android–这个Handler类应该是静态的,否则可能会发生泄漏(com.test.test3.ui.MainActivity.1)

我是android的新手,我尝试开发一个系统但是当我完成代码时,处理程序会显示此警告

下面显示我编辑后的代码,事件ontounch中的处理程序显示警告处理程序无法解析.我尝试将//忽略处理程序,我尝试运行应用程序并将其结果强制关闭.

public class MainActivity extends Activity {
protected static final int STOP = 100;
ImageView iv;
private ProgressBar pb;
LinearLayout ll;
private AnimationDrawable anim;
ScrollView sv;
private SQLiteDatabase db;
private boolean flagscanning = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ll = new LinearLayout(this);
new HandlerClass(this);
db = SQLiteDatabase.openDatabase(Environment.getExternalStorageDirectory()+"/antivirus.sqlite", null, SQLiteDatabase.OPEN_READONLY);
iv = (ImageView) this.findViewById(R.id.imageView1);
//扫描病毒进度条
pb = (ProgressBar) this.findViewById(R.id.progressBar1);
ll = (LinearLayout) this.findViewById(R.id.ll);
//设置ImageView背景资源为动画文件
iv.setBackgroundResource(R.drawable.bg);
//sv用来显示病毒的扫描结果
sv = (ScrollView) this.findViewById(R.id.scrollView1);
anim = (AnimationDrawable) iv.getBackground();
}
private static class HandlerClass extends Handler{
private final WeakReference mTarget;
public HandlerClass(MainActivity context){
mTarget = new WeakReference((MainActivity) context);
}
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
MainActivity target = mTarget.get();
if(msg.what==STOP){
target.ll.removeAllViews();
//anim.stop();
}
String str = (String) msg.obj;
TextView tv = new TextView(target);
tv.setText(str);
target.ll.setOrientation(LinearLayout.VERTICAL);
target.ll.addView(tv);
//sv.scrollBy(0, 20);
System.out.println(str);
}
};
@Override
public boolean onTouchEvent(MotionEvent event) {
//如果程序正在杀毒过程中,拒绝再次启动杀毒线程
if(flagscanning){
return false;
}
//如果用户触摸屏幕,则开启杀毒线程
if (event.getAction() == MotionEvent.ACTION_UP) {
flagscanning= true;
anim.start();
new Thread() {
public void run() {
// 获取每一个应用程序的签名,签名须与数据库的签名想比较
List

infos = getPackageManager()
.getInstalledPackages(PackageManager.GET_UNINSTALLED_PACKAGES | PackageManager.GET_SIGNATURES);
//设置进度条的扫描范围
pb.setMax(infos.size());
int total = 0;
int virustotal = 0;//设置初始病毒数为0
for (PackageInfo info : infos) {
total++;
try {
sleep(20);//只为便于观察扫描效果和进度,无实质作用
} catch (InterruptedException e) {
e.printStackTrace();
}
Message msg = Message.obtain();
msg.obj = "正在扫描" + info.packageName;
_handler.sendMessage(msg);_
Signature[] signs = info.signatures;
String str = signs[0].toCharsString();
String md5 = MD5Encoder.encode(str);
//将应用程序签名与数据库中保存的签名进行比较,如果相一致,则使病毒数加1,并通过handler在界面显示病毒包名
Cursor cursor = db.rawQuery("select desc from datable where md5=?",new String[] { md5 });
if (cursor.moveToFirst()) {
String desc = cursor.getString(0);
msg = Message.obtain();
msg.obj = info.packageName + ": " + desc;
_handler.sendMessage(msg);_
virustotal++;
}
cursor.close();
pb.setProgress(total);
}
Message msg = Message.obtain();
msg.what = STOP;
msg.obj = "扫描完毕 ,共发现" + virustotal + "个病毒";
_handler.sendMessage(msg);_
flagscanning = false;
pb.setProgress(0);
};
}.start();
}
return super.onTouchEvent(event);
}
@Override
protected void onDestroy() {
if (db.isOpen())
db.close();
super.onDestroy();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}


解决方法:

使您的处理程序成为静态类.

警告是一个棉绒警告.您可以禁用警告,但它是一个有用的信息

这是一个Lint Check列表

http://tools.android.com/tips/lint-checks

引自来源@

http://android-developers.blogspot.in/2009/01/avoiding-memory-leaks.html

如果不控制生命周期,请避免活动中的非静态内部类,使用静态内部类并对内部活动进行弱引用.

这个问题的解决方案是使用带有WeakReference的静态内部类到外部类,例如在ViewRoot及其W内部类中完成.

另请查看android开发者小组的讨论.检查Romain Guy的解决方案

https://groups.google.com/forum/#!topic/android-developers/1aPZXZG6kWk

来自上述链接的Romain Guy解决方案的示例

class OuterClass {
class InnerClass {
private final WeakReference mTarget;
InnerClass(OuterClass target) {
mTarget = new WeakReference(target);
}
void doSomething() {
OuterClass target = mTarget.get();
if (target != null) target.do();
}


编辑：

例：

public class MainActivity extends Activity {
LinearLayout ll;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ll = new LinearLayout(this);
new HandlerClass(this);
}
private static class HandlerClass extends Handler{
private final WeakReference mTarget;
public HandlerClass(MainActivity context)
{
mTarget = new WeakReference((MainActivity) context);
}
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
MainActivity target = mTarget.get();
if (target != null)
if(msg.what==1){
target.ll.removeAllViews();
// anim.stop();
}
String str = (String) msg.obj;
TextView tv = new TextView(target);
tv.setText(str);
target.ll.setOrientation(LinearLayout.VERTICAL);
target.ll.addView(tv);
//sv.scrollBy(0, 20);
System.out.println(str);
}
};
}


如果上述错误或有问题,请纠正我.

您还可以通过Alex Lockwood查看此博客

http://www.androiddesignpatterns.com/2013/01/inner-class-handler-memory-leak.html