java - Android:我如何捕捉这个异常

我希望这将是一个简单的。

我重用了教程中的代码，该代码在 ListView 中解析和显示 RSS
从代理后面或没有互联网运行代码时，我收到以下崩溃报告:

12-12 09:48:57.372: W/RssApp(1494): Exception while retrieving the input stream
12-12 09:48:57.372: W/RssApp(1494): java.net.ConnectException: failed to connect to gigglepics.co.uk/188.121.41.139 (port 80): connect failed: ETIMEDOUT (Connection timed out)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.io.IoBridge.connect(IoBridge.java:114)
12-12 09:48:57.372: W/RssApp(1494):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
12-12 09:48:57.372: W/RssApp(1494):     at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
12-12 09:48:57.372: W/RssApp(1494):     at java.net.Socket.connect(Socket.java:842)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:76)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:340)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:316)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.net.http.HttpEngine.connect(HttpEngine.java:311)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:290)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:240)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:282)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:177)
12-12 09:48:57.372: W/RssApp(1494):     at eu.MasterZangetsu.RssService.getInputStream(RssService.java:48)
12-12 09:48:57.372: W/RssApp(1494):     at eu.MasterZangetsu.RssService.onHandleIntent(RssService.java:33)
12-12 09:48:57.372: W/RssApp(1494):     at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:65)
12-12 09:48:57.372: W/RssApp(1494):     at android.os.Handler.dispatchMessage(Handler.java:99)
12-12 09:48:57.372: W/RssApp(1494):     at android.os.Looper.loop(Looper.java:137)
12-12 09:48:57.372: W/RssApp(1494):     at android.os.HandlerThread.run(HandlerThread.java:60)
12-12 09:48:57.372: W/RssApp(1494): Caused by: libcore.io.ErrnoException: connect failed: ETIMEDOUT (Connection timed out)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.io.Posix.connect(Native Method)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:85)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
12-12 09:48:57.372: W/RssApp(1494):     at libcore.io.IoBridge.connect(IoBridge.java:112)
12-12 09:48:57.372: W/RssApp(1494):     ... 20 more
12-12 09:48:57.382: W/dalvikvm(1494): threadid=11: thread exiting with uncaught exception (group=0x40a71930)
12-12 09:48:57.402: E/AndroidRuntime(1494): FATAL EXCEPTION: IntentService[RssService]
12-12 09:48:57.402: E/AndroidRuntime(1494): java.lang.NullPointerException
12-12 09:48:57.402: E/AndroidRuntime(1494):     at eu.MasterZangetsu.PcWorldRssParser.parse(PcWorldRssParser.java:33)
12-12 09:48:57.402: E/AndroidRuntime(1494):     at eu.MasterZangetsu.RssService.onHandleIntent(RssService.java:33)
12-12 09:48:57.402: E/AndroidRuntime(1494):     at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:65)
12-12 09:48:57.402: E/AndroidRuntime(1494):     at android.os.Handler.dispatchMessage(Handler.java:99)
12-12 09:48:57.402: E/AndroidRuntime(1494):     at android.os.Looper.loop(Looper.java:137)
12-12 09:48:57.402: E/AndroidRuntime(1494):     at android.os.HandlerThread.run(HandlerThread.java:60)

这发生在 inputStream.close();

    public List<RssItem> parse(InputStream inputStream)
        throws XmlPullParserException, IOException {
    try {
        XmlPullParser parser = Xml.newPullParser();
        parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
        parser.setInput(inputStream, null);
        parser.nextTag();
        return readFeed(parser);
    } finally {
        inputStream.close();

    }
}

我想要做的就是捕获此异常以确保应用程序不会崩溃而是显示错误消息

我尝试的一切似乎仍然崩溃并给出完全不同的错误。我一定错过了一些非常基本的东西

最佳答案

代码缺少实际的 catch 语句:

try {
    XmlPullParser parser = Xml.newPullParser();
    parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
    parser.setInput(inputStream, null);
    parser.nextTag();
    return readFeed(parser);
}catch(IllegalArgumentException e){ //Replace this with the more specific exception
  //do something
}catch(Excpetion e){ //You can have multiple catch blocks from specific to general
  //do something
}finally {
    inputStream.close();

}

添加此代码后，您仍然会收到错误消息，因为 inputStream 为空并在 NullPointerException 块中抛出 finally。有两种方法可以处理这个问题。

第一种是简单地捕获 NullPointerException 块中的 finally:

try {
    XmlPullParser parser = Xml.newPullParser();
    parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
    parser.setInput(inputStream, null);
    parser.nextTag();
    return readFeed(parser);
}catch(IllegalArgumentException e){ //Replace this with the more specific exception
  //do something
}catch(Excpetion e){ //You can have multiple catch blocks from specific to general
  //do something
}finally {
    try{
       inputStream.close();
    }catch(Exception e){
       //do something
    }
}

第二个是不通过添加保护条件在方法的开头不接受空的 InputStream。

public List<RssItem> parse(InputStream inputStream)
    throws IllegalArgumentException {

    if(inputStream == null){
        throw new IllegalArgumentException();
    }
}

可以这样称呼:

  try{
        someObject.parse(null);
  }catch(IllegalArgumentException e){
      //do something
  }

关于java - Android:我如何捕捉这个异常，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/20539728/