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

点击按钮，跳转到SecondActivty，再次点击按钮showinfo

点击“返回键”

回到MainAcitivy

可以看到用户名与密码均保留着