页面：
<%@ 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 'index.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" src="js/jquery.js">
</script>
<script>
$(document).ready(
function()
{
//1 按钮关联事件
$("#btn").click(
function ()
{
//构造ajax参数
var paras = "a="+$("#a").val()+"&b="
+$("#b").val()+"&op="+$("#op").val();
//发起ajax请求
$.ajax(
{
type:"get",
url:"CalculatorServlet",
data:paras,
dataType:"json",
cache:false,
success:function(c)
{
var info = "";
//使用增强for，遍历json对象的所有属性
if(c.a!=undefined)
{
alert(c.a+c.show_op+c.b+"="+c.result)
}
else
{
alert("错误编号:"+c.errcode+",错误信息:"+c.errmsg);
}
}
}
);
}
);
}
);
</script>
<body>
请输入a值:<input id="a" value="1"/>
<select id="op">
<option value="add">+</option>
<option value="sub">-</option>
<option value="multi">*</option>
<option value="div">/</option>
</select>
请输入b值:<input id="b" value="2"/>
<input id="btn" type="button" value="获得结果"/>
</body>
</html>
控制器：
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 com.google.gson.Gson;
public class CalculatorServlet extends HttpServlet {
/**
* Constructor of the object.
*/
public CalculatorServlet() {
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 {
//1 中文处理
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
Gson gson = new Gson();
//2 读取入参
int a = -1;
int b = -1;
try {
a = Integer.parseInt(request.getParameter("a"));
b = Integer.parseInt(request.getParameter("b"));
} catch (Exception e)
{
//创建1个错误消息对象，用json写回。方法提前终止。
Msg m = new Msg(1, "输入的数字格式有误！");
String json = gson.toJson(m);
response.getWriter().print(json);
response.getWriter().flush();
response.getWriter().close();
return;
}
String op = request.getParameter("op");
//3 创建calculator对象
Calculator c = new Calculator(a, b, op);
c.cal();//执行计算，算出结果
//4 转成json字符串返回
String json = gson.toJson(c);
response.getWriter().print(json);
response.getWriter().flush();
response.getWriter().close();
}
/**
* 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 {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out
.println("<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print(" This is ");
out.print(this.getClass());
out.println(", using the POST method");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}
//用于提示错误信息的类
public class Msg
{
private int errcode;
private String errmsg;
public int getErrcode() {
return errcode;
}
public void setErrcode(int errcode) {
this.errcode = errcode;
}
public Msg(int errcode, String errMsg) {
super();
this.errcode = errcode;
errmsg = errMsg;
}
}
public class Calculator
{
private int a;
private String op;
private int b;
private String show_op;
private int result;
public Calculator(int a, int b, String op) {
super();
this.a = a;
this.b = b;
this.op = op;
}
public String getOp() {
return op;
}
public void setOp(String op) {
this.op = op;
}
public int getResult() {
return result;
}
public void setResult(int result) {
this.result = result;
}
//执行计算，算出result
public void cal()
{
if("add".equals(op))
{
result = a+b;
show_op = "+";
}
else if("sub".equals(op))
{
result = a-b;
show_op = "-";
}
else if("multi".equals(op))
{
result = a*b;
show_op = "*";
}
else if("div".equals(op))
{
result = a/b;
show_op = "/";
}
}
}