Question

您好我有这个脚本，我不知道为什么我总是得到req = XMLHTTPRequest是未定义的。你能告诉我我犯了什么错误吗？

var req;


function validate() {
//var idField = document.getElementById("name");
var wrt1 = document.getElementById("p1").value;
var wrt2 = document.getElementById("p2").value;
var data = eval(wrt1)+eval(wrt2);
//  var data = "name=" + encodeURIComponent(idField.value);
req = new XMLHttpRequest();
//  req = new XMLHttpRequest();
var url = "Serwlet";
req.open("POST", url, true);        
req.onreadystatechange = inserter;
req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
req.send(data);
}

function inserter() {
if (req.readyState == 4) {
    if (req.status == 200) {
        var msg = req.responseText
        if (msg == "") {
            //document.getElementById("msg1").innerHTML = "<div style=\"color:red\">"+"COS NIE TAK"+"</div>";
            document.getElementById("msg1").value = '';
        }
        else
            //document.getElementById("msg1").innerHTML = "<div style=\"color:red\">"+wynik+"</div>";
            document.getElementById("msg1").value = "IT WORKS";
    }
}

}

修改的

好的，我做了一些改进。现在唯一的问题是来自JavaScript inserter（）的msg总是空的; /，不知道为什么，如果你看一下验证方法var数据有正确的值，msg总是为null; /。

package Pakiet;


import java.io.IOException;
import java.io.PrintWriter;
import java.io.Writer;

import javax.servlet.ServletException;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.Writer;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/Serwlet")
public class Serwlet extends HttpServlet {
private static final long serialVersionUID = 1L;
static String KOD =
/*

     out.print("<FORM ACTION=\"ExerciseE\" name=\"entryForm\">\n"+
                        "Name:<INPUT TYPE=\"TEXT\" NAME=\"name\"><BR>\n"+
                        "<INPUT TYPE=\"BUTTON\" VALUE=\"SUBMIT\"\n" +
                        " OnClick=\"validate()\">\n</FORM>");       
 */
"<html>"+
"<head>"+
 "<meta http-equiv=\"Content-Type\" content=\"text/html; charset=windows-1250\">"+
"<title>Testowanie</title>"+
"<script type=\"text/javascript\" language=\"javascript\" src=\"servletD2Script.js\"></script>"+
"</head>"+
"<body>"+
"<div id=\"msg1\">Pierwsza suma</div>"+
"<div id=\"msg2\">Pierwsza suma</div>"+
"<center><h2>Testowanie parametrów</h2></center>"+
"<hr>"+
"<form method=\"get\" action=\"Serwlet\">"+
"p1<input type=\"text\" size=\"50\" name=\"p1\" onblur=\"validate()\"><br>"+
"p2<input type=\"text\" size=\"50\" name=\"p2\" onblur=\"validate()\"><br>"+
"<br><input type=\"submit\" value=\"Wyślij formularz by GET\">"+
"</form>"+
"</hr>"+
"<hr>"+
"<form method=\"post\" action=\"Serwlet\">"+
"p3<input type=\"text\" size=\"50\" name=\"p3\" onblur=\"funkcja()\"><br>"+
"p4<input type=\"text\" size=\"50\" name=\"p4\" onblur=\"funkcja()\"><br>"+
"<br><input type=\"submit\" value=\"Wyślij formularz by POST\">"+
"</form>"+
"</hr>"+

"</body></html>";

public Serwlet() {
    super();

}
static boolean raz = true;
private void serviceRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

      response.setContentType("text/html");
      response.setHeader("Cache-Control", "no-cache");
      PrintWriter out = response.getWriter();
      if(raz){out.print(Serwlet.KOD);raz = false;}
      String name = request.getParameter("name");   // dostaję nazwisko
      String org = ""; //jakas wartosc 
      out.write(org != null ?  org : "");    // zwracam organizację lub pusty napis, jesli nie znam nazwiska
}


protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    serviceRequest( request, response);
}


protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    serviceRequest( request, response);
}

}

和脚本 //方法FUNCKJA（）并非重要

  function funkcja(){
var wrt1 = document.getElementById("p1").value;
var wrt2 = document.getElementById("p2").value;
var wynik = eval(wrt1)+eval(wrt2);
document.getElementById("msg1").innerHTML = "<div style=\"color:red\">"+wynik+"</div>";
var wrt3 = document.getElementById("p3").value;
var wrt4 = document.getElementById("p4").value;
var wynik2 = eval(wrt3)+eval(wrt4);
document.getElementById("msg2").innerHTML = "<div style=\"color:red\">"+wynik2+"</div>";
}


var req;

function validate() {
//var idField = document.getElementById("name");
var wrt1 = document.getElementById("p1").value;
var wrt2 = document.getElementById("p2").value;
var data = eval(wrt1)+eval(wrt2)+"";

if (typeof XMLHttpRequest != "undefined") {
    req = new XMLHttpRequest();
} else if (window.ActiveXObject) {
    req = new ActiveXObject("Microsoft.XMLHTTP");
}
var url = "Serwlet";
req.open("POST", url, true);      
req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
alert("data = "+data);
req.send(data);
req.onreadystatechange = inserter;
}




function inserter() {
if (req.readyState == 4) {
    if (req.status == 200) {
        var msg = req.responseText;
        alert("msg = "+msg);
        if (msg == "") {
            document.getElementById("msg1").innerHTML = "<div style=\"color:red\">"+"COS NIE TAK"+"</div>";
            //document.getElementById("msg1").value = "blabla";
        }
        else
            document.getElementById("msg1").innerHTML = "<div style=\"color:red\">"+msg+"</div>";
            //document.getElementById("msg1").value = "COOOO JEST";
    }
}
}

Answer 1

而不是req = new XMLHttpRequest试试这个：

if(window.XMLHttpRequest && !(window.ActiveXObject)) {  
        try {  
            req = new XMLHttpRequest();  
        } catch(e) {  
            req = false;  
        }  

    } else if(window.ActiveXObject) {  

        try {  
            req = new ActiveXObject("Msxml2.XMLHTTP");  
        } catch(e) {  
            try {  
                req = new ActiveXObject("Microsoft.XMLHTTP");  
            } catch(e) {  
                req = false;  
            }  
        }  
    }

偏离主题：如果ajax是您的要求，您应该考虑使用某些库，例如： jQuery的。

编辑：

根据评论：

if(raz){out.print(Serwlet.KOD);raz = false;}

你能检查raz是否真实吗？

然后写入流程调用out.flush();

if(raz){ 
   out.print(Serwlet.KOD);
   raz = false;
}
String name = request.getParameter("name");   // dostaję nazwisko
String org = ""; //jakas wartosc 
out.write(org != null ?  org : "");
out.flush();

XMLHttpRequest（）是未定义的Servlet

1 个答案: