Android数据持久化技术 — — —SharedPreferences

SharedPreferences是使用键值对的方式来存储数据。

要想使用SharedPreferences来存储数据，必须获取SharedPreferences对象，获取SharedPreferences对象的方法。

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Context.getSharedPreferences( )

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Activity.getPreferences( )

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PreferenceManager.getDefaultSharedPreferences( )

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方式：

1、获取SharedPreferences对象

2、通过SharedPreferences对象的edit( )方法获取SharedPreferences.Editor对象

3、向SharedPreferences.Editor对象中添加数据

4、使用commit( )方法提交数据

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package com.example.sharedprferencestest;

import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity implements View.OnClickListener{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button save_btn = (Button)findViewById(R.id.save_button);
        save_btn.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {

        SharedPreferences sharedPreferences = getSharedPreferences("data2",MODE_PRIVATE);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putString("用户名","wz");
        editor.putString("密码","root");
        editor.putBoolean("是否保存密码",false);
        editor.commit();
    }
}

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package com.example.sharedprferencestest;

import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity implements View.OnClickListener{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button save_btn = (Button)findViewById(R.id.save_button);
        save_btn.setOnClickListener(this);

        Button restore_btn =(Button)findViewById(R.id.restore_button);
        restore_btn.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {

        SharedPreferences sharedPreferences = getSharedPreferences("data2", MODE_PRIVATE);
        switch(v.getId()){
            case R.id.save_button:
                SharedPreferences.Editor editor = sharedPreferences.edit();
                editor.putString("用户名","wz");
                editor.putString("密码", "root");
                editor.putBoolean("是否保存密码", false);
                editor.commit();
                break;
            case R.id.restore_button:
                String username = sharedPreferences.getString("用户名",null);
                String password = sharedPreferences.getString("密码",null);
                boolean hint = sharedPreferences.getBoolean("是否改变密码", false);
                Toast.makeText(getApplicationContext(),username,Toast.LENGTH_SHORT).show();
                break;
            default:
                break;
        }

    }
}

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记住密码案例

package com.example.account;

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity implements View.OnClickListener{

    private Button btn;
    private EditText account;
    private EditText password;
    private CheckBox rememberPassword;

    private SharedPreferences sharedPreferences;
    private SharedPreferences.Editor editor;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        account = (EditText)findViewById(R.id.account);
        password = (EditText)findViewById(R.id.password);
        btn = (Button)findViewById(R.id.login);
        rememberPassword = (CheckBox)findViewById(R.id.remember_password);

        sharedPreferences = getSharedPreferences("login", MODE_PRIVATE);
        editor = sharedPreferences.edit();

        boolean isRemember = sharedPreferences.getBoolean("isRemember",false);

        if(isRemember){
            String username = sharedPreferences.getString("account","");
            String pwd = sharedPreferences.getString("password","");
            account.setText(username);
            password.setText(pwd);
            rememberPassword.setChecked(true);
        }

        btn.setOnClickListener(this);

    }

    @Override
    public void onClick(View v) {

        switch (v.getId()){
            case R.id.login:
                String accountContent = account.getText().toString();
                String passwordContent = password.getText().toString();
                if(accountContent.equals("root") && passwordContent.equals("root")){
                    if(rememberPassword.isChecked()){
                        editor.putString("account",accountContent);
                        editor.putString("password",passwordContent);
                        editor.putBoolean("isRemember",true);
                    }else{
                        editor.clear();
                    }
                    editor.commit();
                    Intent intent = new Intent();
                    intent.setClass(MainActivity.this,LoginSuccess.class);
                    startActivity(intent);
                    finish();
                }else{
                    Toast toast = Toast.makeText(MainActivity.this,"account or password is invalid",Toast.LENGTH_SHORT);
                    toast.show();
                }
                break;
            default:
                break;
        }
    }
}