修改： see here!
我有一个带有Runnable的线程，如下所示。它有一个问题，我无法弄清楚：我在线程上调用interrupt()的一半时间（为了停止它）它实际上没有终止（InterruptedException没有被捕获）。
private class DataRunnable implements Runnable {
@Override
public void run() {
Log.d(TAG, "DataRunnable started");
while (true) {
try {
final String currentTemperature = HeatingSystem.get("currentTemperature");
mView.post(() -> showData(currentTemperature));
} catch (ConnectException e) {
mView.post(() -> showConnectionMessage());
break;
}
try {
Thread.sleep(10);
} catch (InterruptedException e) {
break;
}
}
Log.d(TAG, "DataRunnable terminated");
}
}
问题是执行长网络操作的HeatingSystem.get(String)方法。我想在那个方法的某个地方重置了中断的标志，但我找不到那个语句会做什么（我没有在参考文献中提到的所有类中提到它，如HttpURLConnection）。方法如下（不是我写的）。
/**
* Retrieves all data except for weekProgram
* @param attribute_name
* = { "day", "time", "currentTemperature", "dayTemperature",
* "nightTemperature", "weekProgramState" }; Note that
* "weekProgram" has not been included, because it has a more
* complex value than a single value. Therefore the funciton
* getWeekProgram() is implemented which return a WeekProgram
* object that can be easily altered.
*/
public static String get(String attribute_name) throws ConnectException,
IllegalArgumentException {
// If XML File does not contain the specified attribute, than
// throw NotFound or NotFoundArgumentException
// You can retrieve every attribute with a single value. But for the
// WeekProgram you need to call getWeekProgram().
String link = "";
boolean match = false;
String[] valid_names = {"day", "time", "currentTemperature",
"dayTemperature", "nightTemperature", "weekProgramState"};
String[] tag_names = {"current_day", "time", "current_temperature",
"day_temperature", "night_temperature", "week_program_state"};
int i;
for (i = 0; i < valid_names.length; i++) {
if (attribute_name.equalsIgnoreCase(valid_names[i])) {
match = true;
link = HeatingSystem.BASE_ADDRESS + "/" + valid_names[i];
break;
}
}
if (match) {
InputStream in = null;
try {
HttpURLConnection connect = getHttpConnection(link, "GET");
in = connect.getInputStream();
/**
* For Debugging Note that when the input stream is already used
* with this BufferedReader, then after that the XmlPullParser
* can no longer use it. This will cause an error/exception.
*
* BufferedReader inn = new BufferedReader(new
* InputStreamReader(in)); String testLine = ""; while((testLine
* = inn.readLine()) != null) { System.out.println("Line: " +
* testLine); }
*/
// Set up an XML parser.
XmlPullParser parser = Xml.newPullParser();
parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES,
false);
parser.setInput(in, "UTF-8"); // Enter the stream.
parser.nextTag();
parser.require(XmlPullParser.START_TAG, null, tag_names[i]);
int eventType = parser.getEventType();
// Find the single value.
String value = "";
while (eventType != XmlPullParser.END_DOCUMENT) {
if (eventType == XmlPullParser.TEXT) {
value = parser.getText();
break;
}
eventType = parser.next();
}
return value;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
System.out.println("FileNotFound Exception! " + e.getMessage());
// e.printStackTrace();
} catch (XmlPullParserException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (in != null)
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
} else {
// return null;
throw new IllegalArgumentException("Invalid Input Argument: \""
+ attribute_name + "\".");
}
return null;
}
/**
* Method for GET and PUT requests
* @param link
* @param type
* @return
* @throws IOException
* @throws MalformedURLException
* @throws UnknownHostException
* @throws FileNotFoundException
*/
private static HttpURLConnection getHttpConnection(String link, String type)
throws IOException, MalformedURLException, UnknownHostException,
FileNotFoundException {
URL url = new URL(link);
HttpURLConnection connect = (HttpURLConnection) url.openConnection();
connect.setReadTimeout(HeatingSystem.TIME_OUT);
connect.setConnectTimeout(HeatingSystem.TIME_OUT);
connect.setRequestProperty("Content-Type", "application/xml");
connect.setRequestMethod(type);
if (type.equalsIgnoreCase("GET")) {
connect.setDoInput(true);
connect.setDoOutput(false);
} else if (type.equalsIgnoreCase("PUT")) {
connect.setDoInput(false);
connect.setDoOutput(true);
}
connect.connect();
return connect;
}
有人知道上述方法中可能导致问题的原因吗？
Thread.sleep()在调入InterruptException之前也会interrupt()投出Thread.sleep()：Calling Thread.sleep() with *interrupted status* set?。
我检查了中断后是否到达Thread.sleep()，并且已到达。
这是DataRunnable的启动和中断方式（我总是得到“onPause called”日志）：
@Override
public void onResume() {
connect();
super.onResume();
}
@Override
public void onPause() {
Log.d(TAG, "onPause called");
mDataThread.interrupt();
super.onPause();
}
private void connect() {
if (mDataThread != null && mDataThread.isAlive()) {
Log.e(TAG, "mDataThread is alive while it shouldn't!"); // TODO: remove this for production.
