Glide手写实现之生命周期关联
系列文章
Glide手写实现之资源封装
Glide手写实现之活动缓存
Glide手写实现之内存缓存
Glide手写实现之磁盘缓存
Glide手写实现之生命周期关联
Glide手写实现之网络图片加载实现
Glide手写实现之复用池
生命周期关联
Glide根据传入的上下文环境，比如Activity，FragmentActivity，关联到与之对应的生命周期回调方法。原理是在Activity或者FragmentActivity中添加一个空的Fragment，从而与Activity或者FragmentActivity的生命周期关联。但是传入Context的话， 没法进行生命周期的关联。
Glide
public class Glide {
RequestManagerRetriver retriver;
public Glide(RequestManagerRetriver retriver) {
this.retriver = retriver;
}
public static RequestManager with(FragmentActivity fragmentActivity) {
return getRetriever(fragmentActivity).get(fragmentActivity);
}
public static RequestManager with(Activity activity) {
return getRetriever(activity).get(activity);
}
public static RequestManager with(Context mContext) {
return getRetriever(mContext).get(mContext);
}
/**
* RequestManager有我们的RequestManagerRetriver去创建的
* @return
*/
public static RequestManagerRetriver getRetriever(Context context) {
return Glide.get(context).getRetriver();
}
// Glide 是 new出来的 -- 转变
public static Glide get(Context context) {
return new GlideBuilder().build();
}
/**
* RequestManagerRetriver
* @return
*/
public RequestManagerRetriver getRetriver() {
return retriver;
}
}
public static Glide get(Context context) 这个方法将static的调用转变成非static的调用。
GlideBuilder
public class GlideBuilder {
/**
* 创建Glide
* @return
*/
public Glide build() {
RequestManagerRetriver requestManagerRetriver = new RequestManagerRetriver();
Glide glide = new Glide(requestManagerRetriver);
return glide;
}
}
RequestManager
public class RequestManager {
private final String TAG = RequestManager.class.getSimpleName();
private final String FRAGMENT_ACTIVITY_NAME = "Fragment_Activity_NAME";
private final String ACTIVITY_NAME = "activity_name";
private final int NEXT_HANDLER_MSG = 995465;
private Context requestManagerContext;
private static RequestTargetEngine requestTargetEngine;
// 构造代码块，不用再所有的构造方法里面去实例化了，统一的去写
{
if (requestTargetEngine == null) {
requestTargetEngine = new RequestTargetEngine();
}
}
/**
* 可以管理生命周期 - FragmentActivity是有生命周期方法的(Fragment)
* @param fragmentActivity
*/
FragmentActivity fragmentActivity;
public RequestManager(FragmentActivity fragmentActivity) {
this.requestManagerContext = fragmentActivity;
this.fragmentActivity = fragmentActivity;
// 拿到Fragment
FragmentManager supportFragmentManager = fragmentActivity.getSupportFragmentManager();
Fragment fragment = supportFragmentManager.findFragmentByTag(FRAGMENT_ACTIVITY_NAME);
if (null == fragment) { // 如果等于null，就要去创建Fragment
fragment = new FragmentActivityFragmentManager(requestTargetEngine); // Fragment的生命周期与requestTargetEngine关联起来了
// 添加到 supportFragmentManager
supportFragmentManager.beginTransaction().add(fragment, FRAGMENT_ACTIVITY_NAME).commitAllowingStateLoss(); // 提交
}
// 发送一次Handler
mHandler.sendEmptyMessage(NEXT_HANDLER_MSG);
Fragment fragment2 = supportFragmentManager.findFragmentByTag(FRAGMENT_ACTIVITY_NAME);
Log.d(TAG, "RequestManager: fragment2" + fragment2); // null ： @3 还在排队中，还没有消费
}
/**
* 可以管理生命周期 -- Activity是有生命周期方法的(Fragment)
* @param activity
*/
// todo @2
public RequestManager(Activity activity) {
this.requestManagerContext = activity;
// TODO @3
// 拿到Fragment
android.app.FragmentManager fragmentManager = activity.getFragmentManager();
android.app.Fragment fragment = fragmentManager.findFragmentByTag(ACTIVITY_NAME);
if (null == fragment) {
fragment = new ActivityFragmentManager(requestTargetEngine); // Fragment的生命周期与requestTargetEngine关联起来了
// 添加到管理器 -- fragmentManager.beginTransaction().add.. Handler
fragmentManager.beginTransaction().add(fragment, ACTIVITY_NAME).commitAllowingStateLoss(); // 提交
}
android.app.Fragment fragment2 = fragmentManager.findFragmentByTag(ACTIVITY_NAME);
Log.d(TAG, "RequestManager: fragment2" + fragment2); // null ： @3 还在排队中，还没有消费
