Jquery+ajax+JAVA (servlet) implements asynchronous value collection of drop-down menu

Jquery+ajax+JAVA (servlet) implements asynchronous value collection of drop-down menu_jquery

WBOY

Release： 2016-05-16 15:08:24

Original

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First look at the project structure diagram:

The packages required by the project are as follows:

JSP code:

<%@ page language="java" import="java.util.*" pageEncoding="GBK"%>
<%
  String path = request.getContextPath();
  String basePath = request.getScheme() + "://"
      + request.getServerName() + ":" + request.getServerPort()
      + path + "/";
      System.out.println("basePath="+basePath);
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>JsonCase</title>
<script type="text/javascript" src="<%=basePath %>js/jquery-1.7.2.min.js"></script>
<script type="text/javascript">
  $(function($) {
    $("#record").append("当前测试页面完成加载。<br/>");
  });
  function getFirstFloorValue(element) {
    $("#record").append("<br/>获取到信息：您将要取得第一级选项信息……");
    $("#record").append("<br/>正在使用ajax为您获取数据，您可以继续停留在页面并进行其他操作。");
    $.ajax({
      url : 'ValueGetController',
      type : 'post',
      data : 'action=GetFirstFloorValue',
      datatype : 'json',
      success : function(data) {
        $("#record").append("<br/>操作成功，正在为您准备数据……");
        $(element).empty();
        $("#record").append("<br/>清除原始数据成功！");
        var ops = $.parseJSON(data);
        $("#record").append("<br/>即时数据准备成功！");
        for ( var i = 0; i < ops.length; i++)
          $(element).append(
              "<option value=\"" + ops[i] + "\">" + ops[i]
                  + "</option>");
        $("#record").append("<br/>更新列表成功！<br/>");
      }
    });
    
    
  }
</script>
</head>

<body>
  <div>
    
    <select id="select1" onfocus=getFirstFloorValue(this)>
      <option value="1">点击取值</option>
    </select>
  </div>
  <dir>
    <h3>记录信息：</h3>
    <span id="record"></span>
  </dir>
</body>
</html>

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JAVA servlet code:

package servlet;

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;
import net.sf.json.JSONArray;

public class ValueGetController extends HttpServlet {
  
  private static final long serialVersionUID = -1293610555518403602L;


  /**
   * Constructor of the object.
   */
  public ValueGetController() {
    super();
  }

  /**
   * Destruction of the servlet. <br>
   */
  public void destroy() {
    super.destroy(); // Just puts "destroy" string in log
    // Put your code here
  }

  /**
   * The doGet method of the servlet. <br>
   *
   * This method is called when a form has its tag value method equals to get.
   * 
   * @param request the request send by the client to the server
   * @param response the response send by the server to the client
   * @throws ServletException if an error occurred
   * @throws IOException if an error occurred
   */
  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {

    doPost(request, response);
    

  }

  /**
   * The doPost method of the servlet. <br>
   *
   * This method is called when a form has its tag value method equals to post.
   * 
   * @param request the request send by the client to the server
   * @param response the response send by the server to the client
   * @throws ServletException if an error occurred
   * @throws IOException if an error occurred
   */
  public void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {

    request.setCharacterEncoding("GBK");
     response.setContentType("text/html;charset=gbk");
     PrintWriter out = response.getWriter();
     String action = request.getParameter("action");
     System.out.println("action"+action);
     if (action.equals("GetFirstFloorValue")) {
             String[] str = GetFirstFloorValue();
             JSONArray ja = JSONArray.fromObject(str);
             String json = ja.toString();
              out.print(json);
             System.out.println(json);
             out.flush();
              out.close();
              return;
           }
            out.flush();
            out.close();
  }

  private String[] GetFirstFloorValue() {
     String[] str = new String[4];
         str[0] = "test1";
         str[1] = "test2";
         str[2] = "test3";
         str[3] = "test4";
         return str;

  }

  

}

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About the web.xml configuration of servlet:

<&#63;xml version="1.0" encoding="UTF-8"&#63;>
<web-app version="2.5" 
  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_2_5.xsd">
 <servlet>
  <description>This is the description of my J2EE component</description>
  <display-name>This is the display name of my J2EE component</display-name>
  <servlet-name>ValueGetController</servlet-name>
  <servlet-class>servlet.ValueGetController</servlet-class>
 </servlet>

 <servlet-mapping>
  <servlet-name>ValueGetController</servlet-name>
  <url-pattern>/ValueGetController</url-pattern>
 </servlet-mapping>
 
 
  
 <welcome-file-list>
  <welcome-file>index.jsp</welcome-file>
 </welcome-file-list>
</web-app>

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