传统MVC实例

index.html

<!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>计算器</title>
<script type="text/javascript" src="index.js" charset="gbk"></script>
<script type="text/javascript">
    function checkNum(tag) {
        var value = tag.value;
        var len = value.length;
        for ( var i = 0; i < len; i++) {
            if (value.charAt(i) < '0' || value.charAt(i) > '9') {
                tag.value = "";
                tag.blur();
                tag.focus();
                break;
            }
        }
    }
</script>
</head>
<body>
    <br />
    <h1>算术计算器</h1>
    <form action="#" method="post" id="calcform">
        <table>
            <tbody>
                <tr>
                    <td>第一个参数：</td>
                    <td><input type="text" name="num1" onblur="checkNum(this)" />
                    </td>
                </tr>
                <tr>
                    <td>第二个参数：</td>
                    <td><input type="text" name="num2" onblur="checkNum(this)" />
                    </td>
                </tr>
                <tr>
                    <td>操作</td>
                    <td><input type="button" value="加" onclick="add()" /> <input
                        type="button" value="减" onclick="subtract()" /> <input
                        type="button" value="乘" onclick="multiply()" /> <input
                        type="button" value="除" onclick="divide()" /></td>
                </tr>
            </tbody>
        </table>
    </form>
</body>
</html>

index.js

/**
 * 
 */

function add() {
    with (document.forms['calcform']) {
        action = 'add.action';
        submit();
    }
}
function subtract() {
    with (document.forms['calcform']) {
        action = 'subtract.action';
        submit();
    }
}
function multiply() {
    with (document.forms['calcform']) {
        action = 'multiply.action';
        submit();
    }
}
function divide() {
    with (document.forms['calcform']) {
        action = 'divide.action';
        submit();
    }
}

 Controller.java

package com.wangzhu.servlet;

import java.io.IOException;
import java.util.HashMap;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.wangzhu.action.Action;
import com.wangzhu.action.inter.AddAction;
import com.wangzhu.action.inter.DivideAction;
import com.wangzhu.action.inter.MultiplyAction;
import com.wangzhu.action.inter.SubtractAction;

/**
 * Servlet implementation class Controller
 */
@WebServlet("/Controller")
public class Controller extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private HashMap<String, Action> actionMap;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public Controller() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see Servlet#init(ServletConfig)
     */
    public void init(ServletConfig config) throws ServletException {
        actionMap = new HashMap<String, Action>();
        actionMap.put("add", new AddAction());
        actionMap.put("subtract", new SubtractAction());
        actionMap.put("multiply", new MultiplyAction());
        actionMap.put("divide", new DivideAction());
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        String path = request.getServletPath();
        Action action = determinActionByPath(path);
        String resultView = action.execute(request, response);
        if (null != resultView) {
            request.getRequestDispatcher(resultView).forward(request, response);
        }
    }

    private Action determinActionByPath(String path) {
        String actionName = path.substring(path.lastIndexOf("/") + 1,
                path.length() - 7);
        Action action = actionMap.get(actionName);
        return action;
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
     *      response)
     */
    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }

}

Calculator.java

package com.wangzhu.calc;

public class Calculator {
    public double add(double a, double b) {
        return a + b;
    }

    public double subtract(double a, double b) {
        return a - b;
    }

    public double multiply(double a, double b) {
        return a * b;
    }

    public double divide(double a, double b) {
        return a / b;
    }
}

action.java

package com.wangzhu.action;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public interface Action {
    String execute(HttpServletRequest request, HttpServletResponse response);
}

AddAction.java

package com.wangzhu.action.inter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.wangzhu.action.Action;
import com.wangzhu.calc.Calculator;

public class AddAction implements Action {

    Calculator calc = new Calculator();

    @Override
    public String execute(HttpServletRequest request,
            HttpServletResponse response) {
        String stra = request.getParameter("num1");
        String strb = request.getParameter("num2");
        double numa = 0, numb = 0;
        if (null != stra && null != strb && !"".equals(stra)
                && !"".equals(strb)) {
            numa = Double.parseDouble(stra);
            numb = Double.parseDouble(strb);
        }
        request.setAttribute("result", calc.add(numa, numb));
        request.setAttribute("msg", "+");
        return "result.jsp";
    }

}

SubtractAction.java

package com.wangzhu.action.inter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.wangzhu.action.Action;
import com.wangzhu.calc.Calculator;

public class SubtractAction implements Action {
    Calculator calc = new Calculator();

    @Override
    public String execute(HttpServletRequest request,
            HttpServletResponse response) {
        String stra = request.getParameter("num1");
        String strb = request.getParameter("num2");
        double numa = 0, numb = 0;
        if (null != stra && null != strb && !"".equals(stra)
                && !"".equals(strb)) {
            numa = Double.parseDouble(stra);
            numb = Double.parseDouble(strb);
        }
        request.setAttribute("result", calc.subtract(numa, numb));
        request.setAttribute("msg", "-");
        return "result.jsp";
    }

}

MultiplyAction.java

package com.wangzhu.action.inter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.wangzhu.action.Action;
import com.wangzhu.calc.Calculator;

public class MultiplyAction implements Action {
    Calculator calc = new Calculator();

    @Override
    public String execute(HttpServletRequest request,
            HttpServletResponse response) {
        String stra = request.getParameter("num1");
        String strb = request.getParameter("num2");
        double numa = 0, numb = 0;
        if (null != stra && null != strb && !"".equals(stra)
                && !"".equals(strb)) {
            numa = Double.parseDouble(stra);
            numb = Double.parseDouble(strb);
        }
        request.setAttribute("result", calc.multiply(numa, numb));
        request.setAttribute("msg", "*");
        return "result.jsp";
    }

}

DivideAction.java

package com.wangzhu.action.inter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.wangzhu.action.Action;
import com.wangzhu.calc.Calculator;

public class DivideAction implements Action {
    Calculator calc = new Calculator();

    @Override
    public String execute(HttpServletRequest request,
            HttpServletResponse response) {
        String stra = request.getParameter("num1");
        String strb = request.getParameter("num2");
        double numa = 0, numb = 0;
        if (null != stra && null != strb && !"".equals(stra)
                && !"".equals(strb)) {
            numa = Double.parseDouble(stra);
            numb = Double.parseDouble(strb);
        }
        request.setAttribute("result", calc.divide(numa, numb));

        request.setAttribute("msg", "/");
        return "result.jsp";
    }

}
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原文地址：https://www.cnblogs.com/xiaoxian1369/p/2662988.html