//申明SharedPreferences对象

SharedPreferences mSharedPreferences; SharedPreferences.Editor mEditor;

mSharedPreferences = getSharedPreferences("user", Context.MODE_PRIVATE); mEditor = mSharedPreferences.edit();

//在主方法里写一个点击事件保存数据

Button left = (Button) findViewById(R.id.left);

left.setOnClickListener(new View.OnClickListener() {
      @Override     public void onClick(View v) {
          WriteToSd();         mEditor.putString("user",editText1.getText().toString());         mEditor.putString("passWorld",editText2.getText().toString());         mEditor.commit();     } }); user = mSharedPreferences.getString("user",null); passWorld = mSharedPreferences.getString("passWorld",null); editText1.setText(user); editText2.setText(passWorld);

//读取文件 private void ReadFromSd(){
      String s = Environment.getExternalStorageState();     File root = Environment.getExternalStorageDirectory();     File TargetDir = new File(root,super.getPackageName());     ObjectInputStream ois = null;     if (TargetDir.exists()){
          try {
              ois = new ObjectInputStream(new FileInputStream(new File(TargetDir+"/liu.txt")));             People people = (People) ois.readObject();             Toast.makeText(getApplication(),people.getUser().toString()+people.getPwd().toString(),Toast.LENGTH_SHORT).show();         } catch (IOException e) {
              e.printStackTrace();         } catch (ClassNotFoundException e) {
              e.printStackTrace();         }finally {
              try {
                  ois.close();             } catch (IOException e) {
                  e.printStackTrace();             }         }     }else {
          Toast.makeText(getApplication(),"false",Toast.LENGTH_SHORT).show();     } } 写入文件 private void WriteToSd(){
      String s = Environment.getExternalStorageState();     ObjectOutputStream oos = null;     if (s.equals(Environment.MEDIA_MOUNTED)){//判断是否有权限,记得在清单文件里声明权限,6.1版本之后的手机可能还是不行         File root = Environment.getExternalStorageDirectory();         File tag = new File(root ,super.getPackageName());         if (!tag.exists()){  //判断文件是否存在

tag.mkdir();         }         try {
              oos = new ObjectOutputStream(new FileOutputStream(new File(tag,"liu,txt")));             People people = new People("liu","yifan");             oos.writeObject(people);         } catch (IOException e) {
              e.printStackTrace();         }     }

    
     //写在这里面 //两个权限