public interface DownloadListener {
public void onDownloaded();
}
public class DownloadManager {
private static DownloadManager instance;
private DownloadListener mDownloadListener;
public static synchronized DownloadManager getInstance(){
if(instance == null)
instance = new DownloadManager();
return instance;
}
private DownloadManager() {
myHandler.sendEmptyMessageDelayed(29, 3 * 1000);
}
public void registerDownloadListener(DownloadListener downloadListener) {
mDownloadListener = downloadListener;
}
Handler myHandler = new Handler(new Handler.Callback() {
@Override
public boolean handleMessage(Message msg) {
if (msg.what == 29) {
mDownloadListener.onDownloaded();
return true;
}
return false;
}
});
}
public class I implements DownloadListener {
public I() {
DownloadManager.getInstance().registerDownloadListener(this);
}
@Override
public void onDownloaded() {
Log.e("TAG", "I onDownloaded");
}
}
public class You implements DownloadListener {
public You() {
DownloadManager.getInstance().registerDownloadListener(this);
}
@Override
public void onDownloaded() {
Log.e("TAG", "You onDownloaded");
}
}
public class PATTERNSActivity extends Activity implements DownloadListener {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
new I();
new You();
DownloadManager.getInstance().registerDownloadListener(this);
}
@Override
public void onDownloaded() {
Log.e("TAG","PATTERNSActivity onDownloaded");
}
}
我期望得到:
I onDownloaded
You onDownloaded
PATTERNSActivity onDownloaded
但我只得到:
PATTERNSActivity onDownloaded
这可能是什么问题?
最佳答案
您将注册的下载器保存在单个实例属性中:
// Last call's downloadListener wins.
public void registerDownloadListener(DownloadListener downloadListener) {
mDownloadListener = downloadListener;
}
最后注册的是该 Activity 的:
new I(); // First set singleton's property to an instance of I...
new You(); // ...then to an instance of You...
// ...then to the current instance.
DownloadManager.getInstance().registerDownloadListener(this);
<小时/>
根据您的评论进行编辑。
public void registerDownloadListener(DownloadListener downloadListener) {
mDownloadListeners.add(downloadListener);
}
...
public boolean handleMessage(Message msg) {
if (msg.what != 29) {
return false;
}
for (DownloadListener listener : mDownloadListeners) {
listener.onDownloaded();
}
return true;
}
关于java - 为什么我的所有听众都没有注册?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/8732759/