通过JAVA的net包实现JAVA http接口访问错误总结 500

今天在测试http短信接口时，犯了个错误，导致一天工作下来都不爽，晚上回来调试了很久，总算找到问题所在，竟然很简单，甚感羞愧，特此记录，以绝再犯。

错误代码：

URL myUrl = new URL( "http://sms.hcsdsms.com:8080/SmsService/SmsService.asmx/SendEx?"
            + "UserId=XXXXXX&Password=XXXXXX&MsgContent=短信测试"
            + "&DestNumber=15817611***&SendTime=&SubNumber="
            + "&BizType=22&WapURL=&BatchSendID=" );
HttpURLConnection conn = (HttpURLConnection) myUrl.openConnection();
conn.setDoOutput( true );
conn.setDoInput( true );
OutputStreamWriter osw = new OutputStreamWriter(conn.getOutputStream());
osw.write( "" );
osw.flush();
osw.close();
BufferedReader br = new BufferedReader( new InputStreamReader(conn.getInputStream()));
String s = null ;
while ((s = br.readLine()) != null ) {
     sb.append(s);
}

当执行程序时，控制台报500错误：

java.io.IOException: Server returned HTTP response code: 500 for URL: http: //sms.hcsdsms.com:8080/SmsService/SmsService.asmx/SendEx?UserId=XXXXXX&Password=XXXXXX&MsgContent=短信测试&DestNumber=15817611***&SendTime=&SubNumber=&BizType=22&WapURL=&BatchSendID=
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at sms.SmsHttpTest.doHttp(SmsHttpTest.java: 43 )
at sms.SmsHttpTest.test(SmsHttpTest.java: 23 )

-----------------------------------------------------------

正确代码： 
      

URL myUrl = new URL( "http://sms.hcsdsms.com:8080/SmsService/SmsService.asmx/SendEx?" );
HttpURLConnection conn = (HttpURLConnection) myUrl.openConnection();
conn.setDoOutput( true );
conn.setDoInput( true );
OutputStreamWriter osw = new OutputStreamWriter(conn.getOutputStream());
osw.write( "UserId=XXXXXX&Password=XXXXXX&MsgContent=短信测试"
            + "&DestNumber=15817611***&SendTime=&SubNumber="
            + "&BizType=22&WapURL=&BatchSendID=" );
osw.flush();
osw.close();
BufferedReader br = new BufferedReader( new InputStreamReader(conn.getInputStream()));
String s = null ;
while ((s = br.readLine()) != null ) {
          sb.append(s);
}

执行程序，得到返回的XML结构数据：

<? xml version = "1.0" encoding = "utf-8" ?>< SendExResp xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd = "http://www.w3.org/2001/XMLSchema" xmlns = "http://tempuri.org/" >  < PayCount >1</ PayCount >  < BlackWords />  < ErrorMobiles />  < BlackMobiles />  < BatchSendID >00000000-0000-0000-0000-000000000000</ BatchSendID >  < Result >0</ Result >  < ErrorDesc >成功</ ErrorDesc ></ SendExResp >

-------------------------------------------------------

详解：

通过url字符串构造java.net.URL对象，并打开连接（myUrl.openConnection()）时，实际上只针对URL中的访问路径http://sms.hcsdsms.com:8080/SmsService/SmsService.asmx/SendEx?建立了连接，而后面的一系列参数串并不是建立连接的有效部分，所以被舍去了。当访问API时，由于服务端强制要求相应的参数必不可少，在建立连接后也没有把相应的参数通过输出流write到服务端，所以程序报错。

在正确的代码中，通过将服务端强制要求的必需参数write到输出流中，实现了正常的访问，得到了正确的返回结果

http://my.oschina.net/ichatter/blog/76487