ajax

来源：互联网发布：java apache httppost 编辑：程序博客网时间：2024/06/06 04:22

页面代码

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>  <%  String path = request.getContextPath();  String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";  %>    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">  <html>    <head>      <base href="<%=basePath%>">            <title>My JSP '14-4-21_AJAS_logon.jsp' starting page</title>            <meta http-equiv="pragma" content="no-cache">      <meta http-equiv="cache-control" content="no-cache">      <meta http-equiv="expires" content="0">          <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">      <meta http-equiv="description" content="This is my page">      <!--     <link rel="stylesheet" type="text/css" href="styles.css">     -->        </head>    <script type="text/javascript">    var xhr=null;        function checkUname(){        var username=document.myform.uname.value;        if(username==""||username==null){              document.getElementById("msgDiv").innerHTML="<font color='red'>请输入用户名</font>";            }                    if(window.ActiveXObject){              xhr=new ActiveXObject("Microsoft.XMLHTTP");              }else{                  xhr=new XMLHttpRequest();//只对非IE浏览器生效                                    }                var url="http://localhost:8080/Five_0001_Kt/TestServlet_005_14421_Login?uname="+username;          url=encodeURI(url);          url=encodeURI(url); //两次编码          xhr.onreadystatechange=haolejiaowo;   //当核心对象状态发生改变，它的处理函数          xhr.open("post",url,true);          xhr.send(null);                  }    function haolejiaowo(){        if(xhr.readyState==4&&xhr.status==200){          var result=xhr.responseText;//得到远程服务器返回的结果          if(result.indexOf("true")!=-1){            document.getElementById("msgDiv").innerHTML="<font color='red'>用户名已存在</font>";;          }else{            document.getElementById("msgDiv").innerHTML="可以注册";          }          }        }          </script>            <body>      <form action="#" method="post" name="myform" >          <input type="text" name="uname" onblur="checkUname()"/>      <div id="msgDiv" style="display:inline">aaa</div>      <br/>      <input type="submit"value="注册">       </form>                      </body>  </html>

servlet

package PractiseServlet;    import java.io.IOException;  import java.io.PrintWriter;    import javax.servlet.ServletException;  import javax.servlet.http.HttpServlet;  import javax.servlet.http.HttpServletRequest;  import javax.servlet.http.HttpServletResponse;    public class TestServlet_005_14421_Login extends HttpServlet {        public boolean isExist(String name){          boolean flag=false;          String []names={"admin","123","何彦柱"};          for(String s:names){              if(name.equals(s)) flag=true;          }          return flag;      }            public void doGet(HttpServletRequest request, HttpServletResponse response)              throws ServletException, IOException {          this.doPost(request, response);      }          public void doPost(HttpServletRequest request, HttpServletResponse response)              throws ServletException, IOException {          response.setContentType("text/html;charset=utf-8");                    PrintWriter out = response.getWriter();                String username=request.getParameter("uname");          username = java.net.URLDecoder.decode(username, "UTF-8");//一次解码          System.out.println(username);          boolean flag=isExist(username);          out.println(flag);                    out.flush();          out.close();                    }    }

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