SAX的问题

Question

我有下面的代码。

         System.setProperty("http.proxyHost","176.6.129.25") ;
             System.setProperty("http.proxyPort", "8080") ;
Authenticator.setDefault(new MyAuthenticator());
                //http://deadlock.netbeans.org/hudson/api/xml
            *URL url = new URL("http://in8301782d:8080/api/xml");*
            Document dom = new SAXReader().read(url);
            for( Element job : (List<Element>)dom.getRootElement().elements("job")) {
                System.out.println(String.format("Name:%s\tStatus:%s",
                    job.elementText("name"), job.elementText("color")));
            }

如果我用http://deadlock.netbeans.org/hudson/api/xml替换，这段代码可以工作，但它不能与http://in8301782d:8080/api/xml一起工作。事实上，如果我在浏览器中输入相同的东西，它就能正常工作。如果我将主机名替换为Ip地址，也不起作用。

我得到的异常如下所示。

*With in8301782d (machine name)* :

xception in thread "main" org.dom4j.DocumentException: http://in8301782d:8080/api/xml Nested exception: http://in8301782d:8080/api/xml
    at org.dom4j.io.SAXReader.read(SAXReader.java:484)
    at org.dom4j.io.SAXReader.read(SAXReader.java:291)
    at com.sg.hudson.ci.Main.main(Main.java:140)
Nested exception: 
java.io.FileNotFoundException: http://in8301782d:8080/api/xml
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1243)
    at org.apache.xerces.impl.XMLEntityManager.setupCurrentEntity(Unknown Source)
    at org.apache.xerces.impl.XMLVersionDetector.determineDocVersion(Unknown Source)
    at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
    at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
    at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
    at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
    at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
    at org.dom4j.io.SAXReader.read(SAXReader.java:465)
    at org.dom4j.io.SAXReader.read(SAXReader.java:291)
    at com.sg.hudson.ci.Main.main(Main.java:140)

*With Ip (http://176.6.55.55:8080/api/xml):*

Exception in thread "main" org.dom4j.DocumentException: Server returned HTTP response code: 503 for URL: http://176.6.66.156:8080/api/xml Nested exception: Server returned HTTP response code: 503 for URL: http://176.6.66.156:8080/api/xml
    at org.dom4j.io.SAXReader.read(SAXReader.java:484)
    at org.dom4j.io.SAXReader.read(SAXReader.java:291)
    at com.sg.hudson.ci.Main.main(Main.java:140)
Nested exception: 
java.io.IOException: Server returned HTTP response code: 503 for URL: http://176.6.66.156:8080/api/xml
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1245)
    at org.apache.xerces.impl.XMLEntityManager.setupCurrentEntity(Unknown Source)
    at org.apache.xerces.impl.XMLVersionDetector.determineDocVersion(Unknown Source)
    at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
    at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
    at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
    at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
    at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
    at org.dom4j.io.SAXReader.read(SAXReader.java:465)
    at org.dom4j.io.SAXReader.read(SAXReader.java:291)
    at com.sg.hudson.ci.Main.main(Main.java:140)

Answer 1

这似乎不是你的代码的问题。

在第一个异常中，SAX告诉您它找不到http://in8301782d:8080/api/xml -它不能到达这个URL。如果URL在您的浏览器中正常工作，则可能是代理设置有问题。

在第二个异常中，SAX报告服务器返回一个不成功的HTTP状态代码503，which (according to the HTTP specification) means

由于服务器暂时超载或维护，服务器当前无法处理该请求。这意味着这是一种暂时的情况，经过一段时间的延迟后将会得到缓解。

当然，位于此URL的应用程序也可能出于某些非标准原因向您发送HTTP 503。