概述
本章节从源码层面讲述Glide(3.7.0)的一些用法。
首先使用Glide最常用的使用是
Glide.with(this).load(url).into(imageView);下面我们依次看一下with方法+load方法+into方法。
with方法源码
首先，Glide框架with方法有五个重载的方法。
1.传参Context
public static RequestManager with(Context context) {
RequestManagerRetriever retriever = RequestManagerRetriever.get();
return retriever.get(context);
}内部获取RequestManager对象
public RequestManager get(Context context) {
if (context == null) {
throw new IllegalArgumentException("You cannot start a load on a null Context");
} else if (Util.isOnMainThread() && !(context instanceof Application)) {
if (context instanceof FragmentActivity) {
return get((FragmentActivity) context);
} else if (context instanceof Activity) {
return get((Activity) context);
} else if (context instanceof ContextWrapper) {
return get(((ContextWrapper) context).getBaseContext());
}
}
return getApplicationManager(context);
}也就是说，传参Context时
<1> 参数Context为空 抛出异常。
<2> 主线程操作&传参Context不是Application 分别获取Context类型，比如Activity或者Fragment。
<3> 子线程获取或者传参Context是Application 通过Application获取RequestManager对象。
小结1
传参Context时，如果是子线程中操作或者参数Context是Application 则通过Application获取RequestManager对象。也就是说 这种情况下 Glide的生命周期和应用程序的生命周期是同步的，如果应用程序关闭的话，Glide的加载也会同时终止。
2.传参Activity
public static RequestManager with(Activity activity) {
RequestManagerRetriever retriever = RequestManagerRetriever.get();
return retriever.get(activity);
}内部获取RequestManager对象
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public RequestManager get(Activity activity) {
if (Util.isOnBackgroundThread() || Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB) {
return get(activity.getApplicationContext());
} else {
assertNotDestroyed(activity);
android.app.FragmentManager fm = activity.getFragmentManager();
return fragmentGet(activity, fm);
}
}也就是说，传参Activity时
<1> 子线程中操作或者系统版本小于11(Android 3.0) 通过Application获取RequestManager对象。
<2> 主线程中操作并且Android版本在3.0以上 首先校验当前Activity的状态。
@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
private static void assertNotDestroyed(Activity activity) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1 && activity.isDestroyed()) {
throw new IllegalArgumentException("You cannot start a load for a destroyed activity");
}
}Activity处于Destory时，抛出You cannot start a load for a destroyed activity异常。
然后创建一个临时的Fragment。返回RequestManager对象。那么这里为什么要添加一个隐藏的Fragment呢？因为Glide需要知道加载的生命周期。
小结2
传参Activity时，如果在子线程中操作或者Android版本小于3.0(现在可以忽略)。则使用Application获取RequestManager对象。其他情况使用Activity获取RequestManager对象。注意此时需要判断Activity的状态。
3.传参FragmentActivity
public static RequestManager with(FragmentActivity activity) {
RequestManagerRetriever retriever = RequestManagerRetriever.get();
return retriever.get(activity);
}内部获取RequestManager对象
public RequestManager get(FragmentActivity activity) {
if (Util.isOnBackgroundThread()) {
return get(activity.getApplicationContext());
} else {
assertNotDestroyed(activity);
FragmentManager fm = activity.getSupportFragmentManager();
return supportFragmentGet(activity, fm);
}
}和传参Activity一致，这里不再赘述。
4.传参android.app.Fragment
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public static RequestManager with(android.app.Fragment fragment) {
RequestManagerRetriever retriever = RequestManagerRetriever.get();
return retriever.get(fragment);
}内部获取RequestManager对象
@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