}
setVisibleView(mLoading);
mDataThread = new Thread(new DataRunnable());
mDataThread.start();
}
答案 0 :(得分：3)
这不是一个真正的答案，但我不知道该把它放在哪里。通过进一步调试，我认为我遇到了奇怪的行为，我能够在测试类中重现它。现在我很好奇这是否真的是我怀疑的错误行为，以及其他人是否可以重现它。我希望这可以写出来作为答案。
（最好把它变成一个新问题，或者实际上只是提交错误报告？）
下面是测试类，它必须在Android上运行，因为它是关于getInputStream()调用，它在Android上表现不同（不知道确切原因）。在Android上，getInputStream()会在中断时抛出InterruptedIOException。下面的线程循环并在一秒钟后被中断。因此，当它被中断时，getInputStream()应该抛出异常，并且应该使用catch块捕获异常。这有时会正常工作，但大多数情况下不会抛出异常！而是仅重置中断的标志，从而将中断的== true更改为中断的== false，然后由if捕获。 if中的消息弹出给我。这在我看来是错误的行为。
import java.net.HttpURLConnection;
import java.net.URL;
class InterruptTest {
InterruptTest() {
Thread thread = new Thread(new ConnectionRunnable());
thread.start();
try {
Thread.sleep(1000);
} catch (InterruptedException e) {}
thread.interrupt();
}
private class ConnectionRunnable implements Runnable {
@Override
public void run() {
while (true) {
try {
URL url = new URL("http://www.google.com");
HttpURLConnection connect = (HttpURLConnection) url.openConnection();
boolean wasInterruptedBefore = Thread.currentThread().isInterrupted();
connect.getInputStream(); // This call seems to behave odd(ly?)
boolean wasInterruptedAfter = Thread.currentThread().isInterrupted();
if (wasInterruptedBefore == true && wasInterruptedAfter == false) {
System.out.println("Wut! Interrupted changed from true to false while no InterruptedIOException or InterruptedException was thrown");
break;
}
} catch (Exception e) {
System.out.println(e.getClass().getName() + ": " + e.getMessage());
break;
}
for (int i = 0; i < 100000; i += 1) { // Crunching
System.out.print("");
}
}
System.out.println("ConnectionThread is stopped");
}
}
}
答案 1 :(得分：2)
我过去一直在努力解决类似的问题，但我从未找到过令人满意的解决方案。总是对我有用的唯一解决方法是引入一个volatile布尔“stopRequested”成员变量，该变量设置为true以便中断Runnable并检查Runnable的while条件而不是Thread的中断状态。
关于我的经历的不幸细节是，我从来没有能够提取一个重现这个问题的小型可编辑示例。你能做到吗？ 如果你无法做到这一点，我有兴趣知道你是否肯定你正在使用正确的mDataThread实例？ 您可以通过记录其哈希码来验证这一点......
答案 2 :(得分：0)
您需要将while循环更改为：
// You'll need to change your while loop check to this for it to reliably stop when interrupting.
while(!Thread.currentThread().isInterrupted()) {
try {
final String currentTemperature = HeatingSystem.get("currentTemperature");
mView.post(() -> showData(currentTemperature));
} catch (ConnectException e) {
mView.post(() -> showConnectionMessage());
break;
}
try {
Thread.sleep(10);
} catch (InterruptedException e) {
break;
}
}
而不是while(true)。
请注意，Thread.interrupted()和Thread.currentThread().isInterrupted()执行不同的操作。第一个在检查后重置中断状态。后者使状态保持不变。