Java的不能内螺纹创建处理程序，并没有所谓的活套。prepare（） [英] Java Can't create handler inside thread that has not called Looper.prepare()
问题描述
我看到大部分的相关问题，但我找不到任何固定我的问题。
I saw most of the related questions, but I couldn't find any that fixed my problem.
这是我的code，我不知道我做错了。
This is my code, and I have no idea what I'm doing wrong.
static class NamedFile {
public File f;
public String name;
public String ext;
public String path;
public BitmapDrawable icon;
public NamedFile (File file) {
f = file;
name = f.getName();
if (f.isFile()) {
if (name.indexOf('.') != -1) {
ext = name.substring(name.lastIndexOf('.') + 1).trim().toLowerCase();
} else {
ext = "unknown";
}
}
path = f.getAbsolutePath();
if (ext == null) {
icon = mFolderIcon;
} else {
BitmapDrawable i = icons.get(ext);
if (i == null) {
try {
int rid = R.drawable.class.getField(ext).getInt(R.drawable.class);
icons.put(ext, new BitmapDrawable(Bitmap.createScaledBitmap(BitmapFactory.decodeResource(res, rid, mOpts), iconSize, iconSize, false)));
icon = icons.get(ext);
} catch (Exception e1) {}
} else {
icon = i;
}
}/* else if (ext.equals("jpeg") || ext.equals("jpg") || ext.equals("bmp") || ext.equals("gif") || ext.equals("png")) {
Bitmap b = BitmapFactory.decodeFile(path, mOpts);
if (b != null) {
icon = new BitmapDrawable(Bitmap.createScaledBitmap(b, iconSize, iconSize, false));
}
}*/
if (ext != null && (ext.equals("jpeg") || ext.equals("jpg") || ext.equals("bmp") || ext.equals("gif") || ext.equals("png"))) {
/*
Bitmap b = BitmapFactory.decodeFile(path, mOpts);
if (b != null) {
icon = new BitmapDrawable(Bitmap.createScaledBitmap(b, iconSize, iconSize, false));
}
*/
final Handler handler = new Handler() {
@Override
public void handleMessage(Message message) {
HashMap<String, Object> m = ((HashMap<String, Object>)message.obj);
sendThumbnail ((String)m.get("path"), (byte[])m.get("data"));
}
};
Thread thread = new Thread() {
public void writeInt (byte[] buff, int pos, int value) {
buff[pos] = (byte)(value >>> 24);
buff[pos + 1] = (byte)(value >>> 16);
buff[pos + 2] = (byte)(value >>> 8);
buff[pos + 3] = (byte)value;
}
@Override
public void run() {
try {
Bitmap b = BitmapFactory.decodeFile(path, mOpts);
if (b.getHeight() > 256 || b.getWidth() > 256) {
float r;
if (b.getHeight() > b.getWidth()) {
r = 128f / b.getHeight();
} else {
r = 128f / b.getWidth();
}
b = Bitmap.createScaledBitmap(b, (int)(r * b.getWidth()), (int)(r * b.getHeight()), false);
byte[] buffer = new byte[b.getWidth() * b.getHeight() * 4 + 8];
writeInt (buffer, 0, b.getWidth());
writeInt (buffer, 4, b.getHeight());
int i = 8;
for (int y = 0; y < b.getHeight(); y ++) {
for (int x = 0; x < b.getWidth(); x ++) {
writeInt (buffer, i, b.getPixel(x, y));
i += 4;
}
}
HashMap<String, Object> msg = new HashMap<String, Object>();
msg.put("path", path);
msg.put("data", buffer);
Message message = handler.obtainMessage(1, msg);
handler.sendMessage(message);
}
} catch (Exception e) {
sendLog (e.toString());
}
}
};
thread.start();
}
if (icon == null) {
icon = mFileIcon;
}
}
public NamedFile () {
}
public NamedFile simpleClone () {
final NamedFile nf = new NamedFile();
nf.name = name;
nf.ext = ext;
nf.path = path;
return nf;
}
}
嵌套if语句是在静态类的构造函数和静态类是在扩展ListActivity一个公共类这里面。我是新来的Java。
This is nested inside an if statement that is in a static class' constructor function and the static class is in a public class that extends ListActivity. I'm new to Java.