public RequestManager get(android.app.Fragment fragment) {
if (fragment.getActivity() == null) {
throw new IllegalArgumentException("You cannot start a load on a fragment before it is attached");
}
if (Util.isOnBackgroundThread() || Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1) {
return get(fragment.getActivity().getApplicationContext());
} else {
android.app.FragmentManager fm = fragment.getChildFragmentManager();
return fragmentGet(fragment.getActivity(), fm);
}
}也就是说，传参android.app.Fragment时
<1> 如果当前Fragment的宿主Activity为空 抛出异常。
<2> 如果子线程操作或者Android版本小于3.0(现在可以忽略)。通过Application获取RequestManager对象。
<3> 否则 获取getChildFragmentManager 然后获取RequestManager对象。
小结3
传参android.app.Fragment时，如果在子线程中操作或者Android版本小于3.0(现在可以忽略)。则使用Application获取RequestManager对象。其他情况通过获取getChildFragmentManager获取RequestManager对象。
5.传参Fragment
public static RequestManager with(Fragment fragment) {
RequestManagerRetriever retriever = RequestManagerRetriever.get();
return retriever.get(fragment);
}内部获取RequestManager对象
public RequestManager get(Fragment fragment) {
if (fragment.getActivity() == null) {
throw new IllegalArgumentException("You cannot start a load on a fragment before it is attached");
}
if (Util.isOnBackgroundThread()) {
return get(fragment.getActivity().getApplicationContext());
} else {
FragmentManager fm = fragment.getChildFragmentManager();
return supportFragmentGet(fragment.getActivity(), fm);
}
}和传参android.app.Fragment一致，这里不再赘述。
五个重载方法仅仅是参数不同，都是获取RequestManagerRetriever对象，然后通过入参传参的参数通过RequestManagerRetriever对象获取RequestManager对象。
总结
通过with方法源码可知。
<1> 子线程中操作Glide。无论传参是什么类型，都会通过Application获取RequestManager对象。此时Glide的生命周期和应用程序的生命周期是同步的，如果应用程序关闭的话，Glide的加载也会同时终止。
<2> 主线程中操作Glide。传参不同会有不同的获取RequestManager对象的方式。
<3> 使用Glide时，最好不要在子线程中操作，因为它的生命周期会和Application一样。这样有可能造成Activity不能被回收。比如Into方法拿到了ImageView的引用等等。
<4> 使用Glide时，传参非Application时，尤其是Activity时，最好判断一下Activity的状态。
<5> 这里说的子线程操作Glide。仅仅指 使用with方法获取RequestManager对象。比如
RequestManager requestManager = Glide.with(this);而不是说操作整个的流程。比如
Glide.with(this).load(url).into(imageView);因为into方法 加载图片到View时，会校验线程的。如果不是主线程会抛出异常。这个下面会讲解的。这里举例说明
代码
public class GlideActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_glide);
ImageView imageView = findViewById(R.id.activity_glide_imageview);
String url = "";
new Thread(new Runnable() {
@Override
public void run() {
Glide.with(GlideActivity.this).load(url).into(imageView);
}
}).start();
}
}报错
E/AndroidRuntime: FATAL EXCEPTION: Thread-6
Process: com.wjn.networkdemo, PID: 12291
java.lang.IllegalArgumentException: You must call this method on the main thread
at com.bumptech.glide.util.Util.assertMainThread(Util.java:135)
at com.bumptech.glide.GenericRequestBuilder.into(GenericRequestBuilder.java:676)
at com.bumptech.glide.DrawableRequestBuilder.into(DrawableRequestBuilder.java:448)
at com.wjn.networkdemo.glide.GlideActivity$1.run(GlideActivity.java:24)
at java.lang.Thread.run(Thread.java:764)
其中 You must call this method on the main thread 错误异常就是into方法中报出的。
<6> with方法返回RequestManager对象。此方法可以在子线程中执行。
load方法源码
load方法也有很多重载的方法，对应显示什么方式的图片
1.显示网络图片
public DrawableTypeRequest<String> load(String string) {
return (DrawableTypeRequest<String>) fromString().load(string);
}
2.显示Uri图片(相机相册)
public DrawableTypeRequest<Uri> load(Uri uri) {
