元数据(meta-data)

本章所介绍的元数据的知识,可能在定制系统时会用到.因为那是后需要修改底层框架的一些内容

一、元数据的定义

在AndroidManifest.xml中如下书写：

 <activity
            android:name="com.njupt.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="java_ns" android:value="章泽天11" />
            <meta-data android:name="balance" android:value="45000"/>
            <meta-data android:name="c++_ns" android:value="@string/second"/>
            <meta-data android:name="wife" android:resource="@string/first"/>
        </activity>

二、获取元数据

MainActivity

package com.njupt.metadata;
 
import android.os.Bundle;
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.view.Menu;
import android.view.View;
 
public class MainActivity extends Activity {
 
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
	}
 
	public void get(View v){
		try {
			PackageManager pm = getPackageManager();
			ComponentName component = new ComponentName(this,MainActivity.class);
			ActivityInfo info = pm.getActivityInfo(component,PackageManager.GET_META_DATA);
			Bundle bundle = info.metaData;
			String java_ns = bundle.getString("java_ns");
			int balance = bundle.getInt("balance");
			String c_ns = bundle.getString("c++_ns");
			String wife = getString(bundle.getInt("wife"));
 
			System.out.println("java_ns: " + java_ns + ", balance: " + balance +",c_ns: " + c_ns +",wife: " + wife);
		} catch (NameNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}
 
}