Android：利用SharedPreferences实现自动登录

public class LoginActivity extends Activity {
 private EditText username;
 private EditText userpassword;
 private CheckBox remember;
 private CheckBox autologin;
 private Button login;
 private SharedPreferences sp;
 private String userNameValue,passwordValue;

 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  // TODO Auto-generated method stub
  super.onCreate(savedInstanceState);
  setContentView(R.layout.login);

  
  // 初始化用户名、密码、记住密码、自动登录、登录按钮
  username = (EditText) findViewById(R.id.username);
  userpassword = (EditText) findViewById(R.id.userpassword);
  remember = (CheckBox) findViewById(R.id.remember);
  autologin = (CheckBox) findViewById(R.id.autologin);
  login = (Button) findViewById(R.id.login);

  sp = getSharedPreferences("userInfo", 0);
  String name=sp.getString("USER_NAME", "");
  String pass =sp.getString("PASSWORD", "");
  

  boolean choseRemember =sp.getBoolean("remember", false);
  boolean choseAutoLogin =sp.getBoolean("autologin", false);
 //  Toast.makeText(this, name, Toast.LENGTH_SHORT).show();
  
  //如果上次选了记住密码，那进入登录页面也自动勾选记住密码，并填上用户名和密码
  if(choseRemember){
   username.setText(name);
   userpassword.setText(pass);
   remember.setChecked(true);
  }
  //如果上次登录选了自动登录，那进入登录页面也自动勾选自动登录
  if(choseAutoLogin){
   autologin.setChecked(true);
  }
  
  
  
  login.setOnClickListener(new OnClickListener() {
  
   // 默认可登录帐号tinyphp,密码123
   @Override
   public void onClick(View arg0) {
    userNameValue = username.getText().toString();
    passwordValue = userpassword.getText().toString();
    SharedPreferences.Editor editor =sp.edit();
    
    // TODO Auto-generated method stub
    if (userNameValue.equals("tinyphp")
      && passwordValue.equals("123")) {
     Toast.makeText(LoginActivity.this, "登录成功",
       Toast.LENGTH_SHORT).show();
     
     //保存用户名和密码
     editor.putString("USER_NAME", userNameValue);
     editor.putString("PASSWORD", passwordValue);
     
     //是否记住密码
     if(remember.isChecked()){      
      editor.putBoolean("remember", true);      
     }else{
      editor.putBoolean("remember", false);    
     }
     
               
     //是否自动登录
      if(autologin.isChecked()){       
       editor.putBoolean("autologin", true);       
      }else{
       editor.putBoolean("autologin", false);
      }
     editor.commit();
      
     //跳转
     Intent intent =new Intent(LoginActivity.this,SuccessActivity.class);
     startActivity(intent);
    } else {
     Toast.makeText(LoginActivity.this, "用户名或密码错误，请重新登录!",
       Toast.LENGTH_SHORT).show();
    }

   }

  });

 }

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 android:padding="10dp" >

 <TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="用户名：" />

 <EditText
  android:id="@+id/username"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:ems="10"
  android:inputType="textPersonName" >
 </EditText>

 <TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_marginTop="10dp"
  android:text="密码：" />

 <EditText
  android:id="@+id/userpassword"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:ems="10"
  android:inputType="textPassword" >
 </EditText>

 <CheckBox
  android:id="@+id/remember"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="记住密码" />

 <CheckBox
  android:id="@+id/autologin"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="自动登录" />

 <Button
  android:id="@+id/login"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:text="登录" />

</LinearLayout>