return (DrawableTypeRequest<Uri>) fromUri().load(uri);
}
3.显示File图片
public DrawableTypeRequest<File> load(File file) {
return (DrawableTypeRequest<File>) fromFile().load(file);
}
4.显示Integer图片(项目中的map或者drawable)
public DrawableTypeRequest<Integer> load(Integer resourceId) {
return (DrawableTypeRequest<Integer>) fromResource().load(resourceId);
}
5.显示URL图片(其他应用提供的)
@Deprecated
public DrawableTypeRequest<URL> load(URL url) {
return (DrawableTypeRequest<URL>) fromUrl().load(url);
}
6.显示byte[](Base64)图片
public DrawableTypeRequest<byte[]> load(byte[] model) {
return (DrawableTypeRequest<byte[]>) fromBytes().load(model);
}
这里我们分析源码只分析加载网络图片的load方法。
return (DrawableTypeRequest<String>) fromString().load(string);fromString()方法源码
public DrawableTypeRequest<String> fromString() {
return loadGeneric(String.class);
}loadGeneric()方法源码
private <T> DrawableTypeRequest<T> loadGeneric(Class<T> modelClass) {
}load()方法源码
public DrawableRequestBuilder<ModelType> load(ModelType model) {
super.load(model);
return this;
}也就是说load()方法，最终返回DrawableRequestBuilder对象。因为最后还要执行into()方法，所以load()方法源码我们先讲到这里。
into方法源码
into方法有两个重载的方法，对应显示图片在什么控件上
1.显示在ImageView上
public Target<TranscodeType> into(ImageView view) {
}
2.显示在自定义的View上
public <Y extends Target<TranscodeType>> Y into(Y target) {
}显示在ImageView上就不多说了，下面看一下怎么显示在自定义的View上。
其实，这两个重载的into方法。Glide内部是有内部调用的，即into ImageView类型时，其实内部会生成一个Target对象。然后调用into Target类型的方法。
Glide的所有Target
这其中ViewTarget的功能更加广泛。我们可以使用它在任意的View上显示加载的图片。
自定义ViewTarget
public class MyLayout extends RelativeLayout {
private ViewTarget<MyLayout, GlideDrawable> mViewTarget;
public MyLayout(Context context) {
super(context);
initViewTarget();
}
public MyLayout(Context context, AttributeSet attrs) {
super(context, attrs);
initViewTarget();
}
/**
* 初始化ViewTarget
*/
private void initViewTarget() {
mViewTarget = new ViewTarget<MyLayout, GlideDrawable>(this) {
@Override
public void onResourceReady(GlideDrawable resource, GlideAnimation glideAnimation) {
MyLayout myLayout = getView();
myLayout.setBackground(resource);
}
};
}
/**
* 外界使用提供获取ViewTarget对象的方法
*/
public ViewTarget<MyLayout, GlideDrawable> getTarget() {
return mViewTarget;
}
}
使用
public class GlideActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_glide);
MyLayout myLayout = findViewById(R.id.activity_glide_layout);
String url = "";
Glide.with(this).load(url).into(myLayout.getTarget());
}
}
布局
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".glide.GlideActivity">
<com.wjn.networkdemo.glide.MyLayout
android:id="@+id/activity_glide_layout"
android:layout_width="match_parent"
android:layout_height="400dp"
tools:ignore="MissingConstraints">
</com.wjn.networkdemo.glide.MyLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
现在我们使用into()方法传入ImageView的方法，为入口。开始源码讲解。
@Override
public Target<GlideDrawable> into(ImageView view) {
return super.into(view);
}
内部调用GenericRequestBuilder类的into方法。
public Target<TranscodeType> into(ImageView view) {
Util.assertMainThread();
if (view == null) {
throw new IllegalArgumentException("You must pass in a non null View");
}
if (!isTransformationSet && view.getScaleType() != null) {
switch (view.getScaleType()) {
case CENTER_CROP:
applyCenterCrop();
break;
case FIT_CENTER:
case FIT_START:
case FIT_END:
applyFitCenter();
break;
//$CASES-OMITTED$
default:
// Do nothing.
