引用
implementation 'com.github.bumptech.glide:glide:4.9.0'
annotationProcessor 'com.github.bumptech.glide:compiler:4.9.0'
使用
Glide.with(GlideActivity.this)
.load(url)
.centerCrop()
.placeholder(R.mipmap.ic_launcher)
.error(R.mipmap.ic_launcher)
.transform(new GlideCircleTransform(CommonStaffSelectedForRoleActivity.this))
.into(imageView);
优点
-
Glide可以监听Activity的生命周期管理，更加合理的管理图片的加载和释放。
-
Glide可以加载Gif图。
-
缓存策略和加载速度。Picasso缓存的是全尺寸，而Glide的缓存的图片和ImageView的尺寸相同。Glide的这个特点,让加载显得特别的快,而Picasso则因为需要在显示之前重新调整大小而导致一些延迟。
-
Glide可以通过自定义GlideMoudle来完成特殊的加载需求，例如加载加密的图片等
源码分析
源码太多，只能根据一条主线走下去，也就是Glide三个重要方法，with,load,into。
with
那么glide是怎样通过with传入的参数。如何绑定生命周期？如何传递生命周期？
首先从glide的静态方法with分析。
@NonNull
public static RequestManager with(@NonNull View view) {
return getRetriever(view.getContext()).get(view);
}
@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.getActivity()).get(fragment);
}
@SuppressWarnings("deprecation")
@Deprecated
@NonNull
public static RequestManager with(@NonNull android.app.Fragment fragment) {
return getRetriever(fragment.getActivity()).get(fragment);
}
……
参数可以是with的参数可以是android.app.Activity、android.app.Fragment、android.support.v4.app.Fragment、android.support.v4.app.FragmentActivity等。
@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();
}
内部都是通过getRetriever方法获取RequestManagerRetriever对象再调用get方法。
@NonNull
public RequestManager get(@NonNull FragmentActivity activity) {
if (Util.isOnBackgroundThread()) {
return get(activity.getApplicationContext());
} else {
assertNotDestroyed(activity);
FragmentManager fm = activity.getSupportFragmentManager();
return supportFragmentGet(
activity, fm, /*parentHint=*/ null, isActivityVisible(activity));
}
}
@NonNull
public RequestManager get(@NonNull Fragment fragment) {
Preconditions.checkNotNull(fragment.getActivity(),
"You cannot start a load on a fragment before it is attached or after it is destroyed");
if (Util.isOnBackgroundThread()) {
return get(fragment.getActivity().getApplicationContext());
} else {
FragmentManager fm = fragment.getChildFragmentManager();
return supportFragmentGet(fragment.getActivity(), fm, fragment, fragment.isVisible());
}
}
@SuppressWarnings("deprecation")
@NonNull
public RequestManager get(@NonNull Activity activity) {
if (Util.isOnBackgroundThread()) {
return get(activity.getApplicationContext());
} else {
assertNotDestroyed(activity);
android.app.FragmentManager fm = activity.getFragmentManager();
return fragmentGet(
activity, fm, /*parentHint=*/ null, isActivityVisible(activity));
}
}
……
通过get方法内部可以看出，通过将fm作为参数最后调用supportFragmentGet 或者fragmentGet返回一个RequestManager对象。那么这个RequestManager对象是干嘛的呢？接着下面看。
@NonNull
private RequestManager supportFragmentGet(
@NonNull Context context,
@NonNull FragmentManager fm,
@Nullable Fragment parentHint,
boolean isParentVisible) {
SupportRequestManagerFragment current =
getSupportRequestManagerFragment(fm, parentHint, isParentVisible);
RequestManager requestManager = current.getRequestManager();
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;
}
原来RequestManager是通过current（RequestManagerFragment）对setRequestManager设置的。首先看下getSupportRequestManagerFragment是怎么获取的RequestManagerFragment对象。
@NonNull
private SupportRequestManagerFragment getSupportRequestManagerFragment(
@NonNull final FragmentManager fm, @Nullable Fragment parentHint, boolean isParentVisible) {
SupportRequestManagerFragment current =
(SupportRequestManagerFragment) fm.findFragmentByTag(FRAGMENT_TAG);
if (current == null) {
current = pendingSupportRequestManagerFragments.get(fm);
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;
}
SupportRequestManagerFragment初始化的时候，需要创建一个ActivityFragmentLifecycle，初始化成员变量lifecycle。
public SupportRequestManagerFragment() {
this(new ActivityFragmentLifecycle());
}
@VisibleForTesting
@SuppressLint("ValidFragment")
public SupportRequestManagerFragment(@NonNull ActivityFragmentLifecycle lifecycle) {
this.lifecycle = lifecycle;
}
然后看到了下面这句
fm.beginTransaction().add(current, FRAGMENT_TAG).commitAllowingStateLoss();
原来通过当前activity的fm管理器添加将空页面的SupportRequestManagerFragment的fragment添加进去，并返回这个空页面的fragment。
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);
}
再来看通过current.getLifecycle()获取fragment的lifecycle，传入requestManager，将fragment和requestManager建立联系。
load
load方法主要是加载网络地址，图片资源，可以是本地图片、应用资源、二进制流、uri对象。
into
缓存相关
Glide资源加载流程，内存缓存加载
内存缓存分为两部分，弱引用持有的活动缓存和LruCache管理的非活动缓存。
什么叫活动缓存，就是该图片有被用来显示就是活动的，如果没有被显示，就是非活动的。
因此活动的图片缓存没有必要放入LruCache管理，因为此时它不应该被回收，而如果该图片不再被显示了，也就是release为0了之后，就会重新放入非活动缓存中由LruCache管理它的缓存，因此LruCache管理的内存缓存大小并不包含正在显示的图片
Glide磁盘缓存资源加载
- **ALL: **缓存原始数据和转换后的数据
- **NONE: **不缓存
- **DATA: **原始数据，未经过解码或者转换
- **RESOURCE: **缓存经过解码的数据
- **AUTOMATIC(默认)：**根据
EncodeStrategy和DataSource等条件自动选择合适的缓存方