Android的SharedPreferences实用技巧

转自：http://blog.csdn.net/jingfeizhu/article/details/10017779

SharedPreferences也是一种轻型的数据存储方式，它的本质是基于XML文件存储key-value键值对数据，通常用来存储一些简单的配置信息。其存储位置在/data/data/<包名>/shared_prefs目录下。SharedPreferences对象本身只能获取数据而不支持存储和修改，存储修改是通过Editor对象实现。实现SharedPreferences存储的步骤如下：
一、根据Context获取SharedPreferences对象
二、利用edit()方法获取Editor对象。
三、通过Editor对象存储key-value键值对数据。
四、通过commit()方法提交数据。

public class MainActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);
       
       //获取SharedPreferences对象
       Context ctx = MainActivity.this;       
       SharedPreferences sp = ctx.getSharedPreferences("pref", MODE_PRIVATE);
       //存入数据
       Editor editor = sp.edit();
       editor.putString("name", "jeff");
       editor.putInt("score", 0);
       editor.putBoolean("playagain", true);
       editor.commit();
       
    }
}

上面的例子使用起来比较麻烦，这里给出一种简单的封装方案：

import java.util.Map.Entry;


import android.content.ContentValues;
import android.content.Context;
import android.content.SharedPreferences;


public class MyPreference {

    private static final String PREFERENCE_NAME = "my.db";

    private SharedPreferences mPreference;

    public MyPreference(Context ctx) {
        mPreference = ctx.getApplicationContext().getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
    }


    public boolean putStringAndCommit(String key, String value) {
        return mPreference.edit().putString(key, value).commit();
    }


    public boolean putIntAndCommit(String key, int value) {
        return mPreference.edit().putInt(key, value).commit();
    }

    public boolean putBooleanAndCommit(String key, boolean value) {
        return mPreference.edit().putBoolean(key, value).commit();
    }

    public boolean putIntAndCommit(ContentValues values) {
        SharedPreferences.Editor editor = mPreference.edit();
        for (Entry<String, Object> value : values.valueSet()) {
            editor.putString(value.getKey(), value.getValue().toString());
        }
        return editor.commit();
    }


    public String getString(String key) {
        return getString(key, "");
    }

    public String getString(String key, String defValue) {
        return mPreference.getString(key, defValue);
    }

    public int getInt(String key) {
        return getInt(key, -1);
    }


    public int getInt(String key, int defValue) {
        return mPreference.getInt(key, defValue);
    }

    public boolean getBoolean(String key) {
        return getBoolean(key, false);
    }

    public boolean getBoolean(String key, boolean defValue) {
        return mPreference.getBoolean(key, defValue);
    }
}

使用方式如下：

public class MainActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);
       
       MyPreference pref = new MyPreference(this);
       pref.putStringAndCommit("name", "jeff");
       
    }
}