用openFileOutput() 把文件放入SD卡

 AndroidManifest.xml

向AndroidManifest.xml中添加权限

<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

 

//写入文件
  button.setOnClickListener(new OnClickListener(){

   
   @SuppressLint("SdCardPath")
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    try {
     str=edittext.getText().toString();
     File saveFile = new File("/sdcard/a.txt");
     FileOutputStream outStream = new FileOutputStream(saveFile);
     outStream.write(str.getBytes());
     outStream.close();

     
    } catch (FileNotFoundException e) {
     // TODO Auto-generated catch block
     Toast.makeText(MainActivity.this,"111",Toast.LENGTH_LONG).show();
     e.printStackTrace();
    } catch (IOException e) {
     // TODO Auto-generated catch block
     Toast.makeText(MainActivity.this,"222",Toast.LENGTH_LONG).show();
     e.printStackTrace();
    }
   }
   
  });
  
  
  //读取文件
  button2.setOnClickListener(new OnClickListener(){

   @SuppressLint("SdCardPath")
   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    try {
     File saveFile = new File("/sdcard/a.txt");
     FileInputStream in = new FileInputStream(saveFile);
     byte[] str=new byte[1024];
     in.read(str);
     in.close();
     textview.setText(new String(str));
     
    } catch (FileNotFoundException e) {
     // TODO Auto-generated catch block
     Toast.makeText(MainActivity.this,"333",Toast.LENGTH_LONG).show();
     e.printStackTrace();
    } catch (IOException e) {
     // TODO Auto-generated catch block
     Toast.makeText(MainActivity.this,"444",Toast.LENGTH_LONG).show();
     e.printStackTrace();
    }
    
   }
   
  });