Android 不同应用通过SharedPreference实现共享数据

Android不同应用之间数据的共享有许多方式，但是我觉得还是使用sharedPreference比较简单和轻量级。如果程序B想要访问程序A的sharedPreference可以通过下面的语句来实现：

try {
    AContext =createPackageContext(A_PACKAGE_NAME,
            Context.CONTEXT_IGNORE_SECURITY);
} catch (NameNotFoundException e) {
    Log.e(TAG, "find package error!");
}
SharedPreferences sp = AContext.getSharedPreferences(PREFERENCES_NAME,
        Context.MODE_WORLD_READABLE);
sp.getInt(PREF_NAME, 0);

当然在A程序里创建SharedPreference的时候也需要使用Context.MODE_WORLD_READABLE属性。另外 SharedPreference还有Context.MODE_WORLD_WRITEABLE属性。根据SDK的解释，就是允许别的应用程序来对 SharedPreference进行写操作。但是在实际程序实验中发现即使加上了这个属性，写操作也是无法成功的，会提示一个错误：Couldn't rename file /data/data/....PREFERENCES_NAME.XML to  /data/data/....PREFERENCES_NAME.XML.bak。这个错误的原因应该是很明确了，程序B在程序A的目录里面没有创建 和重命名文件的权限。

 

     那么到底要怎么样才能让程序B在程序A的SharedPreferences里面写东西呢，其实很简单，在manifest.xml里面将两个应用程序 的android:sharedUserId属性设为相同的就可以了。而且SharedPreference的属性也不需要 Context.MODE_WORLD_WRITEABLE了，只需要Context.MODE_PRIVATE也可以完成读写操作。

 

 

 

 

 

 

 

 

示例：

保存或创建一个preference：

package edu.cczu.SimplePreference;  

import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.widget.EditText;  

public class SimplePreferenceActivity extends Activity {
    private EditText nameText;
    private EditText ageText;
    private EditText heightText;
    public static final String PREFER_NAME = "SaveSet";
    public static int MODE = Context.MODE_WORLD_READABLE + Context.MODE_WORLD_WRITEABLE;  

    /** Called when the activity is first created. */
    @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);  

            nameText = (EditText)findViewById(R.id.name);
            ageText = (EditText)findViewById(R.id.age);
            heightText = (EditText)findViewById(R.id.height);
        }  

    @Override
        protected void onStart() {
            // TODO Auto-generated method stub
            super.onStart();
            loadSharedPreferences();
        }  

    private void loadSharedPreferences() {
        // TODO Auto-generated method stub
        SharedPreferences share = getSharedPreferences(PREFER_NAME, MODE);
        String name = share.getString("Name", "Tom");
        int age = share.getInt("Age", 20);
        float height = share.getFloat("Height", 1.81f);  

        nameText.setText(name);
        ageText.setText(String.valueOf(age));
        heightText.setText(String.valueOf(height));
    }  

    @Override
        protected void onStop() {
            // TODO Auto-generated method stub
            super.onStop();
            saveSharedPreferences();
        }  

    private void saveSharedPreferences() {
        // TODO Auto-generated method stub
        SharedPreferences share = getSharedPreferences(PREFER_NAME, MODE);
        SharedPreferences.Editor editor = share.edit();  

        editor.putString("Name", nameText.getText().toString());
        editor.putInt("Age", Integer.parseInt(ageText.getText().toString()));
        editor.putFloat("Height", Float.parseFloat(heightText.getText().toString()));
        editor.commit();
    }
}

其他应用来读取数据：

package edu.cczu.SharePreference;  

import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.pm.PackageManager.NameNotFoundException;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;  

public class SharePreferenceActivity extends Activity {
    public static final String PREFERENCE_PACKAGE = "edu.cczu.SimplePreference";
    public static final String PREFERENCE_NAME = "SaveSet";
    public static int MODE = Context.MODE_WORLD_READABLE + Context.MODE_WORLD_WRITEABLE;
    private TextView labelView;
    private static String TAG = "LIFECYCLE";  

    /** Called when the activity is first created. */
    @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);  

            Context c = null;
            labelView = (TextView)findViewById(R.id.label);    

            try {
                c = this.createPackageContext(PREFERENCE_PACKAGE, Context.CONTEXT_IGNORE_SECURITY);  

            } catch (NameNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }     

            SharedPreferences sharedPreferences = c.getSharedPreferences(PREFERENCE_NAME, MODE);  

            String name = sharedPreferences.getString("Name","Tom");
            int age = sharedPreferences.getInt("Age", 20);
            float height = sharedPreferences.getFloat("Height",1.81f);  

            String msg = "";
            msg += "姓名：" + name + "\n";
            msg += "年龄：" + String.valueOf(age) + "\n";
            msg += "身高：" + String.valueOf(height) + "\n";     

            labelView.setText(msg);     

            Toast.makeText(this, name, Toast.LENGTH_SHORT).show();  

            Log.i(TAG, "(1) onCreate()");
        }  

    @Override
        protected void onStart() {
            // TODO Auto-generated method stub
            super.onStart();
            Log.i(TAG, "(2) onStart()");
        }  

    @Override
        protected void onStop() {
            // TODO Auto-generated method stub
            super.onStop();
            Log.i(TAG, "(8) onStop()");
        }  

    @Override
        protected void onDestroy() {
            // TODO Auto-generated method stub
            super.onDestroy();
            Log.i(TAG, "(9) onDestroy()");
            //System.exit(0);
        }
} 

完