Android Framework中的PolicyManager简介

PolicyManager类位于framework\base\core\java\com\android\internal\policy目录中的PolicyManager.java文件中。PolicyManager主要用于创建Window类、LayoutInflater类和WindowManagerPolicy类，它扮演着简单工厂模式中的工厂类角色，而抽象产品角色由IPolicy接口实现，具体产品角色由Policy类实现。它们的关系如下图所示：

从下面三个类的代码可以看出，都使用了hide注解，因此，这三个类都是不对外公开的API，只限于Framework内部使用。

抽象产品类IPolicy实现如下（IPolicy.java）：

package com.android.internal.policy;import android.content.Context;import android.view.LayoutInflater;import android.view.Window;import android.view.WindowManagerPolicy;/** * {@hide} *//* The implementation of this interface must be called Policy and contained * within the com.android.internal.policy.impl package */public interface IPolicy {    public Window makeNewWindow(Context context);    public LayoutInflater makeNewLayoutInflater(Context context);    public WindowManagerPolicy makeNewWindowManager();}

具体产品类Policy实现如下（Policy.java）：

package com.android.internal.policy.impl;import android.content.Context;import android.util.Log;import com.android.internal.policy.IPolicy;import com.android.internal.policy.impl.PhoneLayoutInflater;import com.android.internal.policy.impl.PhoneWindow;import com.android.internal.policy.impl.PhoneWindowManager;/** * {@hide} */// Simple implementation of the policy interface that spawns the right// set of objectspublic class Policy implements IPolicy {    private static final String TAG = "PhonePolicy";    //需要在Policy类创建时预先加载的一些类    private static final String[] preload_classes = {        "com.android.internal.policy.impl.PhoneLayoutInflater",        "com.android.internal.policy.impl.PhoneWindow",        "com.android.internal.policy.impl.PhoneWindow$1",        "com.android.internal.policy.impl.PhoneWindow$ContextMenuCallback",        "com.android.internal.policy.impl.PhoneWindow$DecorView",        "com.android.internal.policy.impl.PhoneWindow$PanelFeatureState", "com.android.internal.policy.impl.PhoneWindow$PanelFeatureState$SavedState",    };    static {        // 出于性能考虑，在Policy类加载时提前加载会用到的相关类        for (String s : preload_classes) {            try {    //加载指定类到Java虚拟机中，并执行类中的静态代码段                Class.forName(s);            } catch (ClassNotFoundException ex) {                Log.e(TAG, "Could not preload class for phone policy: " + s);            }        }    }    public PhoneWindow makeNewWindow(Context context) {        return new PhoneWindow(context);    }    public PhoneLayoutInflater makeNewLayoutInflater(Context context) {        return new PhoneLayoutInflater(context);    }    //PhoneWindowManager实现了WindowManagerPolicy接口        //这里返回值直接写成WindowManagerPolicy更合理些    public PhoneWindowManager makeNewWindowManager() {        return new PhoneWindowManager();    }}

工厂类PolicyManager实现如下（PolicyManager.java）：

package com.android.internal.policy;import android.content.Context;import android.view.LayoutInflater;import android.view.Window;import android.view.WindowManagerPolicy;import com.android.internal.policy.IPolicy;/** * {@hide} */public final class PolicyManager {    private static final String POLICY_IMPL_CLASS_NAME =        "com.android.internal.policy.impl.Policy";    private static final IPolicy sPolicy;    static {       // 运行时动态装载IPolicy实现类        try {           //加载Policy类的同时会执行其中的静态代码段            Class policyClass = Class.forName(POLICY_IMPL_CLASS_NAME);            sPolicy = (IPolicy)policyClass.newInstance();        } catch (ClassNotFoundException ex) {            throw new RuntimeException(                    POLICY_IMPL_CLASS_NAME + " could not be loaded", ex);        } catch (InstantiationException ex) {            throw new RuntimeException(                    POLICY_IMPL_CLASS_NAME + " could not be instantiated", ex);        } catch (IllegalAccessException ex) {            throw new RuntimeException(                    POLICY_IMPL_CLASS_NAME + " could not be instantiated", ex);        }    }    // 构造函数私有，保证是单例类    private PolicyManager() {}    // The static methods to spawn new policy-specific objects    public static Window makeNewWindow(Context context) {        return sPolicy.makeNewWindow(context);    }    public static LayoutInflater makeNewLayoutInflater(Context context) {        return sPolicy.makeNewLayoutInflater(context);    }    public static WindowManagerPolicy makeNewWindowManager() {        return sPolicy.makeNewWindowManager();    }}


	
				
	
					   
Android Framework中的PolicyManager简介
	  	   
Android Framework中的PolicyManager简介
	  	   
Android Framework中的PolicyManager简介
	  	   
Android Framework中的PolicyManager简介
	  	   
Android Framework中的PolicyManager简介
	  	   
android的Policymanager 作用
	  	   
在android中policymanager
	  	   
android policy源码阅读(1)－policy，PolicyManager
	  	   
Android Framework中的Application Framework层介绍
	  	   
Android Framework中的Application Framework层介绍
	  	   
Android Framework中的Application Framework层介绍
	  	   
android framework中的application framework层
	  	   
Android Framework中的Application Framework层介绍
	  	   
Android Framework中的Application Framework层介绍
	  	   
.NET Framework 3.5 中的功能简介(1)
	  	   
.NET Framework 3.5 中的功能简介
	  	   
PolicyManager.java
	  	   
Android IMF (Input Method Framework) 输入法简介
	     		  
	  	   
哈夫曼树
	  	   
android编译新
	  	   
Haskell 学习笔记
	  	   
扑克牌中学到
	  	   
android离线地图源码
	  	   
Android Framework中的PolicyManager简介
	  	   
ldconfig
	  	   
让电脑开口说话-内容包括任何英文单词和短语
	  	   
3->oracle 后台进程详解
	  	   
Objective-C预处理程序
	  	   
POJ 3663 costume party
	  	   
一个通用的Makefile（针对内核模块类-pro）
	  	   
cent os nfs
	  	   
玩世不恭的简单生活