I’m always getting this warning in Jetty 9 when accessing this Servlet (with GET or POST):
package de.swt1321.servlet;
import java.util.ArrayList;
import java.io.OutputStream;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ServletTest extends HttpServlet {
private static final int UNPROCESSABLE_ENTITY = 422;
private static final java.nio.charset.Charset UTF8 = java.nio.charset.Charset.forName("UTF8");
private ArrayList<Person> persons = new ArrayList<Person>();
@Override
public void doGet(HttpServletRequest req,
HttpServletResponse res) throws ServletException, IOException
{
byte [] HTML = genHTML();
res.setStatus(HttpServletResponse.SC_OK);
res.setHeader("content-type","text/html;charset=utf8");
res.setIntHeader("content-length",HTML.length);
OutputStream os = res.getOutputStream();
os.write(HTML);
os.flush();
}
@Override
public void doPost(HttpServletRequest req,
HttpServletResponse res) throws ServletException, IOException
{
String firstName = req.getParameter("firstName");
String lastName = req.getParameter("lastName");
if(firstName == null || lastName == null) {
res.setStatus(UNPROCESSABLE_ENTITY);
return;
}
persons.add(new Person(req.getParameter("firstName"),req.getParameter("lastName")));
byte[] HTML = genHTML();
res.setStatus(HttpServletResponse.SC_OK);
res.setHeader("content-type","text/html;charset=utf8");
res.setIntHeader("content-length",HTML.length);
OutputStream os = res.getOutputStream();
os.write(HTML);
os.flush();
}
private byte[] genHTML() {
String HTMLString = "<!DOCTYPE html>"+
"<html>"+
"<head>" +
"<title>Hello World!</title>"+
"<style>" +
"table,th,tr { border: 1px solid black;}"+
"</style>" +
"</head>"+
"<body><table><tr><th>First Name</th><th>Last Name</th></tr>";
for(Person person : persons) {
HTMLString += "<tr><td>"+person.firstName+"</td><td>"+person.lastName+"</td></tr>";
}
HTMLString += "</table>"+
"<form name='input' action='/ServletTest-1.0.0/hello' method='post'>"+
"<input type='text' name='firstName'/>"+
"<input type='text' name='lastName'/>" +
"<input type='submit' value='Send me!'/>"+
"</form>" +
"</body>" +
"</html>";
return HTMLString.getBytes(UTF8);
}
private static class Person {
public String firstName;
public String lastName;
public Person(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
}
}
web.xml:
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<servlet>
<servlet-name>HelloWorldServlet</servlet-name>
<display-name>Hello World App</display-name>
<load-on-startup>1</load-on-startup>
<servlet-class>de.swt1321.servlet.ServletTest</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWorldServlet</servlet-name>
<url-pattern>/hello</url-pattern>
</servlet-mapping>
</web-app>
Is this something I should worry about? If yes, how do I fix this? What does this even mean anyway?
This is caused because you are flushing the Output stream.
Simply remove the op.flush(); and let Jetty handle it