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):
[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 inte易做图ce must be called Policy and contained
* within the com.android.internal.policy.impl package */
public inte易做图ce IPolicy {
public Window makeNewWindow(Context context);
public LayoutInflater makeNewLayoutInflater(Context context);
public WindowManagerPolicy makeNewWindowManager();
}
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 inte易做图ce must be called Policy and contained
* within the com.android.internal.policy.impl package */
public inte易做图ce 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):
[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 inte易做图ce that spawns the right
// set of objects
public 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();
}
}
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 inte易做图ce that spawns the right
// set of objects
public 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
&
补充:移动开发 , Android ,