Android通过SharedPreferences实现自动登录记住用户名和密码功能

package com.dt5000.ischool.activity; 
import android.annotation.SuppressLint; 
import android.content.Context; 
import android.content.Intent; 
import android.content.SharedPreferences; 
import android.content.SharedPreferences.Editor; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.KeyEvent; 
import android.view.View; 
import android.widget.CheckBox; 
import android.widget.EditText; 
import com.dt5000.ischool.util.DTUtil; 
import com.dt5000.ischool.util.MyApplication; 
/** 
 * @author： duanyr 
 * @创建时间： 2012-11-13 下午2:36:47 
 * 
 * @类说明：登录界面 
 */ 
@SuppressLint("WorldReadableFiles") 
public class LoginActivity extends DTUtil { 
  private static final String TAG = "用户登录"; 
  private EditText username; 
  private EditText password; 
  private CheckBox autoLogin; 
  private SharedPreferences sharedPreferences; 
  private String message; 
  @Override 
  public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    MyApplication.getInstance().addActivity(this); 
    sharedPreferences = this.getSharedPreferences("userInfo",Context.MODE_WORLD_READABLE); 
    if (sharedPreferences.getBoolean("AUTO_ISCHECK", false)) { 
      Intent intent = new Intent(); 
      intent.setClass(LoginActivity.this, MainActivity.class); 
      startActivity(intent); 
    } else { 
      setContentView(R.layout.activity_login); 
      initView(); 
    } 
  } 
  /** 
   * 初始化视图控件 
   */ 
  public void initView() { 
    Log.i(TAG, "初始化视图控件"); 
    username = (EditText) findViewById(R.id.username); 
    password = (EditText) findViewById(R.id.password); 
    autoLogin = (CheckBox) findViewById(R.id.autoLogin); 
    // 默认记住用户名 
    username.setText(sharedPreferences.getString("userName", "")); 
  } 
  /** 
   * 点击登录按钮时触发的方法 
   * @param view 
   */ 
  public void userLogin(View view) { 
    String usernameString = username.getText().toString(); 
    String passwordString = password.getText().toString(); 
    if (validateUser(usernameString, passwordString)) { 
      Editor editor = sharedPreferences.edit(); 
      editor.putString("userName", usernameString); 
      if (autoLogin.isChecked()) {// 自动登录 
        editor.putString("password", passwordString); 
        editor.putBoolean("AUTO_ISCHECK", true).commit(); 
      } 
      editor.commit(); 
      Intent intent = new Intent(); 
      intent.setClass(LoginActivity.this, MainActivity.class); 
      startActivity(intent); 
    } else { 
      alert(this, message); 
    } 
  } 
  //游客登录 
  public void visitorLogin(View view) { 
    Intent intent = new Intent(); 
    intent.setClass(LoginActivity.this, MainActivity.class); 
    startActivity(intent); 
  } 
  /** 
   * 验证用户名密码是否正确 
   * 
   * @param username 
   * @param password 
   * @return 
   */ 
  public boolean validateUser(String username, String password) { 
    Boolean flag = false; 
    try { 
      //...此处为调用web服务，验证用户名密码的服务，特此省略 
      flag = true; 
    } catch (Exception e) { 
      // TODO Auto-generated catch block 
      Log.e(TAG, e.getMessage()); 
      message = "连接服务器失败"; 
    } 
    return flag; 
  } 
  /** 
   * 点击退出按钮时触发的方法 
   */ 
  public void logout_listener(View view) { 
    dialog_Exit(this); 
  } 
  /** 
   * 监听返回按钮，此为登录界面再返回的话给出退出提示 
   */ 
  public boolean onKeyDown(int keyCode, KeyEvent event) { 
    if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) { 
      dialog_Exit(this); 
      return false; 
    } 
    return false; 
  } 
} 

<?xml version='1.0' encoding='utf-8' standalone='yes' ?> 
<map> 
<string name="userName">777</string> 
<string name="password">111111</string> 
<boolean name="AUTO_ISCHECK" value="true" /> 
</map>