Android 之 Metadata简析

在AndroidMainfest.xml中：

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

<manifest xmlns:android=“http://schemas.android.com/apk/res/android”

package=“me.fwl.metadatademo”>

<application

android:allowBackup=“true”

android:icon=“@mipmap/ic_launcher”

android:label=“@string/app_name”

android:supportsRtl=“true”

android:theme=“@style/AppTheme”>

在mainActivity中：

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

private TextView result;

private Context mContext;

private ComponentName cn;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

mContext = this;

cn = this.getComponentName();

result = (TextView) findViewById(R.id.result);

findViewById(R.id.app).setOnClickListener(this);

findViewById(R.id.act).setOnClickListener(this);

findViewById(R.id.rec).setOnClickListener(this);

findViewById(R.id.ser).setOnClickListener(this);

}

@Override

public void onClick(View v) {

switch (v.getId()) {

case R.id.app:

try {

ApplicationInfo appInfo = mContext.getPackageManager().getApplicationInfo(mContext.getPackageName(), PackageManager.GET_META_DATA);

String appMV = appInfo.metaData.getString(“applicationMetadataKey”);

result.setText(appMV);

} catch (PackageManager.NameNotFoundException e) {

e.printStackTrace();

}

break;

case R.id.act:

try {

ActivityInfo actInfo = mContext.getPackageManager().getActivityInfo(cn, PackageManager.GET_META_DATA);

String actMV = actInfo.metaData.getString(“activityMetadataKey”);

result.setText(actMV);

} catch (PackageManager.NameNotFoundException e) {

e.printStackTrace();

}

break;

case R.id.rec:

ComponentName recCn = new ComponentName(mContext, MainReceiver.class);

try {

ActivityInfo recInfo = mContext.getPackageManager().getReceiverInfo(recCn, PackageManager.GET_META_DATA);

String recMV = recInfo.metaData.getString(“receiverMetadataKey”);

result.setText(recMV);

} catch (PackageManager.NameNotFoundException e) {

e.printStackTrace();

}

break;

case R.id.ser:

ComponentName serCn = new ComponentName(mContext, MainService.class);

try {

ServiceInfo serInfo = mContext.getPackageManager().getServiceInfo(serCn, PackageManager.GET_META_DATA);

String serMV = serInfo.metaData.getString(“serviceMetadataKey”);

result.setText(serMV);

} catch (PackageManager.NameNotFoundException e) {

e.printStackTrace();

}

break;

}

}

}

运行结果：

05-22 21:21:04.624 14238-14238/com.fedming.notches D/fdm: meta_app : value from meta_app

05-22 21:21:04.625 14238-14238/com.fedming.notches D/fdm: meta_act_id : 2131427357, meta_act_string : Notche

可以看到，我们在manifest中配置了，并在Activity中获取了这些配置的信息。

我们点进去看一下源码，metaData到底是什么？本质上就是个Bundle。

实际应用

在系统属性配置、配置屏幕支持比例，配置SearchableActivity等方面都有运用。

分享时：

<meta-data

android:name=“UMENG_APPKEY”

android:value=“000011111” />

配置桌面快捷方式时：

<meta-data

android:name=“android.app.shortcuts”

android:resource=“@xml/shortcuts” />

屏幕适配时：

<meta-data

android:name=“android.max_aspect”

android:value=“2.1” />

配置地图API时：