结对作业

package com.edu;

public class Command {
    public Command() {
    }

    public static float opt(String s) throws Exception {
        if(s != null && !"".equals(s.trim())) {
            int a1 = s.indexOf("+");
            int a2 = s.indexOf("-");
            int a3 = s.indexOf("*");
            int a4 = s.indexOf("/");
            int a5 = s.indexOf("(");
            if(a1 == -1 && a2 == -1 && a3 == -1 && a4 == -1) {
                if(s.trim() != null && !"".equals(s.trim())) {
                    return Float.parseFloat(s.trim());
                } else {
                    throw new Exception("operate error");
                }
            } else {
                float n2;
                if(a5 != -1) {
                    int n11 = s.indexOf(")");
                    if(n11 == -1) {
                        throw new Exception("括号不匹配");
                    } else {
                        n2 = opt(s.substring(a5 + 1, n11).trim());
                        s = s.replace(s.substring(a5, n11 + 1), String.valueOf(n2));
                        return opt(s);
                    }
                } else {
                    float n1;
                    if(a1 != -1) {
                        n1 = opt(s.substring(0, a1));
                        n2 = opt(s.substring(a1 + 1, s.length()));
                        return n1 + n2;
                    } else if(a2 != -1) {
                        n1 = opt(s.substring(0, a2));
                        n2 = opt(s.substring(a2 + 1, s.length()));
                        return n1 - n2;
                    } else if(a3 != -1) {
                        n1 = opt(s.substring(0, a3));
                        n2 = opt(s.substring(a3 + 1, s.length()));
                        return n1 * n2;
                    } else if(a4 != -1) {
                        n1 = opt(s.substring(0, a4));
                        n2 = opt(s.substring(a4 + 1, s.length()));
                        return n1 / n2;
                    } else {
                        return (float)Integer.parseInt(s.trim());
                    }
                }
            }
        } else {
            return 0.0F;
        }
    }
}

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

    public class Command {
        public static ArrayList<String> fu= new ArrayList();
        public static ArrayList<Integer> num=  new ArrayList();
        public static ArrayList<String> fg= new ArrayList();
        public static ArrayList<Float> jian= new ArrayList();//保存四则运算中间结果
        public static boolean flag=false;
        public static int n=1;//题目数
        public static int nops=1;//符号数
    public static int mlow=0;//数值最低取值范围
    public static int mhigh=50;//数值最高取值范围
    public static int c=0;//是否含有括号
    public static int bc=0;//是否包含乘除法
    /**获取表达式
     * @return
     */
    public static String fun() {
        String str="";
        int k=0,s=0,nos=(int) (Math.random()*nops)+1;
        int a=(int) (Math.random()*((mhigh-mlow)/n))+mlow;
        num.set(0, a);
        str+= a;
        for(int i=0;i<nops;i++) {
            char f=fu.get((int) (Math.random()*fu.size())).charAt(0);
            if(f==‘/‘) {
                str+= f;
                fg.set(i, f+"");
                int b= getYin(num.get(i));
                num.set(i+1, b);
                str+= b;
            }else if(f==‘*‘){
                str+= f;
                fg.set(i, f+"");
                int b=(int) (((mhigh-mlow)/(num.get(i)/2+1))*Math.random()+mlow);
                num.set(i+1, b);
                str+= b;
            }else if(i>1&&fg.get(i-1).equals("+")) {
                str+=‘-‘;
                fg.set(i, f+"");
                int b=(int) (((mhigh-mlow)/(num.get(i)+1))*Math.random()+mlow);
                num.set(i+1, b);
                if(bc==1&&k==0&&nops>2&&s<2&&i<num.size()-2) {
                    str+="("+b;
                    k=1;
                    s++;
                }else if(bc==1&&k==1&&nops>2) {
                    str+=b+")";
                    k=0;
                }else {
                    str+= b;
                }
            }else  {
                str+= f;
                fg.set(i, f+"");
                int b=(int)(Math.random()*((mhigh-mlow)))+mlow;
                num.set(i+1, b);
                if(bc==1&&k==0&&nops>2&&s<2&&i<num.size()-2) {
                    str+="("+b;
                    k=1;
                    s++;
                }else if(bc==1&&k==1&&nops>2) {
                    str+=b+")";
                    k=0;
                }else {
                    str+= b;
                }
            }
        }
        if(bc==1&&k==1) {
            str+=")";
        }
        return str;
    }

<%@ 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=ISO-8859-1">
<title>四则运算</title>
</head>
<body>
<h1>文件上传</h1>
<form method="post" action="uploadServlet" enctype="multipart/form-data">
    选择一个文件:
    <input type="file" name="uploadFile" />
    <br/><br/>
    <input type="submit" value="上传" />
</form>
</body>
</html>