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;
    }

}