a（+；-；*；/）b-----demo----bai

最新推荐文章于 2025-08-06 16:53:09 发布

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最新推荐文章于 2025-08-06 16:53:09 发布

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CC 4.0 BY-SA版权

文章标签： json java javascript ViewUI

原文链接：http://www.cnblogs.com/ipetergo/p/6261965.html

本文介绍了一个简单的Web计算器应用，使用Java和JSP实现基本的数学运算功能，并通过Ajax进行前后端交互。

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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 = "/";
		}
	}
	
}

转载于:https://www.cnblogs.com/ipetergo/p/6261965.html