}
}
return into(glide.buildImageViewTarget(view, transcodeClass));
}
小结1
通过GenericRequestBuilder类的into方法。可知
<1> into()方法只能在主线程中执行。否则会抛出异常You must call this method on the main thread。
<2> Glide会默认操作ImageView的ScaleType属性，这个要注意，否则可能会出现显示问题。比如图片没有全部覆盖ImageView的情况。
<3> 最后调用本类的into(Y target)方法。也就是说传入ImageView时，最后也会生成一个Target类型的对象，然后调用into(Y target)方法。
into(Y target)方法源码
public <Y extends Target<TranscodeType>> Y into(Y target) {
Util.assertMainThread();
if (target == null) {
throw new IllegalArgumentException("You must pass in a non null Target");
}
if (!isModelSet) {
throw new IllegalArgumentException("You must first set a model (try #load())");
}
Request previous = target.getRequest();
if (previous != null) {
previous.clear();
requestTracker.removeRequest(previous);
previous.recycle();
}
Request request = buildRequest(target);
target.setRequest(request);
lifecycle.addListener(target);
requestTracker.runRequest(request);
return target;
}该方法中，代码虽然不多但是核心的代码其实是Request。Request组件其实在Glide框架中挺重要的。
首先，根据传入的target对象，获取当前target对象的Request对象，如果Request对象不为空。则清除缓存。然后重新buildRequest。
那么buildRequest()方法是如何构建Request对象的呢？
//此方法 主要获取Glide的优先级 默认NORMAL
private Request buildRequest(Target<TranscodeType> target) {
if (priority == null) {
priority = Priority.NORMAL;
}
return buildRequestRecursive(target, null);
}
//具体获取Request对象的方法
private Request buildRequestRecursive(Target<TranscodeType> target, ThumbnailRequestCoordinator parentCoordinator) {
if (thumbnailRequestBuilder != null) {
if (isThumbnailBuilt) {
throw new IllegalStateException("You cannot use a request as both the main request and a thumbnail, "
+ "consider using clone() on the request(s) passed to thumbnail()");
}
// Recursive case: contains a potentially recursive thumbnail request builder.
if (thumbnailRequestBuilder.animationFactory.equals(NoAnimation.getFactory())) {
thumbnailRequestBuilder.animationFactory = animationFactory;
}
if (thumbnailRequestBuilder.priority == null) {
thumbnailRequestBuilder.priority = getThumbnailPriority();
}
if (Util.isValidDimensions(overrideWidth, overrideHeight)
&& !Util.isValidDimensions(thumbnailRequestBuilder.overrideWidth,
thumbnailRequestBuilder.overrideHeight)) {
thumbnailRequestBuilder.override(overrideWidth, overrideHeight);
}
ThumbnailRequestCoordinator coordinator = new ThumbnailRequestCoordinator(parentCoordinator);
Request fullRequest = obtainRequest(target, sizeMultiplier, priority, coordinator);
// Guard against infinite recursion.
isThumbnailBuilt = true;
// Recursively generate thumbnail requests.
Request thumbRequest = thumbnailRequestBuilder.buildRequestRecursive(target, coordinator);
isThumbnailBuilt = false;
coordinator.setRequests(fullRequest, thumbRequest);
return coordinator;
} else if (thumbSizeMultiplier != null) {
// Base case: thumbnail multiplier generates a thumbnail request, but cannot recurse.
