java - 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")));
            }

如果我替换为http://deadlock.netbeans.org/hudson/api/xml，则此代码可以正常工作。 ，但它不适用于 http://in8301782d:8080/api/xml 。事实上，如果我在浏览器中输入相同的内容，它就可以工作。如果我用 IP 地址替换主机名，它也不起作用。

我遇到的异常如下。

*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

这似乎不是您的代码的问题。

在第一个异常中，SAX 告诉您它找不到 http://in8301782d:8080/api/xml - 无法到达此 URL。如果该 URL 在您的浏览器中有效，则代理设置可能有问题。

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

The server is currently unable to handle the request due to a temporary overloading or maintenance of the server. The implication is that this is a temporary condition which will be alleviated after some delay.

当然，位于此 URL 的应用程序也可能会出于某种非标准原因向您发送 HTTP 503。