利用ajax获得后台传过来的json,前端无法解析,对前端不是很深入,求指导-问答-阿里云开发者社区-阿里云

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利用ajax获得后台传过来的json,前端无法解析,对前端不是很深入,求指导

杨冬芳 2016-07-07 14:22:03 2069

这是servlet:
package com.kj.servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import net.sf.json.JSONArray;

import com.kj.entity.User;
import com.kj.service.IUserService;
import com.kj.service.impl.UserServiceImpl;

public class MainPageServlet extends HttpServlet{
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JSON 前端开发 数据格式
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  • 问问小秘
    2019-10-17 11:48:56
    一般都是后台直接拼接好JSON格式返回,页面解析。 给你看个例子: <%@ page language="java" contentType="text/html; charset=GB18030"  pageEncoding="GB18030"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" " http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=GB18030"> <title>四级联动下拉列表选中值保持不变</title> <style type="text/css">  div #tip {  font:consolas normal 20px;  color:blue;  } </style> <script type="text/javascript" src="js/jquery-1.4.4.min.js"></script> <script type="text/javascript">  $(function() {  $("#province").change(function() {  if ($("#province").val() == '0') {  $("#city").html('');  $("#county").html('');  $("#town").html('');  return;  }  $("#tip").append("<span>请求Ajax获取城市...<br></span>");  $.get("ajax.do",  {type:'1',  value:$("#province").val(),  time:new Date()  },function(data) {  $("#tip").append("<span>"+$("#province").val()+"下城市信息获取成功<br></span>");  $("#city").html('<option value="0" selected="selected">请选择一个市</option>');  var pros = eval(data);  for (var i=0;i<pros.length;i++) {  var cityName = pros[i].name;  var cityValue = pros[i].value;  var opt = $("<option value='" + cityValue + "'>"+cityName+"</option>");  $("#city").append(opt);  }  });  });  $("#city").change(function() {  $("#tip").append("<span>请求Ajax获取县...<br></span>");  if ($("#city").val() == '0') {  $("#county").html('');  $("#town").html('');  return;  }  $.get("ajax.do",  {type:'2',  value:$("#city").val(),  time:new Date()  },function(data) {  $("#tip").append("<span>"+$("#city").val()+"下县的信息获取成功<br></span>");  $("#county").html('<option value="0" selected="selected">请选择一个县</option>');  var pros = eval(data);  for (var i=0;i<pros.length;i++) {  var countyName = pros[i].name;  var countyValue = pros[i].value;  var opt = $("<option value='" + countyValue + "'>"+countyName+"</option>");  $("#county").append(opt);  }  });  });  $("#county").change(function() {  $("#tip").append("<span>请求Ajax获取镇...<br></span>");  if ($("#county").val() == '0') {  $("#town").html('');  return;  }  $.get("ajax.do",  {type:'3',  value:$("#county").val(),  time:new Date()  },function(data) {  $("#tip").append("<span>"+$("#county").val()+"下镇的信息获取成功<br></span>");  $("#town").html('');  var pros = eval(data);  for (var i=0;i<pros.length;i++) {  var townName = pros[i].name;  var townValue = pros[i].value;  var opt = $("<option value='" + townValue + "'>"+townName+"</option>");  $("#town").append(opt);  }  });  });  }); </script> </head> <body>  省:<select id="province">  <option value="0" selected="selected">请选择一个省</option>  <option value="hubei">湖北</option>  </select>  市:<select id="city"></select>  县:<select id="county"></select>  镇:<select id="town"></select>   <div id="tip"></div> </body> </html>  package com.servlet.ajax; import java.io.IOException;import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;  /**  * Servlet implementation class AjaxServlet  */ @WebServlet("/ajax.do") public class AjaxServlet extends HttpServlet {  private static final long serialVersionUID = 1L;  /**  * Default constructor.  */  public AjaxServlet() {  // TODO Auto-generated constructor stub  }  /**  * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)  */  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  this.doPost(request, response);  }  /**  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)  */  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  response.setContentType("text/html;charset=utf-8");  String type = request.getParameter("type");  String value = request.getParameter("value");  PrintWriter pw = response.getWriter();  System.out.println(type);   if ("1".equals(type) && value != null && !"".equals(value)) { // 根据省获取市  // 这里可以从数据库获取  if ("hubei".equals(value)) {  StringBuilder citys = new StringBuilder();  citys.append("[");  citys.append("{name:'武汉',value:'hubei001'},");  citys.append("{name:'襄阳',value:'hubei002'}");  citys.append("]");  System.out.println(citys.toString());  pw.print(citys.toString());  }  }  else if ("2".equals(type) && value != null && !"".equals(value)) { // 根据省获取县  // 这里可以从数据库获取  StringBuilder countries = new StringBuilder();  if ("hubei001".equals(value)) {  countries.append("[");  countries.append("{name:'AAA县',value:'wuhan001'},");  countries.append("{name:'BBB县',value:'wuhan002'},");  countries.append("{name:'CCC县',value:'wuhan003'}");  countries.append("]");  }  else if ("hubei002".equals(value)) {  countries.append("[");  countries.append("{name:'南漳县',value:'xiangyang001'},");  countries.append("{name:'古城县',value:'xiangyang002'}");  countries.append("]");  }   System.out.println(countries.toString());  pw.print(countries.toString());  }  else if ("3".equals(type) && value != null && !"".equals(value)) {  StringBuilder towns = new StringBuilder();  if ("wuhan001".equals(value)) {  towns.append("[");  towns.append("{name:'AAA镇',value:'wuhan001'},");  towns.append("{name:'BBB镇',value:'wuhan002'},");  towns.append("{name:'CCC镇',value:'wuhan003'}");  towns.append("]");   }  else if ("wuhan002".equals(value)) {  towns.append("[");  towns.append("{name:'CCC镇',value:'wuhan001'},");  towns.append("{name:'DDD镇',value:'wuhan002'},");  towns.append("{name:'EEE镇',value:'wuhan003'}");  towns.append("]");  }  else if ("wuhan003".equals(value)) {  towns.append("[");  towns.append("{name:'FFF镇',value:'wuhan001'},");  towns.append("{name:'GGG镇',value:'wuhan002'}");  towns.append("]");  }  else if ("xiangyang001".equals(value)) {  towns.append("[");  towns.append("{name:'WWW镇',value:'wuhan001'},");  towns.append("{name:'RRR镇',value:'wuhan002'}");  towns.append("]");  }  else if ("xiangyang002".equals(value)) {  towns.append("[");  towns.append("{name:'XXX镇',value:'wuhan001'},");  towns.append("{name:'YYY镇',value:'wuhan002'}");  towns.append("]");  }   System.out.println(towns.toString());  pw.print(towns.toString());  }  }  }
    

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