metadata元数据

<receiver android:name=".ViewWidget" android:label="@string/app_name">
   ....
   <meta-data android:name="cn.android" android:value="liming"/>   
   <meta-data android:name=“age" android:value=“30"/> 
   <!-- 使用资源文件中存放的字符串数据 -->
   <meta-data android:name=“other" android:value="@string/other" />
   <!-- 使用资源的ID作为resid的值 -->
   <meta-data android:name=“resid" android:resource="@string/resid" />
</receiver>

上面<meta-data>节点的可以包含在<activity> <activity-alias> <service> <receiver>四个元素中，用于为组件提供名值对数据，组件中可以定义多个<meta-data>节点，这些<meta-data>节点定义的值都会被存放在Bundle对象并作为组件PackageItemInfo.metaData字段值，要访问这些值可以这样做：

 ActivityInfo info = context.getPackageManager().getReceiverInfo(new ComponentName(context, ViewWidget.class), PackageManager.GET_META_DATA);

 String name = info.metaData.getString("cn.android");

 int age = info.metaData.getInt(“age");

 String other= info.metaData.getString("other");

 int id = info.metaData.getInt(“resid");

//如果<meta-data>定义在Activity下，用getPackageManager().getActivityInfo()方法

demo:

1.清单文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.android.hzy.metadata"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="8" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.android.hzy.metadata.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
            <meta-data android:name="name" android:value="火影忍者"/>
            <meta-data android:name="age" android:value="7"/>
            <meta-data android:name="other" android:value="@string/meta"/>
            <!-- key值是一样的  value：引用的是id -->
            <meta-data android:name="res" android:resource="@string/res"/>
        </activity>
    </application>

</manifest>

2.strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">元数据</string>
    <string name="hello_world">Hello world!</string>
    <string name="menu_settings">Settings</string>
    <string name="meta">META</string>
    <string name="res">resourse</string>

</resources>

3.MainActivity

package com.android.hzy.metadata;

import android.app.Activity;
import android.content.ComponentName;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends Activity {

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

    public void get(View v){
        // activity的管理,动态的数据
//        ActivityManager activityManager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
        
        try {
            // 包管理器
            PackageManager pm = getPackageManager();
            ComponentName component = new ComponentName(this,MainActivity.class);
            
            ActivityInfo activityInfo = pm.getActivityInfo(component, PackageManager.GET_META_DATA);
            Bundle bundle = activityInfo.metaData;
            String name = bundle.getString("name");
            int age = bundle.getInt("age");
            String other = bundle.getString("other");
            String res = getString(bundle.getInt("res"));
            
            Log.i("i", " name " + name);
            Log.i("i", " age " + age);
            Log.i("i", " other " + other);
            Log.i("i", " res " + res);
            
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}