Handler内存泄漏的处理方法
过去 Android 使用 Handler 进行线程间通信来更新 UI ，但在 Android Studio 2.3.3 之后使用传统的写法 IDE 会提示：
”This Handler class should be static or leaks might occur.“
传统写法如下：
public class MainActivity extends Activity {
private final Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
// TODO
}
}
}
Android Framework 的工程师 Romain Guy 在 Google 论坛上做出过解释：
I wrote that debugging code because of a couple of memory leaks I
found in the Android codebase. Like you said, a Message has a
reference to the Handler which, when it's inner and non-static, has a
reference to the outer this (an Activity for instance.) If the Message
lives in the queue for a long time, which happens fairly easily when
posting a delayed message for instance, you keep a reference to the
Activity and "leak" all the views and resources. It gets even worse
when you obtain a Message and don't post it right away but keep it
somewhere (for instance in a static structure) for later use.
并且给出了他的建议写法：
class OuterClass {
class InnerClass {
private final WeakReference<OuterClass> mTarget;
InnerClass(OuterClass target) {
mTarget = new WeakReference<OuterClass>(target);
}
void doSomething() {
OuterClass target = mTarget.get();
if (target != null) {
target.do();
}
}
}