ThumbnailRequestCoordinator coordinator = new ThumbnailRequestCoordinator(parentCoordinator);
Request fullRequest = obtainRequest(target, sizeMultiplier, priority, coordinator);
Request thumbnailRequest = obtainRequest(target, thumbSizeMultiplier, getThumbnailPriority(), coordinator);
coordinator.setRequests(fullRequest, thumbnailRequest);
return coordinator;
} else {
// Base case: no thumbnail.
return obtainRequest(target, sizeMultiplier, priority, parentCoordinator);
}
}
private Request obtainRequest(Target<TranscodeType> target, float sizeMultiplier, Priority priority,
RequestCoordinator requestCoordinator) {
return GenericRequest.obtain(
loadProvider,
model,
signature,
context,
priority,
target,
sizeMultiplier,
placeholderDrawable,
placeholderId,
errorPlaceholder,
errorId,
fallbackDrawable,
fallbackResource,
requestListener,
requestCoordinator,
glide.getEngine(),
transformation,
transcodeClass,
isCacheable,
animationFactory,
overrideWidth,
overrideHeight,
diskCacheStrategy);
}
小结2
buildRequest()方法主要操作Glide的优先级，然后调用本类的buildRequestRecursive()方法。在buildRequestRecursive方法中核心代码是通过obtainRequest()方法来获取一个Request对象。而obtainRequest()方法中又去调用了GenericRequest的obtain()方法。注意这个obtain()方法需要传入非常多的参数，比如 placeholderId(占位图片)errorPlaceholder(出错图片)等等。
到这里我们就结束了buildRequest()方法是如何构建Request对象的问题，
下面接着into(Y target)方法继续讲解
requestTracker.runRequest(request);public void runRequest(Request request) {
requests.add(request);
if (!isPaused) {
request.begin();
} else {
pendingRequests.add(request);
}
}<1> 如果Glide处于暂停状态 则add Request 。
<2> 否则执行Request的begin()方法。
因为Request是一个接口，GenericRequest类是一个实现类。所以我们看一下GenericRequest类的begin()方法。
GenericRequest类的begin()方法源码
@Override
public void begin() {
startTime = LogTime.getLogTime();
//model等于nul(model就是我们传过来的图片路径合成的对象) 则执行onException(null);方法
if (model == null) {
onException(null);
return;
}
//如果使用override()方法设置了图片的宽高，则重写操作大小。
status = Status.WAITING_FOR_SIZE;
if (Util.isValidDimensions(overrideWidth, overrideHeight)) {
onSizeReady(overrideWidth, overrideHeight);
} else {
target.getSize(this);
}
//开始加载图片 先显示Loading的展位图
if (!isComplete() && !isFailed() && canNotifyStatusChanged()) {
target.onLoadStarted(getPlaceholderDrawable());
}
if (Log.isLoggable(TAG, Log.VERBOSE)) {
logV("finished run method in " + LogTime.getElapsedMillis(startTime));
}
}
@Override
public void onException(Exception e) {
if (Log.isLoggable(TAG, Log.DEBUG)) {
Log.d(TAG, "load failed", e);
}
status = Status.FAILED;
//TODO: what if this is a thumbnail request?
if (requestListener == null || !requestListener.onException(e, model, target, isFirstReadyResource())) {
setErrorPlaceholder(e);
}
}也就是，如果图片路径为空，则先显示错误的图片占位，如果没有设置，再显示加载中的图片占位。
onSizeReady方法源码
@Override
public void onSizeReady(int width, int height) {
if (Log.isLoggable(TAG, Log.VERBOSE)) {
logV("Got onSizeReady in " + LogTime.getElapsedMillis(startTime));
}
if (status != Status.WAITING_FOR_SIZE) {
return;
}
status = Status.RUNNING;
width = Math.round(sizeMultiplier * width);
height = Math.round(sizeMultiplier * height);
ModelLoader<A, T> modelLoader = loadProvider.getModelLoader();
final DataFetcher<T> dataFetcher = modelLoader.getResourceFetcher(model, width, height);
if (dataFetcher == null) {
onException(new Exception("Failed to load model: '" + model + "'"));
return;
}
ResourceTranscoder<Z, R> transcoder = loadProvider.getTranscoder();
if (Log.isLoggable(TAG, Log.VERBOSE)) {
logV("finished setup for calling load in " + LogTime.getElapsedMillis(startTime));
}
loadedFromMemoryCache = true;
loadStatus = engine.load(signature, width, height, dataFetcher, loadProvider, transformation, transcoder,
priority, isMemoryCacheable, diskCacheStrategy, this);
loadedFromMemoryCache = resource != null;
