Question

我使用jquery来向一个servlet发送ajax请求。

现在使用这样的GET请求时：

$("#nbtnLogin").click(function(){

       login=$("#nloginIn").val();
      passwd=$("#npasswdIn").val();
      //alert(login + "   " + passwd);
      $.get(
        "http://localhost:8080/EsLab2-Servlet-AsyncServerandClient/EsLab2Servlet",
        {login:login, passwd:passwd, type:"i"},
       function(data,stato){
            alert("dati: " + data + "\n stato: " + stato);
            $("#ajaxResponse1").empty().append(data +"\n");
        },"text"
    );

一切正常，但我得到回应，但是当我在$.get

中更改$.post时

$("#nbtnLogin").click(function(){

       login=$("#nloginIn").val();
      passwd=$("#npasswdIn").val();
      //alert(login + "   " + passwd);
      $.post(
        "http://localhost:8080/EsLab2-Servlet-AsyncServerandClient/EsLab2Servlet",
        {login:login, passwd:passwd, type:"i"},
       function(data,stato){
            alert("dati: " + data + "\n stato: " + stato);
            $("#ajaxResponse1").empty().append(data +"\n");
        },"text"
    );

最初保持待定状态，几秒钟后我收到错误代码500为什么？

package MyServlet;

import java.io.IOException;

import java.util.HashMap;
import java.util.Map;
import javax.servlet.AsyncContext;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


@WebServlet(name="EsLab2Servlet",asyncSupported = true)
public class EsLab2Servlet extends HttpServlet {

Map<String, String> hashmap;

public EsLab2Servlet() {
    hashmap=new HashMap<String, String>();
}


/**
 * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
 * methods.
 *
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
 protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
   // response.setContentType("text/html;charset=UTF-8");
    //PrintWriter out = response.getWriter();

 final AsyncContext context = request.startAsync();
    response.setContentType("text/plain");
    response.setCharacterEncoding("UTF-8");
    final ServletInputStream input = request.getInputStream();
    final ServletOutputStream output = response.getOutputStream();
    System.out.println("ciao");

    input.setReadListener(new ReadListenerImpl(input, output, context, hashmap));

  // context.complete();
}

// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the +    sign on the left to edit the code.">
/**
 * Handles the HTTP <code>GET</code> method.
 *
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    processRequest(request, response);
}

/**
 * Handles the HTTP <code>POST</code> method.
 *
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    processRequest(request, response);
}

/**
 * Returns a short description of the servlet.
 *
 * @return a String containing servlet description
 */
@Override
public String getServletInfo() {
    return "Short description";
}// </editor-fold>

}

和

package MyServlet;

import java.io.IOException;

import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.AsyncContext;
import javax.servlet.ReadListener;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.swing.JOptionPane;


class ReadListenerImpl implements ReadListener {
private ServletInputStream input;
private ServletOutputStream output;
private AsyncContext context;
private  Map<String, String> hashmap;

ReadListenerImpl(ServletInputStream input, ServletOutputStream output, AsyncContext    context , Map hashmap) {
    this.input = input;
    this.output = output;
    this.context = context;
    this.hashmap = hashmap;
}


 //metodi
 protected synchronized String processLogin(HttpServletRequest request)throws  ServletException, IOException{

String user = null;
String passwd= null;
String cont=null;

user=request.getParameter("login").toString();
passwd=request.getParameter("passwd").toString();
//cont = "Hello" + user + passwd;


if(passwd.equals("")){
cont="inserire password!";
}
else {
if((hashmap.containsKey(user))){
if((hashmap.get(user).compareTo(passwd))==0)
cont="login: OK";
else cont="login: Abort";
}
else cont="login: Abort";
/*hashmap.put(user,passwd);
cont=cont + "elemento inserito";
*/
}

return cont;
}

protected synchronized String processInsert(HttpServletRequest request)throws ServletException, IOException{

String user = null;
String passwd= null;
String cont=null;

user=request.getParameter("login").toString();
passwd=request.getParameter("passwd").toString();
//cont = "Hello" + user + passwd;

if(passwd.equals("") || user.equals("")){
cont="malformed request";
}
else {
if((hashmap.containsKey(user))){
cont="utente già presente";
}
else {
hashmap.put(user, passwd);
cont="insert: Ok";
}

}

    return cont;
}

protected synchronized String processView(HttpServletRequest request)throws   ServletException, IOException{
String cont = null;
String user = null;
user=request.getParameter("login").toString();
if((hashmap.containsKey(user))){
cont=hashmap.get(user);
}
else cont="utente non presente!";
     return cont;
}

@Override
public void onDataAvailable() throws IOException {

 System.out.println("onDataAvailable");



}

@Override
public void onAllDataRead() throws IOException {

System.out.println("ricevuti tutti i dati!...lancio il thread..."); 

context.start(new Runnable() {
String cont = null;
@Override
public void run() {

try {
System.out.println("Sono il thread adesso lavoro e poi ritorno disponibile...");

HttpServletRequest req = (HttpServletRequest) context.getRequest();

if (req.getParameter("type").compareTo("l") == 0 ) cont=processLogin(req);
else if (req.getParameter("type").compareTo("i") == 0) cont=   processInsert(req);
else if (req.getParameter("type").compareTo("s") == 0) cont= processView(req);

output.println(cont);
output.flush();




} catch (ServletException ex) {
Logger.getLogger(ReadListenerImpl.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(ReadListenerImpl.class.getName()).log(Level.SEVERE, null, ex);
} finally{

try {
input.close();
output.close();
context.complete();
} catch (IOException ex) {
Logger.getLogger(ReadListenerImpl.class.getName()).log(Level.SEVERE, null, ex);
}
}

}

});
}

  @Override
   public void onError(Throwable t) {
       System.out.println("c'è un errore");


 } 


 }

Answer 1

如果您没有读取所有数据，则不会调用onAllDataRead上的回调。下面是一个例子：

final ServletInputStream input = request.getInputStream();
input.setReadListener(new ReadListener() {

           @Override
           public void onDataAvailable() throws IOException {
                byte b[]=new byte[1024];
                while(input.isReady()&&input.read(b)!=-1){
                }

           }

           @Override
           public void onAllDataRead() throws IOException {
               context.getResponse().getWriter().write("ciao");
               context.complete();
           }

           @Override
           public void onError(Throwable t) {
                context.complete();                       
           }

});

错误500使用带有jquery的POST请求

1 个答案: