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仿99健康网网站源码,繁昌网站建设,做食物外网视频网站,网站初期建设方案目录 一#xff0c;介绍 二#xff0c;使用 三#xff0c;源码分析思路 四#xff0c;with源码分析 五#xff0c;模拟Glide生命周期管理 一#xff0c;介绍 Glide目前是安卓最主流的加载图片的框架#xff0c;也是源码最为复杂的框架之一。 要想完完全全吃透Glide的源… 目录 一介绍 二使用 三源码分析思路 四with源码分析 五模拟Glide生命周期管理 一介绍 Glide目前是安卓最主流的加载图片的框架也是源码最为复杂的框架之一。 要想完完全全吃透Glide的源码可能需要半年甚至更多的时间。 但是如果分析过Glide的源码不仅对我们的架构能力有很大提高也会对面试中的关于Glide的问题知其然更知其所以然。 Glide的精髓在于它的生命周期的管理和缓存策略。 二使用 Glide的使用及其简单 // 项目的build.gradle添加依赖implementation com.github.bumptech.glide:glide:4.11.0annotationProcessor com.github.bumptech.glide:compiler:4.11.0 在清单文件添加网络权限 uses-permission android:nameandroid.permission.INTERNET/ 布局文件很简单就一个imageview ?xml version1.0 encodingutf-8? androidx.constraintlayout.widget.ConstraintLayoutxmlns:androidhttp://schemas.android.com/apk/res/androidxmlns:apphttp://schemas.android.com/apk/res-autoxmlns:toolshttp://schemas.android.com/toolsandroid:layout_widthmatch_parentandroid:layout_heightmatch_parenttools:context.MainActivityImageViewandroid:idid/ivandroid:layout_widthmatch_parentandroid:layout_heightmatch_parent//androidx.constraintlayout.widget.ConstraintLayout 使用 class MainActivity : AppCompatActivity() {//图片urlprivate val url https://q7.itc.cn/q_70/images03/20240714/93ce0113753a4ff4b5f4e48f27ed3739.jpegoverride fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)setContentView(R.layout.activity_main)val iv findViewByIdImageView(R.id.iv)Glide.with(this).load(url).into(iv)} } 效果 三源码分析思路 Glide的源码分析我们可以从使用角度拆分为三部分去分析。 class MainActivity : AppCompatActivity() {//图片urlprivate val url https://q7.itc.cn/q_70/images03/20240714/93ce0113753a4ff4b5f4e48f27ed3739.jpegoverride fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)setContentView(R.layout.activity_main)val iv findViewByIdImageView(R.id.iv)//第一步 调用with 得到RequestManagerval requestManager:RequestManager Glide.with(this)//第二步 RequestManager调用load 得到requestBuliderval requestBulider:RequestBuilderDrawable requestManager.load(url)//第三步 requestBulider调用intorequestBulider.into(iv)} } 这样拆分的话思路会比较清晰。 四with源码分析 首先我们看一下with的源码 NonNull public static RequestManager with(NonNull Context context) {return getRetriever(context).get(context); }NonNull public static RequestManager with(NonNull Activity activity) {return getRetriever(activity).get(activity); }NonNull public static RequestManager with(NonNull FragmentActivity activity) {return getRetriever(activity).get(activity); }NonNull public static RequestManager with(NonNull Fragment fragment) {return getRetriever(fragment.getContext()).get(fragment); }SuppressWarnings(deprecation) Deprecated NonNull public static RequestManager with(NonNull android.app.Fragment fragment) {return getRetriever(fragment.getActivity()).get(fragment); }NonNull public static RequestManager with(NonNull View view) {return getRetriever(view.getContext()).get(view); } 它可以接受的参数类型很多确保多种场景下的使用 然后继续往下看getRetriever这个函数 NonNull private static RequestManagerRetriever getRetriever(Nullable Context context) {// Context could be null for other reasons (ie the user passes in null), but in practice it will// only occur due to errors with the Fragment lifecycle.Preconditions.checkNotNull(context,You cannot start a load on a not yet attached View or a Fragment where getActivity() returns null (which usually occurs when getActivity() is called before the Fragment is attached or after the Fragment is destroyed).);return Glide.get(context).getRequestManagerRetriever(); } 判空不用看直接看get(context)这个函数 NonNull public static Glide get(NonNull Context context) {if (glide null) {GeneratedAppGlideModule annotationGeneratedModule getAnnotationGeneratedGlideModules(context.getApplicationContext());synchronized (Glide.class) {if (glide null) {checkAndInitializeGlide(context, annotationGeneratedModule);}}}return glide; } 这个就是我们熟悉的双重检测单例模式不了解的可以参考文章Android 设计模式–单例模式_android开发饿汉单例-CSDN博客 然后我们看看 checkAndInitializeGlide(context, annotationGeneratedModule) GuardedBy(Glide.class) private static void checkAndInitializeGlide(NonNull Context context, Nullable GeneratedAppGlideModule generatedAppGlideModule) {// In the thread running initGlide(), one or more classes may call Glide.get(context).// Without this check, those calls could trigger infinite recursion.if (isInitializing) {throw new IllegalStateException(You cannot call Glide.get() in registerComponents(), use the provided Glide instance instead);}isInitializing true;initializeGlide(context, generatedAppGlideModule);isInitializing false; } 这里好像没有什么具体的信息我们接着往下看initializeGlide(context,generatedAppGlideModule)这个函数 GuardedBy(Glide.class) private static void initializeGlide(NonNull Context context, Nullable GeneratedAppGlideModule generatedAppGlideModule) {initializeGlide(context, new GlideBuilder(), generatedAppGlideModule); } 好的依然继续往下看initializeGlide(context, new GlideBuilder(), generatedAppGlideModule) GuardedBy(Glide.class) SuppressWarnings(deprecation) private static void initializeGlide(NonNull Context context,NonNull GlideBuilder builder,Nullable GeneratedAppGlideModule annotationGeneratedModule) {//获取应用级别的上下文Context applicationContext context.getApplicationContext();Listcom.bumptech.glide.module.GlideModule manifestModules Collections.emptyList();if (annotationGeneratedModule null || annotationGeneratedModule.isManifestParsingEnabled()) {manifestModules new ManifestParser(applicationContext).parse();}if (annotationGeneratedModule ! null !annotationGeneratedModule.getExcludedModuleClasses().isEmpty()) {SetClass? excludedModuleClasses annotationGeneratedModule.getExcludedModuleClasses();Iteratorcom.bumptech.glide.module.GlideModule iterator manifestModules.iterator();while (iterator.hasNext()) {com.bumptech.glide.module.GlideModule current iterator.next();if (!excludedModuleClasses.contains(current.getClass())) {continue;}if (Log.isLoggable(TAG, Log.DEBUG)) {Log.d(TAG, AppGlideModule excludes manifest GlideModule: current);}iterator.remove();}}if (Log.isLoggable(TAG, Log.DEBUG)) {for (com.bumptech.glide.module.GlideModule glideModule : manifestModules) {Log.d(TAG, Discovered GlideModule from manifest: glideModule.getClass());}} //通过注解生成的代码拿到 RequestManagerFactoryRequestManagerRetriever.RequestManagerFactory factory annotationGeneratedModule ! null? annotationGeneratedModule.getRequestManagerFactory(): null; //将拿到的工厂添加到 GlideBuilderbuilder.setRequestManagerFactory(factory);for (com.bumptech.glide.module.GlideModule module : manifestModules) {module.applyOptions(applicationContext, builder);}if (annotationGeneratedModule ! null) {annotationGeneratedModule.applyOptions(applicationContext, builder);} //通过 Builder 建造者模式构建出 Glide 实例对象Glide glide builder.build(applicationContext); //注册组件回调for (com.bumptech.glide.module.GlideModule module : manifestModules) {try {module.registerComponents(applicationContext, glide, glide.registry);} catch (AbstractMethodError e) {throw new IllegalStateException(Attempting to register a Glide v3 module. If you see this, you or one of your dependencies may be including Glide v3 even though youre using Glide v4. Youll need to find and remove (or update) the offending dependency. The v3 module name is: module.getClass().getName(),e);}}if (annotationGeneratedModule ! null) {annotationGeneratedModule.registerComponents(applicationContext, glide, glide.registry);}applicationContext.registerComponentCallbacks(glide); //将构建出来的 glide 赋值给 Glide 的静态变量Glide.glide glide; } 这个函数里面的信息量是非常大的主要是进行了一系列的初始化操作通过 Builder 建造者模式构建出 Glide 实例对象接着我们看看builder模式进行了哪些构建 NonNull Glide build(NonNull Context context) { //网络请求的线程池if (sourceExecutor null) {sourceExecutor GlideExecutor.newSourceExecutor();} //本地磁盘缓存的线程池if (diskCacheExecutor null) {diskCacheExecutor GlideExecutor.newDiskCacheExecutor();} //加载图片动画的一个线程池if (animationExecutor null) {animationExecutor GlideExecutor.newAnimationExecutor();} //对图片加载到内存的一个计算if (memorySizeCalculator null) {memorySizeCalculator new MemorySizeCalculator.Builder(context).build();} //默认网络连接监控的工厂if (connectivityMonitorFactory null) {connectivityMonitorFactory new DefaultConnectivityMonitorFactory();} //Bitmap 对象池if (bitmapPool null) {int size memorySizeCalculator.getBitmapPoolSize();if (size 0) {bitmapPool new LruBitmapPool(size);} else {bitmapPool new BitmapPoolAdapter();}} //数组对象池if (arrayPool null) {arrayPool new LruArrayPool(memorySizeCalculator.getArrayPoolSizeInBytes());} //资源内存缓存if (memoryCache null) {memoryCache new LruResourceCache(memorySizeCalculator.getMemoryCacheSize());} //磁盘缓存的工厂if (diskCacheFactory null) {diskCacheFactory new InternalCacheDiskCacheFactory(context);} //构建执行缓存策略跟线程池的引擎if (engine null) {engine new Engine(memoryCache,diskCacheFactory,diskCacheExecutor,sourceExecutor,GlideExecutor.newUnlimitedSourceExecutor(),animationExecutor,isActiveResourceRetentionAllowed);}if (defaultRequestListeners null) {defaultRequestListeners Collections.emptyList();} else {defaultRequestListeners Collections.unmodifiableList(defaultRequestListeners);} //RequestManagerRetriever 请求管理类RequestManagerRetriever requestManagerRetriever new RequestManagerRetriever(requestManagerFactory);return new Glide(context,engine,memoryCache,bitmapPool,arrayPool,requestManagerRetriever,connectivityMonitorFactory,logLevel,defaultRequestOptionsFactory,defaultTransitionOptions,defaultRequestListeners,isLoggingRequestOriginsEnabled,isImageDecoderEnabledForBitmaps); } 这里就完成了Glide的构建。 然后我们回到最开始的getRetriever(activity).get(activity)看看这个函数里面都干了些什么 NonNull public RequestManager get(NonNull FragmentActivity activity) { //首先判断当前是否在子线程中if (Util.isOnBackgroundThread()) { //在子线程中 就通过Application级别的上下文加载return get(activity.getApplicationContext());} else { //检查Activity是否已经销毁assertNotDestroyed(activity); //拿到当前activity的fragmentmanagerFragmentManager fm activity.getSupportFragmentManager(); //生成一个fragment 然后绑定一个请求管理类RequestManagerreturn supportFragmentGet(activity, fm, /parentHint/ null, isActivityVisible(activity));} } 看到这里我们就应该意识到一个问题如果我们在子线程中去调用Glide的话就会使用应用级别的上下文去加载图片这样大量使用可能会导致内存泄漏。 然后在主线程中使用就是Glide的精髓之一了加载一个透明fragment来感应当前页面的生命周期的变化。 接着看看supportFragmentGet是怎么实现的 NonNull private RequestManager supportFragmentGet(NonNull Context context,NonNull FragmentManager fm,Nullable Fragment parentHint,boolean isParentVisible) { //在当前的 Acitivty 添加一个 Fragment 用于管理请求的生命周期SupportRequestManagerFragment current getSupportRequestManagerFragment(fm, parentHint, isParentVisible); //拿到当前请求的管理类RequestManager requestManager current.getRequestManager(); //如果为空 就创建一个if (requestManager null) {// TODO(b/27524013): Factor out this Glide.get() call.Glide glide Glide.get(context);requestManager factory.build(glide, current.getGlideLifecycle(), current.getRequestManagerTreeNode(), context);current.setRequestManager(requestManager);}return requestManager; } 这里就是添加一个fragment管理生命周期。然后返回一个RequestManager对象。 接下来再具体看看getSupportRequestManagerFragment是怎么添加的 NonNull private SupportRequestManagerFragment getSupportRequestManagerFragment(NonNull final FragmentManager fm, Nullable Fragment parentHint, boolean isParentVisible) { //通过tag拿到fragment实例 避免重复SupportRequestManagerFragment current (SupportRequestManagerFragment) fm.findFragmentByTag(FRAGMENT_TAG); //没有实例的话 就去缓存找if (current null) {current pendingSupportRequestManagerFragments.get(fm); //缓存也没有 就创建一个if (current null) {current new SupportRequestManagerFragment();current.setParentFragmentHint(parentHint);if (isParentVisible) {current.getGlideLifecycle().onStart();}pendingSupportRequestManagerFragments.put(fm, current);fm.beginTransaction().add(current, FRAGMENT_TAG).commitAllowingStateLoss();handler.obtainMessage(ID_REMOVE_SUPPORT_FRAGMENT_MANAGER, fm).sendToTarget();}}return current; } 这里主要是拿到fragment实例。 从上面我们可以看出Glide主要是做了一些初始化的工作缓存线程池复用池的构建等等。 然后绑定了一个fragment来管理生命周期 with的源码差不多就是这些可能比较繁琐但是不像rxjava那样绕来绕去的主线还是比较清晰的。 五模拟Glide生命周期管理 首先创建一个接口监听生命周期回调 public interface LifecycleListener {void onCreate();void onStart();void onStop();void onDestroy();} 然后创建一个用来管理生命周期监听的接口 public interface Lifecycle {void addListener(NonNull LifecycleListener listener);void removeListener(NonNull LifecycleListener listener);} 通过上面的分析我们知道Glide传入的上下文有应用级别的和非应用级别的。所以我们首先创建一个应用级别的Lifecycle public class ApplicationLifecycle implements Lifecycle {Overridepublic void addListener(NonNull LifecycleListener listener) {/*** APP启动的时候执行onCreate*/listener.onCreate();}Overridepublic void removeListener(NonNull LifecycleListener listener) {//APP销毁的时候啥也不用做了} } 然后创建一个非应用级别的lifecycle public class ActivityFragmentLifecycle implements Lifecycle {private final SetLifecycleListener lifecycleListeners Collections.newSetFromMap(new WeakHashMapLifecycleListener, Boolean());private boolean isStarted; private boolean isDestroyed; Overridepublic void addListener(NonNull LifecycleListener listener) {lifecycleListeners.add(listener);if (isDestroyed) {listener.onDestroy();} else if (isStarted) {listener.onCreate();} else {listener.onStop(); }}Overridepublic void removeListener(NonNull LifecycleListener listener) {lifecycleListeners.remove(listener);}void onStart() {isStarted true;for (LifecycleListener lifecycleListener : lifecycleListeners) {lifecycleListener.onCreate();}}void onStop() {isStarted false;for (LifecycleListener lifecycleListener : lifecycleListeners) {lifecycleListener.onStop();}}void onDestroy() {isDestroyed true;for (LifecycleListener lifecycleListener : lifecycleListeners) {lifecycleListener.onDestroy();}} } 创建一个具体的RequestManager 管理生命周期 public class RequestManager implements LifecycleListener {private Lifecycle lifecycle;public RequestManager(Lifecycle lifecycle, Context applicationContext) {this.lifecycle lifecycle;this.lifecycle.addListener(this);}Overridepublic void onCreate() {Log.d(LOG.TAG, yh—–onCreate);}Overridepublic void onStart() {Log.d(LOG.TAG, yh—–onStart);}Overridepublic void onStop() {Log.d(LOG.TAG, yh—–onStop);}Overridepublic void onDestroy() {Log.d(LOG.TAG, yh—–onDestroy);this.lifecycle.removeListener(this);} } 创建一个空白的fragment public class RequestManagerFragment extends Fragment {private final ActivityFragmentLifecycle lifecycle;Nullableprivate RequestManager requestManager;public RequestManagerFragment() {this(new ActivityFragmentLifecycle());}VisibleForTestingSuppressLint(ValidFragment)public RequestManagerFragment(NonNull ActivityFragmentLifecycle lifecycle) {this.lifecycle lifecycle;}public void setRequestManager(Nullable RequestManager requestManager) {this.requestManager requestManager;}NonNullpublic ActivityFragmentLifecycle getGlideLifecycle() {return lifecycle;}Overridepublic void onAttach(NonNull Context context) {super.onAttach(context);this.lifecycle.addListener(requestManager);}Nullablepublic RequestManager getRequestManager() {return requestManager;}Overridepublic void onDetach() {super.onDetach();}Overridepublic void onStart() {super.onStart();lifecycle.onStart();}Overridepublic void onStop() {super.onStop();lifecycle.onStop();}Overridepublic void onDestroy() {super.onDestroy();lifecycle.onDestroy();} } 简单写一个Glide管理类 public class Glide {private static volatile Glide glide;NonNullpublic static Glide get(NonNull Context context) {if (glide null) {synchronized (Glide.class) {if (glide null) {glide new Glide();}}}return glide;}NonNullpublic static RequestManager with(NonNull Context context) {return new RequestManager(new ActivityFragmentLifecycle(),context);}NonNullpublic static RequestManager withApplication(NonNull Context context) {return new RequestManager(new ApplicationLifecycle(),context);}}使用也很简单 public class DemoActivity extends AppCompatActivity {Overrideprotected void onCreate(Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);Glide.with(this);Glide.withApplication(this.getApplicationContext());} } 这样当DemoActivity创建时会创建一个ActivityFragmentLifecycle执行它的onStart方法从而调用RequestManager的onStart方法onDestory也是同样的道理。这样就实现了生命周期的检测。这里只是简单写下有助于理解Glide内部是怎么做的。 关于load和into以及缓存机制 改天再写。