if (Log.isLoggable(TAG, Log.VERBOSE)) {
logV("finished onSizeReady in " + LogTime.getElapsedMillis(startTime));
}
}
核心代码
private Engine engine;
loadStatus = engine.load(signature, width, height, dataFetcher, loadProvider, transformation, transcoder,priority, isMemoryCacheable, diskCacheStrategy, this);也就是调用Engine类的load方法。
public <T, Z, R> LoadStatus load(Key signature, int width, int height, DataFetcher<T> fetcher,
DataLoadProvider<T, Z> loadProvider, Transformation<Z> transformation, ResourceTranscoder<Z, R> transcoder,
Priority priority, boolean isMemoryCacheable, DiskCacheStrategy diskCacheStrategy, ResourceCallback cb) {
EngineRunnable runnable = new EngineRunnable(engineJob, decodeJob, priority);
}
然后 从Engine类的load方法到EngineRunnable类的run方法
@Override
public void run() {
if (isCancelled) {
return;
}
Exception exception = null;
Resource<?> resource = null;
try {
resource = decode();
} catch (Exception e) {
if (Log.isLoggable(TAG, Log.VERBOSE)) {
Log.v(TAG, "Exception decoding", e);
}
exception = e;
}
if (isCancelled) {
if (resource != null) {
resource.recycle();
}
return;
}
if (resource == null) {
onLoadFailed(exception);
} else {
onLoadComplete(resource);
}
}
然后到EngineRunnable类的decode()方法
private Resource<?> decode() throws Exception {
if (isDecodingFromCache()) {
return decodeFromCache();
} else {
return decodeFromSource();
}
}这可以看出 有两个方法，一个是取缓存中的数据，一个是取数据。取缓存的方法下一章节讲解，现在看取数据的decodeFromSource();方法
private Resource<?> decodeFromSource() throws Exception {
return decodeJob.decodeFromSource();
}
然后从EngineRunnable类的decodeFromSource()方法再到DecodeJob类的decodeFromSource()方法。
public Resource<Z> decodeFromSource() throws Exception {
Resource<T> decoded = decodeSource();
return transformEncodeAndTranscode(decoded);
}
然后DecodeJob类的decodeFromSource()方法到DecodeJob类的decodeSource()方法。
private Resource<T> decodeSource() throws Exception {
Resource<T> decoded = null;
try {
long startTime = LogTime.getLogTime();
final A data = fetcher.loadData(priority);
if (Log.isLoggable(TAG, Log.VERBOSE)) {
logWithTimeAndKey("Fetched data", startTime);
}
if (isCancelled) {
return null;
}
decoded = decodeFromSourceData(data);
} finally {
fetcher.cleanup();
}
return decoded;
}核心代码
final A data = fetcher.loadData(priority);到ImageVideoModelLoader类的loadData方法。
@Override
public ImageVideoWrapper loadData(Priority priority) throws Exception {
InputStream is = null;
if (streamFetcher != null) {
try {
is = streamFetcher.loadData(priority);
} catch (Exception e) {
if (Log.isLoggable(TAG, Log.VERBOSE)) {
Log.v(TAG, "Exception fetching input stream, trying ParcelFileDescriptor", e);
}
if (fileDescriptorFetcher == null) {
throw e;
}
}
}
ParcelFileDescriptor fileDescriptor = null;
if (fileDescriptorFetcher != null) {
try {
fileDescriptor = fileDescriptorFetcher.loadData(priority);
} catch (Exception e) {
if (Log.isLoggable(TAG, Log.VERBOSE)) {
Log.v(TAG, "Exception fetching ParcelFileDescriptor", e);
}
if (is == null) {
throw e;
}
}
}
return new ImageVideoWrapper(is, fileDescriptor);
}核心代码
is = streamFetcher.loadData(priority);
到HttpUrlFetcher类的loadData()方法
private HttpURLConnection urlConnection;
private InputStream stream;
@Override
public InputStream loadData(Priority priority) throws Exception {
return loadDataWithRedirects(glideUrl.toURL(), 0 /*redirects*/, null /*lastUrl*/, glideUrl.getHeaders());
}
private InputStream loadDataWithRedirects(URL url, int redirects, URL lastUrl, Map<String, String> headers)
throws IOException {
if (redirects >= MAXIMUM_REDIRECTS) {
throw new IOException("Too many (> " + MAXIMUM_REDIRECTS + ") redirects!");
} else {
// Comparing the URLs using .equals performs additional network I/O and is generally broken.
