android 获取application和activity下meta-data中的值

        meta-data在AndroidManifest中是以键值对的形式存在的，可以将meta-data放在application根节点下，也可以放在某个activity节点下。因为存放的位置不同，因此获取value时也要使用对应的方法，下面是我写的一个小测试。

代码如下：

先是在AndroidManifest中的application和mainActivity下添加两个meta-data属性。

 <application
     android:allowBackup="true"
     android:icon="@drawable/ic_launcher"
     android:label="@string/app_name"
     android:theme="@style/AppTheme" >
     <meta-data
         android:name="com.lzy.test"
         android:value="测试" />

     <activity
         android:name=".MainActivity"
         android:label="@string/app_name" >
         <meta-data
             android:name="com.example.metatest.MainActivity.com.lzy.activity.test"
             android:value="Activity测试" />

         <intent-filter>
             <action android:name="android.intent.action.MAIN" />

             <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
     </activity>
 </application>

接下来在mainActivity中来获取这两个属性的值。

 package com.example.metatest;

 import android.app.Activity;
 import android.content.ComponentName;
 import android.content.pm.ActivityInfo;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.os.Bundle;
 import android.util.Log;
 import android.widget.Toast;

 /**
  * meta 测试
  *
  * @author Administrator
  *
  */

 public class MainActivity extends Activity {

     public static final String TEST = "com.lzy.test";

     public static final String ACTIVITYTEST = MainActivity.class.getName()+".com.lzy.activity.test";

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

         String test = getMetaDataStringApplication(TEST, null);

         String activityTest = getMetaDataStringFromActivity(ACTIVITYTEST, null);

         Toast.makeText(this, test+"--"+activityTest, Toast.LENGTH_LONG).show();
     }

     /**
      * 根据key从Application中返回的Bundle中获取value
      *
      * @param key
      * @param defValue
      * @return
      */
     private String getMetaDataStringApplication(String key, String defValue) {
         Bundle bundle = getAppMetaDataBundle(getPackageManager(), getPackageName());
         if (bundle != null && bundle.containsKey(key)) {
             return bundle.getString(key);
         }
         return defValue;
     }

     /**
      * 获取Application中的meta-data.
      *
      * @param packageManager
      * @param packageName
      * @return
      */
     private Bundle getAppMetaDataBundle(PackageManager packageManager,
             String packageName) {
         Bundle bundle = null;
         try {
             ApplicationInfo ai = packageManager.getApplicationInfo(packageName,
                     PackageManager.GET_META_DATA);
             bundle = ai.metaData;
         } catch (NameNotFoundException e) {
             Log.e("getMetaDataBundle", e.getMessage(), e);
         }
         return bundle;
     }

     /**
      * 根据key从Activity中返回的Bundle中获取value
      *
      * @param key
      * @param defValue
      * @return
      */
     private String getMetaDataStringFromActivity(String key, String defValue) {
         Bundle bundle = getActivityMetaDataBundle(getPackageManager(), getComponentName());
         if (bundle != null && bundle.containsKey(key)) {
             return bundle.getString(key);
         }
         return defValue;
     }

     /**
      * 获取Activity中的meta-data.
      *
      * @param packageManager
      * @param component
      * @return
      */
     private Bundle getActivityMetaDataBundle(PackageManager packageManager, ComponentName component) {
         Bundle bundle = null;
         try {
             ActivityInfo ai = packageManager.getActivityInfo(component,
                     PackageManager.GET_META_DATA);
             bundle = ai.metaData;
         } catch (NameNotFoundException e) {
             Log.e("getMetaDataBundle", e.getMessage(), e);
         }

         return bundle;
     }

 }

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