// 发送一次Handler
mHandler.sendEmptyMessage(NEXT_HANDLER_MSG);
}
private Handler mHandler = new Handler(new Handler.Callback() {
@Override
public boolean handleMessage(Message msg) {
Fragment fragment2 = fragmentActivity.getSupportFragmentManager().findFragmentByTag(FRAGMENT_ACTIVITY_NAME);
Log.d(TAG, "Handler: fragment2" + fragment2); // 有值 ： 不在排队中，所以有值
return false;
}
});
/**
* 代表无法去管理生命周期 -- 因为Application无法管理
* @param context
*/
public RequestManager(Context context) {
this.requestManagerContext = context;
}
/**
* load 拿到要显示的图片路径
* @param s
* @return
*/
public RequestTargetEngine load(String s) {
// 移除Handler
mHandler.removeMessages(NEXT_HANDLER_MSG);
return requestTargetEngine;
}
}
fragmentManager.beginTransaction().add
之后立马get是拿不到fragment的，因为此时的add任务是发送的handler的队列中的，只有从队列中取出执行了，才会get到fragment。所以通过Handler发送消息的方式拿刚add进去的fragment
RequestManagerRetriver
/**
* 管理RequestManager
*/
public class RequestManagerRetriver {
public RequestManager get(FragmentActivity fragmentActivity) {
return new RequestManager(fragmentActivity);
}
public RequestManager get(Activity activity) {
return new RequestManager(activity);
}
public RequestManager get(Context context) {
return new RequestManager(context);
}
}
ActivityFragmentManager
是与Activity生命周期绑定的辅助类，通过回调接口LifecycleCallback 将生命周期的回调方法暴露给外部。
/**
* Activity 生命周期关联管理
*/
public class ActivityFragmentManager extends Fragment {
public ActivityFragmentManager(){}
private LifecycleCallback lifecycleCallback;
@SuppressLint("ValidFragment")
public ActivityFragmentManager(LifecycleCallback lifecycleCallback) {
this.lifecycleCallback = lifecycleCallback;
}
@Override
public void onStart() {
super.onStart();
if (lifecycleCallback != null) {
lifecycleCallback.glideInitAction();
}
}
@Override
public void onStop() {
super.onStop();
if (lifecycleCallback != null) {
lifecycleCallback.glideStopAction();
}
}
@Override
public void onDestroy() {
super.onDestroy();
if (lifecycleCallback != null) {
lifecycleCallback.glideRecycleAction();
}
}
}
FragmentActivityFragmentManager
是与FragmentActivity生命周期绑定的辅助类，通过回调接口LifecycleCallback 将生命周期的回调方法暴露给外部。
import android.annotation.SuppressLint;
import android.support.v4.app.Fragment;
/**
* FragmentActivity 生命周期关联管理
*/
public class FragmentActivityFragmentManager extends Fragment {
public FragmentActivityFragmentManager(){}
private LifecycleCallback lifecycleCallback;
@SuppressLint("ValidFragment")
public FragmentActivityFragmentManager(LifecycleCallback lifecycleCallback) {
this.lifecycleCallback = lifecycleCallback;
}
@Override
public void onStart() {
super.onStart();
if (lifecycleCallback != null) {
lifecycleCallback.glideInitAction();
}
}
@Override
public void onStop() {
super.onStop();
if (lifecycleCallback != null) {
lifecycleCallback.glideStopAction();
}
}
@Override
public void onDestroy() {
super.onDestroy();
if (lifecycleCallback != null) {
lifecycleCallback.glideRecycleAction();
}
}
}
LifecycleCallback
生命周期的回调接口
public interface LifecycleCallback {
// 生命周期初始化了
public void glideInitAction();
// 生命周期 停止了
public void glideStopAction();
// 生命周期 释放 操作了
public void glideRecycleAction();
}
RequestTargetEngine
图片加载的核心类， 实现了生命周期接口，从而与Activity或者FragmentActivity的生命周期绑定在一起。
/**
* 加载图片资源
*/
public class RequestTargetEngine implements LifecycleCallback {
private final String TAG = RequestTargetEngine.class.getSimpleName();
@Override
public void glideInitAction() {
Log.d(TAG, "glideInitAction: Glide生命周期之 已经开启了 初始化了....");
}
@Override
public void glideStopAction() {
Log.d(TAG, "glideInitAction: Glide生命周期之 已经停止中 ....");
}
@Override
public void glideRecycleAction() {
Log.d(TAG, "glideInitAction: Glide生命周期之 进行释放操作 缓存策略释放操作等 >>>>>> ....");
}
public void into(ImageView imageView) {
}
}