// See http://michaelscharf.blogspot.com/2006/11/javaneturlequals-and-hashcode-make.html.
try {
if (lastUrl != null && url.toURI().equals(lastUrl.toURI())) {
throw new IOException("In re-direct loop");
}
} catch (URISyntaxException e) {
// Do nothing, this is best effort.
}
}
urlConnection = connectionFactory.build(url);
for (Map.Entry<String, String> headerEntry : headers.entrySet()) {
urlConnection.addRequestProperty(headerEntry.getKey(), headerEntry.getValue());
}
urlConnection.setConnectTimeout(2500);
urlConnection.setReadTimeout(2500);
urlConnection.setUseCaches(false);
urlConnection.setDoInput(true);
// Connect explicitly to avoid errors in decoders if connection fails.
urlConnection.connect();
if (isCancelled) {
return null;
}
final int statusCode = urlConnection.getResponseCode();
if (statusCode / 100 == 2) {
return getStreamForSuccessfulRequest(urlConnection);
} else if (statusCode / 100 == 3) {
String redirectUrlString = urlConnection.getHeaderField("Location");
if (TextUtils.isEmpty(redirectUrlString)) {
throw new IOException("Received empty or null redirect url");
}
URL redirectUrl = new URL(url, redirectUrlString);
return loadDataWithRedirects(redirectUrl, redirects + 1, url, headers);
} else {
if (statusCode == -1) {
throw new IOException("Unable to retrieve response code from HttpUrlConnection.");
}
throw new IOException("Request failed " + statusCode + ": " + urlConnection.getResponseMessage());
}
}到这里其实就告一段落了，因为已经通过HttpURLConnection获取到了图片流了，剩余的就是将图片流转换成Bitmap了。
总结
1.Glide框架的with方法返回RequestManager对象。可以在子线程操作，也可以在主线程操作。可以传入Context对象，也可以传入Activity对象或者Fragment对象。在线程操作时，无论with()方法参数传入什么都使用Application对象返回RequestManager对象。Glide的生命周期和Application一样。主线程中操作时，根据with()方法参数决定Glide的生命周期，比如传入Activity，那么Glide的生命周期就是Activity的生命周期，传入Application，那么Glide的生命周期就是Application的生命周期。
2.Glide框架的load方法返回DrawableTypeRequest对象，有多个重载方法。可以加载不同类型的图片，比如网络图片，比如本地图片，比如File图片。
3.Glide框架的into方法返回Target对象。内部源码众多，有多个重载方法。一个传入ImageView对象，一个传入Target对象。内部都是转换成Target对象。大体的流程是。
首先获取Request对象。经过一系列的操作到ImageVideoModelLoader类的loadData方法。最后到HttpUrlFetcher类的loadData方法。然后在该类中通过HttpURLConnection对象获取InputStream对象。最终转换成Bitmap对象。显示在View上。
最后
以上就是深情水壶为你收集整理的Glide源码详解(基于3.X版本)的全部内容，希望文章能够帮你解决Glide源码详解(基于3.X版本)所遇到的程序开发问题。
如果觉得靠谱客网站的内容还不错，欢迎将靠谱客网站推荐给程序员好友。
发表评论 取消回复