android下的读写权限-CFANZ编程社区

建立两个项目，一个是写数据_相关,一个是读数据_相关数据，

写数据_相关

读数据_相关数据作用:对上面的项目的文件进行读写操作，看看是否能成功

android下的读写权限_android

写数据_相关:

package com.sqf.writedata;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends Activity {

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    
    //写数据
    
    //私有文件
    writeToLocal("private.txt",Context.MODE_PRIVATE);
    
    //可读文件
    writeToLocal("readable.txt", Context.MODE_WORLD_READABLE);
    
    //可写文件
    writeToLocal("writeable.txt", Context.MODE_WORLD_WRITEABLE);
    
    //可读可写文件.
    writeToLocal("readable_writeable.txt", Context.MODE_WORLD_READABLE+Context.MODE_WORLD_WRITEABLE);
    
    
  }
  
  private void writeToLocal(String fileName,int mode){
     
    try {
        //  /data/data/包名/files/ 
          //第一个参数是data/data/包名/files/下的文件名,di二是参数是权限
      FileOutputStream fos = openFileOutput(fileName, mode);
      fos.write(("第一个程序写的数据"+fileName).getBytes());
      fos.flush();
      fos.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
    
  }
 
}

读数据_相关数据:

package com.sqf.write;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.util.concurrent.locks.ReentrantReadWriteLock.ReadLock;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {

  //为什么不能动态获取？   因为这是另一个项目的地址
  private String basicPath = "/data/data/com.sqf.writedata/files/";
  
  
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    
    
    
    findViewById(R.id.btn_read_private).setOnClickListener(this);
    findViewById(R.id.btn_write_private).setOnClickListener(this);
    
    findViewById(R.id.btn_read_readable).setOnClickListener(this);
    findViewById(R.id.btn_write_readable).setOnClickListener(this);
    
    findViewById(R.id.btn_read_writeable).setOnClickListener(this);
    findViewById(R.id.btn_write_writeable).setOnClickListener(this);
    
    findViewById(R.id.btn_read_readable_writeable).setOnClickListener(this);
    findViewById(R.id.btn_write_readable_writeable).setOnClickListener(this);
    
  }

  /**
   * 哪一个空间被点击,V对象就代表被点击的对象
   * */
  @Override
  public void onClick(View v) {
  
    switch(v.getId()){
        
      case R.id.btn_read_private:
        readFile("private.txt");
        break;
      case R.id.btn_write_private:
        writeFile("private.txt");
        break;
        
      case R.id.btn_read_readable:
        readFile("readable.txt");
        break;
      case R.id.btn_write_readable:
        writeFile("readable.txt");
        break;
        
      case R.id.btn_read_writeable:
        readFile("writeable.txt");
        break;
      case R.id.btn_write_writeable:
        writeFile("writeable.txt");
        break;
        
      case R.id.btn_read_readable_writeable:
        readFile("readable_writeable.txt");
        break;
      case R.id.btn_write_readable_writeable:
        writeFile("readable_writeable.txt");
        break;
    
    }
    
  }
  
  private void readFile(String fileName){
    
    try {
      String path = basicPath + fileName;
      BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(path)));
      String text = reader.readLine();
      reader.close();
      
      Toast.makeText(this, "读取成功", 0).show();
    } catch (Exception e) {
      Toast.makeText(this, "读取失败"+fileName, 0).show();
      e.printStackTrace();
    }
  }
  
  
  private void writeFile(String fileName){
    
    try {
      String path = basicPath + fileName;
      
      FileOutputStream fos = new FileOutputStream(path);
      fos.write("哈哈，被别人黑了".getBytes());
      fos.flush();
      fos.close();
      
      Toast.makeText(this, "写入成功"+fileName, 0).show();
    } catch (Exception e) {
      e.printStackTrace();
      Toast.makeText(this, "写入失败", 0).show();
    }
  }

 
}

<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" 
    android:orientation="vertical" >
    
    <Button 
        android:id="@+id/btn_read_private"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="读私有数据"
        />
    <Button 
         android:id="@+id/btn_write_private"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="写私有数据"
     />
    
    <Button 
         android:id="@+id/btn_read_readable"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="读可读数据"
        />
    <Button 
        android:id="@+id/btn_write_readable"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="写可读数据"
     />
    
    <Button
         android:id="@+id/btn_read_writeable"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="读可写数据"
        />
    <Button
       android:id="@+id/btn_write_writeable"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="写可写数据"
     />
    
      <Button 
        android:id="@+id/btn_read_readable_writeable"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="读可读可写数据"
        />
    <Button 
        android:id="@+id/btn_write_readable_writeable"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="写可读可写数据"
     />
      
      
</LinearLayout>