Mike
On Tuesday, January 28, 2003, at 07:52 AM, Dave Walsh wrote:
I saw your post and response, I have seen this guy alot on this forum. I dod't myself know why we need a multipart form at this point, so if it was omething that I said, ignore that for now.
Dave
Daniel Walsh wrote:
In trying to get to know the HttpClient component a bit, I attempted to write a simple program using a Java Servlet and the HttpClient API - the end result being that the client make a post to the servlet and the servlet return a brief HTML response to the client. The next step would be to transfer a file between the two, however, I'm running into some trouble with this first step.
The only real requirements I've placed on this step is to use a post method instead of a get (because future steps would not be able to use a get), and to pass a parameter in the request. The parameter is where my problems start. After checking for this parameter on the server side, I throw an exception if it is non-existent. This is as far as the program has been running for me.
I'm using HTTP Client 2.0 Alpha 2, and Commons Logging 1.0.2. I've included a couple of example classes that represent the basics of my code, and the thrown exception, in case anyone might have an idea as to what I am doing wrong:
______________________________________________________________________ ___________________________
CLIENT CLASS -
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.methods.*;
import java.io.*;
import java.net.*;
public class HttpClientExmpl
{
public HttpClientExmpl()
{
init();
}
public void init()
{
MultipartPostMethod postMethod = new MultipartPostMethod();
postMethod.setPath("/servlet/HttpClientExmplServlet");
postMethod.addParameter("param-name", "param-value");
HttpClient client = new HttpClient();
HostConfiguration hostConfig = new HostConfiguration();
hostConfig.setHost("localhost", 8081, "http");
client.setConnectionTimeout(30000);
client.setHostConfiguration(hostConfig);
try
{
client.executeMethod(postMethod);
}
catch(HttpException httpEx)
{
httpEx.printStackTrace();
}
catch(IOException ioEx)
{
ioEx.printStackTrace();
}
String responseString = postMethod.getResponseBodyAsString();
postMethod.releaseConnection();
System.out.println(responseString);
}
public static void main(String args[])
{
new HttpClientExmpl();
}
}
______________________________________________________________________ ___________________________
SERVLET CLASS -
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class HttpClientExmplServlet extends HttpServlet
{
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
String paramValue = request.getParameter("param-name");
if(paramValue == null)
throw new ServletException(new NullPointerException("The getParameter call returned null."));
response.setContentType("text/html");
PrintWriter writer = response.getWriter();
StringBuffer buf = new StringBuffer();
buf.append("<HTML>\n");
buf.append("<HEAD>\n<TITLE>HTTP Client Example Application</TITLE>\n</HEAD>\n");
buf.append("<BODY>\n");
buf.append("The servlet received the parameter sent within the post method.\n");
buf.append("</BODY>\n");
buf.append("</HTML>");
writer.write(buf.toString());
writer.flush();
writer.close();
}
}
______________________________________________________________________ ___________________________
RESULTING EXCEPTION -
2003-01-27 21:08:27 StandardWrapperValve[HttpClientExmplServlet]: Servlet.service() for servlet HttpClientExmplServlet threw exception
java.lang.NullPointerException: The getParameter call returned null.
at HttpClientExmplServlet.doPost(HttpClientExmplServlet.java:14)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appli cationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFi lterChain.java:193)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(Monitor Filter.java:223)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appli cationFilterChain.java:213)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFi lterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperVa lve.java:243)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline. java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java :472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextVa lve.java:190)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline. java:566)
at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve. java:246)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline. java:564)
at org.netbeans.modules.web.monitor.catalina.MonitorValve.invoke(MonitorV alve.java:142)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline. java:564)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java :472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2 347)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.ja va:180)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline. java:566)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcher Valve.java:170)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline. java:564)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.ja va:170)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline. java:564)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:4 68)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline. java:564)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java :472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValv e.java:174)
at org.apache.catalina.core.StandardPipeline.invokeNext(StandardPipeline. java:566)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java :472)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:943)
at org.apache.catalina.connector.http.HttpProcessor.process(HttpProcessor .java:1027)
at org.apache.catalina.connector.http.HttpProcessor.run(HttpProcessor.jav a:1125)
at java.lang.Thread.run(Thread.java:536)
Any suggestions would be greatly appreciated.
Thanks,
Daniel
p.s. I'm not even sure that MultipartPostMethod is the most suitable object for this. If not, I'd appreciate a point in the right direction.
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