Android SharedPreference的使用

在《Android 在内部存储读写文件》一文中，谈到了登录用户名和密码的方法，通过读取内存文件来实现，但是会出现问题，因为登录名和密码的形式通过username##password的形式，读取的时候以##为分割线，但是一旦用户名中存在##就会出现问题，本文使用SharedPreference来解决这个问题

1. 定义布局
使用之前的布局
2. 把组件的状态用SharedPreference保存起来

* 往SharedPreference里写数据

//拿到一个SharedPreference对象
SharedPreferences sp = getSharedPreferences("config", MODE_PRIVATE);
//拿到编辑器
Editor ed = sp.edit();
ed.putBoolean("checkBox", isChecked);
ed.commit();

* 从SharedPreference里取数据

SharedPreferences sp = getSharedPreferences("config", MODE_PRIVATE);
//从SharedPreference里取数据
boolean b = sp.getBoolean("checkBox", false);

简化后的代码如下：

package com.wuyudong.sharedpreference;

import android.os.Bundle;
import android.app.Activity;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // 获取到SharedPreference对象
        SharedPreferences sp = getSharedPreferences("info", MODE_PRIVATE);
        //获取sp中的内容
        String name = sp.getString("name", "");
        String pass = sp.getString("pass", "");
        EditText et_name = (EditText) findViewById(R.id.et_name);
        EditText et_pass = (EditText) findViewById(R.id.et_pass);
        //数据回显至输入框
        et_name.setText(name);
        et_pass.setText(pass);
    }

    public void click(View v) {
        EditText et_name = (EditText) findViewById(R.id.et_name);
        EditText et_pass = (EditText) findViewById(R.id.et_pass);

        String name = et_name.getText().toString();
        String pass = et_pass.getText().toString();

        // 获取到SharedPreference对象
        SharedPreferences sp = getSharedPreferences("info", MODE_PRIVATE);
        // 得到编辑器
        Editor ed = sp.edit();
        ed.putString("name", name);
        ed.putString("pass", pass);
        ed.commit();
    }

}

其实android中的很多设置都用到了SharedPreference

例如

查看com.android.settings/shared_prefs下的com.android.settings_preferences.xml文件

<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map>
    <boolean name="sound_effects" value="true" />
    <boolean name="com.android.inputmethod.latin/.LatinIME" value="true" />
    <boolean name="force_hw_ui" value="false" />
    <boolean name="jp.co.omronsoft.openwnn/.OpenWnnJAJP" value="false" />
    <boolean name="auto_time" value="false" />
    <boolean name="show_hw_screen_udpates" value="false" />
    <boolean name="24 hour" value="true" />
    <boolean name="dock_sounds" value="false" />
    <string name="font_size">1.30</string>
    <boolean name="allow_mock_location" value="false" />
    <boolean name="keep_screen_on" value="false" />
    <boolean name="show_hw_layers_udpates" value="false" />
    <string name="date_format"></string>
    <boolean name="enable_adb" value="false" />
    <boolean name="enforce_read_external" value="false" />
    <boolean name="show_touches" value="false" />
    <boolean name="dtmf_tone" value="true" />
    <boolean name="strict_mode" value="false" />
    <boolean name="com.example.android.softkeyboard/.SoftKeyboard" value="false" />
    <boolean name="show_hw_overdraw" value="false" />
    <boolean name="auto_zone" value="false" />
    <string name="hdcp_checking">drm-only</string>
    <boolean name="show_cpu_usage" value="false" />
    <boolean name="debug_layout" value="false" />
    <boolean name="com.android.inputmethod.pinyin/.PinyinIME" value="false" />
    <boolean name="pointer_location" value="false" />
    <boolean name="disable_overlays" value="false" />
    <boolean name="bugreport_in_power" value="false" />
    <boolean name="haptic_feedback" value="true" />
    <boolean name="immediately_destroy_activities" value="false" />
    <boolean name="show_all_anrs" value="false" />
    <boolean name="verify_apps_over_usb" value="false" />
    <boolean name="lock_sounds" value="true" />
    <boolean name="show_screen_updates" value="false" />
    <boolean name="force_msaa" value="false" />
    <boolean name="wait_for_debugger" value="false" />
</map>