SharedPrefernces使用实例讲解

activity_main.xml

   

    

     <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" >
    

    

      
    

    

         <EditText
    

    

             android:id="@+id/userName"
    

    

             android:layout_width="wrap_content"
    

    

             android:layout_height="wrap_content"
    

    

             android:hint="Please input your username" />
    

    

      
    

    

         <EditText
    

    

             android:id="@+id/passWord"
    

    

             android:layout_width="wrap_content"
    

    

             android:layout_height="wrap_content"
    

    

             android:hint="Please input your password"
    

    

             android:inputType="textPassword" />
    

    

      
    

    

         <Button
    

    

             android:id="@+id/btn_login"
    

    

             android:layout_width="wrap_content"
    

    

             android:layout_height="wrap_content"
    

    

             android:text="login"
    

    

             android:textSize="30sp" />
    

    

      
    

    

     </LinearLayout>
    

   

activity_second.xml

   

    

     <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" >
    

    

      
    

    

         <TextView
    

    

             android:id="@+id/info"
    

    

             android:layout_width="wrap_content"
    

    

             android:layout_height="wrap_content" />
    

    

      
    

    

         <Button
    

    

             android:id="@+id/btn_showinfo"
    

    

             android:layout_width="wrap_content"
    

    

             android:layout_height="wrap_content"
    

    

             android:text="showIfo" />
    

    

      
    

    

     </LinearLayout>
    

   

MainActivity.java

   

    

     package com.example.testsharedpreferencesdemo001;
    

    

      
    

    

     import android.annotation.SuppressLint;
    

    

     import android.app.Activity;
    

    

     import android.content.Intent;
    

    

     import android.content.SharedPreferences;
    

    

     import android.content.SharedPreferences.Editor;
    

    

     import android.os.Bundle;
    

    

     import android.view.View;
    

    

     import android.view.View.OnClickListener;
    

    

     import android.widget.Button;
    

    

     import android.widget.EditText;
    

    

      
    

    

     public class MainActivity extends Activity
    

    

     {
    

    

      
    

    

     	SharedPreferences sharedPreferences;
    

    

     	Editor editor;
    

    

     	EditText userName, passWord;
    

    

     	Button login;
    

    

      
    

    

     	@SuppressLint("CommitPrefEdits")
    

    

     	@Override
    

    

     	protected void onCreate(Bundle savedInstanceState)
    

    

     	{
    

    

     		super.onCreate(savedInstanceState);
    

    

     		setContentView(R.layout.activity_main);
    

    

     		userName = (EditText) findViewById(R.id.userName);
    

    

     		passWord = (EditText) findViewById(R.id.passWord);
    

    

      
    

    

     		login = (Button) findViewById(R.id.btn_login);
    

    

     		login.setOnClickListener(myOnClickListener);
    

    

      
    

    

     		sharedPreferences = this.getSharedPreferences("login_info",
    

    

     				MODE_PRIVATE);
    

    

      
    

    

     		String stored_username = sharedPreferences.getString("username", "");
    

    

     		String stored_password = sharedPreferences.getString("password", "");
    

    

     		userName.setText(stored_username);
    

    

     		passWord.setText(stored_password);
    

    

     		editor = sharedPreferences.edit();
    

    

     		editor.putString("username", userName.getText().toString());
    

    

     		editor.putString("password", passWord.getText().toString());
    

    

      
    

    

     	}
    

    

      
    

    

     	OnClickListener myOnClickListener = new OnClickListener()
    

    

     	{
    

    

      
    

    

     		@Override
    

    

     		public void onClick(View v)
    

    

     		{
    

    

     			String sUserName = userName.getText().toString();
    

    

     			String sPassWord = passWord.getText().toString();
    

    

      
    

    

     			Intent intent = new Intent(MainActivity.this, SecondActivity.class);
    

    

     			intent.putExtra("username", sUserName);
    

    

     			intent.putExtra("password", sPassWord);
    

    

      
    

    

     			startActivity(intent);
    

    

      
    

    

     		}
    

    

     	};
    

    

     }
    

   

SecondActivity.java

   

    

     package com.example.testsharedpreferencesdemo001;
    

    

      
    

    

     import android.app.Activity;
    

    

     import android.content.Intent;
    

    

     import android.os.Bundle;
    

    

     import android.view.View;
    

    

     import android.view.View.OnClickListener;
    

    

     import android.widget.Button;
    

    

     import android.widget.TextView;
    

    

     import android.widget.Toast;
    

    

      
    

    

     public class SecondActivity extends Activity
    

    

     {
    

    

     	String userName;
    

    

     	String passWord;
    

    

     	TextView info;
    

    

     	Button btn_showInfo;
    

    

      
    

    

     	@Override
    

    

     	protected void onCreate(Bundle savedInstanceState)
    

    

     	{
    

    

      
    

    

     		super.onCreate(savedInstanceState);
    

    

     		this.setContentView(R.layout.activity_second);
    

    

      
    

    

     		info = (TextView) findViewById(R.id.info);
    

    

     		btn_showInfo = (Button) findViewById(R.id.btn_showinfo);
    

    

     		btn_showInfo.setOnClickListener(new OnClickListener()
    

    

     		{
    

    

      
    

    

     			@Override
    

    

     			public void onClick(View v)
    

    

     			{
    

    

     				Toast.makeText(SecondActivity.this, userName + ";" + passWord,
    

    

     						Toast.LENGTH_LONG).show();
    

    

     			}
    

    

     		});
    

    

     		Intent intent = this.getIntent();
    

    

     		userName = intent.getStringExtra("username");
    

    

     		passWord = intent.getStringExtra("password");
    

    

     		System.out.println(userName);
    

    

     		System.out.println(passWord);
    

    

      
    

    

     	}
    

    

      
    

    

     }
    

   

MainActivity

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点击按钮，跳转到SecondActivty，再次点击按钮showinfo

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点击“返回键”

回到MainAcitivy

可以看到用户名与密码均保留着

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