReader(new FileInputStream(f)));
            String text=br.readLine();
            br.close();
            if(!TextUtils.isEmpty(text)){
                Map<String,String> userInfoMap=new HashMap<String,String>();
                String[] split = text.split("##");
                userInfoMap.put("number", split[0]);
                userInfoMap.put("pwd", split[1]);
                Log.w("UtilsOfSDCard", split[0]+","+split[1]);
                return userInfoMap;
            }
            
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        return null;
    }
}

Utils类：

public class Utils {
    /*
     * 保存用户信息
     * */
    public static boolean saveUserInfo(String number,String pwd){
        
        try {
            String path="/data/data/com.cui.qqlogin/QQLogin.txt";
            //写入流
            FileOutputStream fs=new FileOutputStream(path);
            String data=number+"##"+pwd;
            fs.write(data.getBytes());
            fs.flush();
            fs.close();
            return true;
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        return false;
    }
    
public static boolean saveUserInfo(Context context, String number,String pwd){
        
        try {
            //动态获取文件路径
            File filesDir = context.getFilesDir();
            File f=new File(filesDir,"QQLogin.txt");
            //写入流
            FileOutputStream fs=new FileOutputStream(f);
            String data=number+"##"+pwd;
            fs.write(data.getBytes());
            fs.flush();
            fs.close();
            return true;
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        return false;
    }
    
    public static Map<String,String> getUserInfo(){
        try {
            String path="/data/data/com.cui.qqlogin/QQLogin.txt";
            //输出流
            FileInputStream fis=new FileInputStream(path);
            //字符流
            BufferedReader reader=new BufferedReader(new InputStreamReader(fis));
            String text = reader.readLine();
            if(!TextUtils.isEmpty(text)){
                String[] split=text.split("##");
                Map<String,String> userofMap=new HashMap<String,String>();
                userofMap.put("number", split[0]);
                userofMap.put("pwd", split[1]);
                return userofMap;
            }
            
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        return null;
    }
    
    public static Map<String,String> getUserInfo(Context context){
        try {
            //String path="/data/data/com.cui.qqlogin/QQLogin.txt";
            //动态获取文件路径
            File filesDir = context.getFilesDir();
            File f=new File(filesDir,"QQLogin.txt");
            //输出流
            FileInputStream fis=new FileInputStream(f);
            //字符流
            BufferedReader reader=new BufferedReader(new InputStreamReader(fis));
            String text = reader.readLine();
            reader.close();
            if(!TextUtils.isEmpty(text)){
                String[] split=text.split("##");
                Map<String,String> userofMap=new HashMap<String,String>();
                userofMap.put("number", split[0]);
                userofMap.put("pwd", split[1]);
                return userofMap;
            }
            
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        return null;
    }
}

====================插播快捷键

Ctrl+N 快速新建
Ctrl+H 选中项目中搜索
Ctrl+L 跳转到指定行
Ctrl+F 在文本中查找内容

====================

文件存储地址:

this.getFilesDir(); // /data/data/包名/files
this.getCacheDir(); // /data/data/包名/cache
openFileOutput("aa.txt", 0); /data/data/包名/files/aa.txt
context.getSharedPreferences("cuidemo", context.MODE_PRIVATE); /data/data/包名/shared_prefs/cuidemo.xml

public class UtilsOfSharedPreferences {
    //保存信息到sd卡
    public static boolean saveUserInfo(Context context, String number,String pwd){
        try {
    sp=context.getSharedPreferences("cuidemo", context.MODE_PRIVATE);
            //获得一个编辑对象
            Editor edit = sp.edit();
            edit.putString("number", number);
            edit.putString("pwd", pwd);
            edit.commit();
            return true;
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return false;
    }
    
    //返回信息
    public static Map<String,String> getUserInfo(Context context){
        SharedPreferences sp=context.getSharedPreferences("cuidemo", context.MODE_PRIVATE);
        String number=sp.getString("number", null);
        String pwd=sp.getString("pwd", null);
        
        if(!TextUtils.isEmpty(number)&& !TextUtils.isEmpty(pwd)){
            Map<String,String> userInfoMap=new HashMap<String,String>();
            userInfoMap.put("number", number);
            userInfoMap.put("pwd", pwd);
            return userInfoMap;
        }
        
        return null;
    }
}

权限相关:
1. 私有文件
Context.MODE_PRIVATE
2. 可读文件
Context.MODE_WORLD_READABLE
3. 可写文件
Context.MODE_WORLD_WRITEABLE
4. 可读可写文件.
Context.MODE_WORLD_WRITEABLE+Context.MODE_WORLD_READABLE

权限二进制图解：