错误：
05-01 20:21:58.810: E/AndroidRuntime(584): Uncaught handler: thread AsyncTask #1 exiting due to uncaught exception
05-01 20:21:58.830: E/AndroidRuntime(584): java.lang.RuntimeException: An error occured while executing doInBackground()
05-01 20:21:58.830: E/AndroidRuntime(584): at android.os.AsyncTask$3.done(AsyncTask.java:200)
05-01 20:21:58.830: E/AndroidRuntime(584): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
05-01 20:21:58.830: E/AndroidRuntime(584): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
05-01 20:21:58.830: E/AndroidRuntime(584): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
05-01 20:21:58.830: E/AndroidRuntime(584): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
05-01 20:21:58.830: E/AndroidRuntime(584): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
05-01 20:21:58.830: E/AndroidRuntime(584): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
05-01 20:21:58.830: E/AndroidRuntime(584): at java.lang.Thread.run(Thread.java:1096)
05-01 20:21:58.830: E/AndroidRuntime(584): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
05-01 20:21:58.830: E/AndroidRuntime(584): at android.os.Handler.<init>(Handler.java:121)
05-01 20:21:58.830: E/AndroidRuntime(584): at greg.projects.FileTransfer.FileTransferActivity$NamedFile$1.<init>(FileTransferActivity.java:588)
05-01 20:21:58.830: E/AndroidRuntime(584): at greg.projects.FileTransfer.FileTransferActivity$NamedFile.<init>(FileTransferActivity.java:588)
05-01 20:21:58.830: E/AndroidRuntime(584): at greg.projects.FileTransfer.FileTransferActivity$GesturesLoadTask.doInBackground(FileTransferActivity.java:489)
05-01 20:21:58.830: E/AndroidRuntime(584): at greg.projects.FileTransfer.FileTransferActivity$GesturesLoadTask.doInBackground(FileTransferActivity.java:1)
05-01 20:21:58.830: E/AndroidRuntime(584): at android.os.AsyncTask$2.call(AsyncTask.java:185)
05-01 20:21:58.830: E/AndroidRuntime(584): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
05-01 20:21:58.830: E/AndroidRuntime(584): ... 4 more
（FileTransferActivity.java:588是最后的处理程序处理程序=新的处理程序（）{）
推荐答案
A 处理程序基本上是Android使用异步运行code，当你发送一个回调类某种形式的它的消息。为了让处理程序来接收和从UI线程独立的线程处理消息，它必须保持线程开放。这就是在活套类的原因。就像在页面的例子，调用活套。prepare（）在运行的顶部（）的方法，然后调用 Looper.loop（）在底部。该线将继续开放，直到你明确地摧毁它。为了摧毁一个尺蠖线程，你必须在你的发类调用
A Handler is basically a callback class that Android uses to asynchronously run code when you send it messages of some form. In order for a Handler to receive and handle messages in a separate thread from the UI thread, it must keep the thread open. That is where the Looper class comes in. Like in the example of the page, call Looper.prepare() at the top of the run() method, then call Looper.loop() at the bottom. The thread will stay open until you explicitly destroy it. In order to destroy a Looper thread, you must have a method in your Thread class that calls Looper.getMyLooper().quit().
这是例子线程类将是这样的：
An example thread class would be something like this:
class LooperThread extends Thread {
public Handler mHandler;
private volatile Looper mMyLooper;
public void run() {
Looper.prepare();
mHandler = new Handler() {
public void handleMessage(Message msg) {
// process incoming messages here
}
};
mMyLooper = Looper.getMyLooper();
Looper.loop();
}
public void killMe(){
mMyLooper.quit();
}
}
通过创建一个新的对象运行的线程正常。
Run the thread normally by creating a new object of it.
LooperThread myLooperThread = new LooperThread();
保持对它的引用。然后调用：
Hold a reference to it. Then call:
myLooperThread.killMe();
每当你想的线程死亡。这通常是在的onPause（），的onStop（）或的onDestroy（）方法的活动的。
Whenever you want the thread to die. This is usually in the onPause(), onStop(), or onDestroy() methods of the Activity.
请注意，这种性质的螺纹将继续开放，当活动被关闭，所以你必须杀死它在用户退出之前
Please note that a thread of this nature will stay open when the activity is closed so you must kill it before the user quits.
这篇关于Java的不能内螺纹创建处理程序，并没有所谓的活套。prepare（）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
