1. 静态 Activity
2. 静态 View
3. 非静态内部类
4. 匿名类
5. Handler
6. Thread
7. TimerTask
8. SensorManager
1.资源对象没关闭造成的内存泄漏
2.构造Adapter时，没有使用缓存的convertView
3.Bitmap对象不在使用时调用recycle()释放内存
4.试着使用关于application的context来替代和activity相关的context
5.注册没取消造成的内存泄漏
6.集合中对象没清理造成的内存泄漏
避免引用Context造成的内存泄露
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
interface 放在fragment内或者放在外面单独存在，一般不会造成activity泄漏
public interface DialogCallback {
void showModifyInputDialog();
void showTheMessageDialog();
}
其实一般的匿名内部类是不会导致activity释放不了的，只要你不在handle内进行奇怪的操作
private Handler uiHandler = new Handler(){
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
最近在维护代码，发现一个自定义View（这个View是在一个AsyncTask的工作线程doInBackground中新建的，在UI线程onPostExecute中添加进window中的）经常会泄漏内存，导致其引用的Activity一直得不到释放，每次退出再进去都会导致Activity的对象+1.
package com.xxx.launcher.view;
import android.content.Context;
import android.util.Log;
import android.view.View;
public class WeatherTextView extends SkinTextView {
public WeatherTextView (Context context) {
super(context); postDelayed(mShowCityRunnable, 200);//这一步有问题
}
@Override
protected void onWindowVisibilityChanged(int visibility) {
super.onWindowVisibilityChanged(visibility);
if (visibility == View.VISIBLE) {
post(mShowCityRunnable);
}
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
onCancel();
};
public void onCancel(){
removeCallbacks(mShowCityRunnable);
}
private Runnable mShowCityRunnable = new Runnable() {
@Override
public void run() {
Log.i("mShowCityRunnable-------TAG", "run"+mShowCityRunnable);
setText(city);
}
};
}
最后通过MAT工具查看内存快照的比较，发现了如下的情况，把内存泄露的地方锁定在了WeatherTextView$2的第二个内部类中mShowCityRunnable ，一开始始终都想不到这个内部类到底有什么地方泄露了，最后突然灵光一闪，是不是View的post（）方法导致的，在网上一查，发现确实。
public boolean post(Runnable action) {
Handler handler;
AttachInfo attachInfo = mAttachInfo;
if (attachInfo != null) {
handler = attachInfo.mHandler;
} else {
// Assume that post will succeed later
ViewRootImpl.getRunQueue().post(action);
return true;
}
return handler.post(action);
}
在post() 函数注释中，明确写着：This method can be invoked from outside of the UI thread only when this View is attached to a window.
当View还没有attach到当前window时，mAttachInfo 值为 null，故而执行 else语句，再看一下getRunQueue()和其post() 方法：
static final ThreadLocal<RunQueue> sRunQueues = new ThreadLocal<RunQueue>();
static RunQueue getRunQueue() {
RunQueue rq = sRunQueues.get();
if (rq != null) {
return rq;
}
rq = new RunQueue();
sRunQueues.set(rq);
return rq;
}
……
static final class RunQueue {
private final ArrayList<HandlerAction> mActions = new ArrayList<HandlerAction>();
void post(Runnable action) {
postDelayed(action, 0);
}
void postDelayed(Runnable action, long delayMillis) {
HandlerAction handlerAction = new HandlerAction();
handlerAction.action = action;
handlerAction.delay = delayMillis;
synchronized (mActions) {
mActions.add(handlerAction);
}
}
void executeActions(Handler handler) {
synchronized (mActions) {
final ArrayList<handleraction> actions = mActions;
final int count = actions.size();
for (int i = 0; i < count; i++) {
final HandlerAction handlerAction = actions.get(i);
handler.postDelayed(handlerAction.action, handlerAction.delay);
}
actions.clear();
}
}
……
}
这样会把Runnable 插入到一个静态的ThreadLocal的RunQueue队列里（在工作线程中post，就会插入工作线程的RunQueue队列），针对本文开头给出的例子，那么插入的Runnable什么时候得到执行呢?
调用RunQueue.executeActions()方法只有一处，即在ViewRootImpl类的如下非静态方法中
private void performTraversals() {
if (mLayoutRequested && !mStopped) {
// Execute enqueued actions on every layout in case a view that was detached
// enqueued an action after being detached
getRunQueue().executeActions(attachInfo.mHandler);
}
}
该方法是在UI线程执行的（见ViewRootImpl.handleMessage()）， 故当UI线程执行到该performTraversals() 里的 getRunQueue() 时，得到的是UI线程中的RunQueue，这样AsyncTask 线程中的 RunQueue永远不会被执行到， 并且AsyncTask的是用线程池实现的，AsyncTask启动的线程会长期存在，造成如下引用关系：
AsyncTask线程 => 静态的ThreadLocal的RunQueue => Runnable => View=> Activity；
如此即使activity finish 了，确始终存在一个静态引用链引用这该activity，而 Activity一般又引用着很多资源，比如图片等，最终造成严重资源泄漏。
最后我是写改成
package com.xxx.launcher.view;
import android.content.Context;
import android.util.Log;
import android.view.View;
public class WeatherTextView extends SkinTextView {
public WeatherTextView (Context context) {
super(context);
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
postDelayed(mShowCityRunnable, 200); //在onAttachedToWindow方法中执行post方法
}
@Override
protected void onWindowVisibilityChanged(int visibility) {
super.onWindowVisibilityChanged(visibility);
if (visibility == View.VISIBLE) {
post(mShowCityRunnable);
}
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
onCancel();
};
public void onCancel(){
removeCallbacks(mShowCityRunnable);
}
private Runnable mShowCityRunnable = new Runnable() {
@Override
public void run() {
Log.i("mShowCityRunnable-------TAG", "run"+mShowCityRunnable);
setText(city);
}
};
}
这样Activity就没有再被其他东西引用了，就不会发生Activity的泄漏了，Activity就可以被释放了。这样，不管进入退出进入这个MainMenuActivity多少次，MainMenuActivity的对象就只会保存一份。
ps：至于为什么在两个Histogram（直方图）的比较图中还是显示MainMenuActivity+1，则是因为这是类名，类被加载之后，在进程结束之前不会被回收
===============================================================================================================================
===============================================================================================================================
这种泄漏一般是因为mStorageManager 注册了但是没有取消注册
mStorageManager = (StorageManager) mContext.getSystemService(Context.STORAGE_SERVICE);
mStorageManager.registerListener(mStoragelistener);
取消注册就可以了
if (mStorageManager != null) {
mStorageManager.unregisterListener(mStoragelistener);
}