jsp界面
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <!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=utf-8"> <title>Insert title here</title> <script type="text/javascript"> function loadProvince() { var req = new XMLHttpRequest(); req.onreadystatechange = function() { if (req.readyState == 4) { var data = req.responseText; var myObj = eval("(" + data + ")"); //eval函数：格式化函数--将字符串转化为javascript对象的函数 for (var i = 0; i < myObj.length; i++) { var oneProvince = myObj[i]; var opKey = oneProvince.split("-")[0]; var opValue = oneProvince.split("-")[1]; //找到province对应的下拉框 var proSelectObj = document.getElementById("proId"); var newOption = document.createElement("OPTION"); newOption.value = opKey; newOption.innerHTML = opValue; proSelectObj.appendChild(newOption); } //执行一次加载城市 loadCity(); } }; req.open("post", "pa", true); req.send(null); } function loadCity() { var proSelectObj = document.getElementById("proId"); //获取到当前选中的省份，并用于数据库查询 var proIdToDB = proSelectObj[proSelectObj.selectedIndex].value; var req = new XMLHttpRequest(); req.onreadystatechange = function() { if (req.readyState == 4) { var data = req.responseText; var myObj = eval("(" + data + ")"); var citySelectObj = document.getElementById("cityId"); //清理原来的城市信息 while (citySelectObj.childNodes.length > 0) { citySelectObj.removeChild(citySelectObj.lastChild); } for (var i = 0; i < myObj.length; i++) { var oneCity = myObj[i]; var cityKey = oneCity.split("-")[0]; var cityValue = oneCity.split("-")[1]; var newOption = document.createElement("OPTION"); newOption.value = cityKey; newOption.innerHTML = cityValue; citySelectObj.appendChild(newOption); } } }; req.open("post", "ca", true); req.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); req.send("proId=" + proIdToDB); } </script> </head> <body onload="loadProvince()"> <!-- 当页面加载完毕时执行 --> 省： <select id="proId" onchange="loadCity()"> <!-- 选项option变更的时候触发事件 --> </select> 城市： <select id="cityId"> </select> </body> </html>
serverlet 获取地市数据
package com.shxt.lesson15.servlets; import java.io.IOException; import java.io.PrintWriter; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; import java.util.ArrayList; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ProvinceAjaxServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //加载省份信息 request.setCharacterEncoding("utf-8"); try { Class.forName("com.mysql.jdbc.Driver"); Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3308/lingyun1", "root", "mysql"); Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery("select * from shxt_province"); ArrayList<String> provinceList = new ArrayList<String>(); while (rs.next()) { String key = rs.getString("PROID"); String value = rs.getString("PRONAME"); provinceList.add(""" + key + "-" + value + """); } response.setContentType("text/html; charset=utf-8"); PrintWriter out = response.getWriter(); System.out.println(provinceList); out.print(provinceList); out.flush(); out.close(); } catch (Exception e) { e.printStackTrace(); } } }
Serverlet 根据地市代码获取城市数据
package com.shxt.lesson15.servlets; import java.io.IOException; import java.io.PrintWriter; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.Statement; import java.util.ArrayList; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class CityAjaxServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); try { String proId = request.getParameter("proId"); String sql = "select * from shxt_city where PROID = '" + proId + "'"; Class.forName("com.mysql.jdbc.Driver"); Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3308/lingyun1", "root", "mysql"); Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery(sql); ArrayList<String> cityList = new ArrayList<String>(); while (rs.next()) { String key = rs.getString("CITYID"); String value = rs.getString("CITYNAME"); cityList.add(""" + key + "-" + value + """); } response.setContentType("text/html; charset=utf-8"); PrintWriter out = response.getWriter(); out.print(cityList); out.flush(); out.close(); } catch (Exception e) { e.printStackTrace(); } } }
小例子
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <!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=utf-8"> <title>Insert title here</title> <!-- ajax 异步交互（javascript和xml的形式） --> <script type="text/javascript"> function validData() { var value1 = document.getElementById("myText1").value; var value2 = document.getElementById("myText2").value; //请求对象 request var req = new XMLHttpRequest(); //创建一个监听函数：监视ajax的各个状态： //1、open状态：servlet（可以接收参数） //2、send发送：发送参数、【重点】需要设置请求头部信息 //3、reciving反馈：servlet开始向页面发送反馈信息 //4、loaded载入：servlet发送的信息全部接收完毕 req.onreadystatechange = function() { if (req.readyState == 1) { //open：准备时间 var mySpan = document.getElementById("showPosition"); mySpan.innerHTML = "<img src='a.jpg' />"; document.getElementById("myBtn").style.display = "none"; } else if (req.readyState == 4) { var data = req.responseText; document.getElementById("myBtn").style.display = "block"; document.getElementById("showPosition").innerHTML = data; } }; //（用post方式）打开myAjax服务应用（Server applet） req.open("post", "myAjax", true); req.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); //发送 req.send("a=" + value1 + "&b=" + value2); } </script> </head> <body> <input id="myText1" /><br /> <input id="myText2" onblur="validData()" /><span id="showPosition"></span><br /> <input /> <input type="button" id="myBtn" value="提交" /> </body> </html>
serverlet
package com.shxt.lesson15.servlets; 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 AjaxServlet extends HttpServlet { /** * Input/Output 字节流（byte的流） * Reader/Writer 字符流（char的流） * InputStreamReader ---- 将input转为reader（byte流变char流） * */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); try { String txt1 = request.getParameter("a"); String txt2 = request.getParameter("b"); System.out.println(txt1 + ", " + txt2); Thread.sleep(5000); //【重点】设置正文类型 -- 页面html response.setContentType("text/html; charset=utf-8"); //servlet向页面发送信息，需要一个response的响应对象 PrintWriter out = response.getWriter(); //Writer流（字符型输出流---向目标写入信息） out.print("返回的信息:发送成功"); out.flush(); //刷新--流中的数据清空 out.close(); //流、关闭 } catch (Exception e) { e.printStackTrace(); } } }