练习二：异常处理之图书查询系统

package com.bookmanage;

public class CommandErrorException extends Exception{

    public CommandErrorException() {

    }

    public CommandErrorException (String message) {
        super(message);
    }
}

package com.bookmanage;

public class BookNotExistException extends Exception {

    public BookNotExistException() {
        // TODO Auto-generated constructor stub
    }

    public BookNotExistException(String message){
        super(message);
    }

}

package com.bookmanage;

public class Books {
    private String name;//图书名称
    private int orderNum;//图书序号

    public Books(String name, int orderNum) {
        // TODO Auto-generated constructor stub
        this.name = name;
        this.orderNum = orderNum;
    }

    public String getName() {
        return name;
    }

    public int getOrderNum() {
        return orderNum;
    }
}

package com.bookmanage;

import java.util.InputMismatchException;
import java.util.Scanner;

public class BookCheck {

    //定义图书数组
    public static Books[] books = { new Books("高等数学", 1), new Books("大学英语", 2),
            new Books("数据结构", 3), new Books("算法导论", 4), new Books("编程基础", 5),
            new Books("线性代数", 6)};

    //定义用于接收控制台输入的变量
    public static Scanner inputScanner = new Scanner(System.in);

    //图书是否查找到的标记变量
    public static boolean flagNotFound = true;

    //判断查找方式
    private static int searchMethod() throws CommandErrorException {
        int methodKey = 0;
        try {
            methodKey = inputScanner.nextInt();//获取输入命令
            if (methodKey==1  methodKey==2) {

            }else {
                throw new CommandErrorException("命令输入错误！");
            }
        } catch (InputMismatchException e) {
            inputScanner = new Scanner(System.in);
            throw new CommandErrorException("命令输入错误！");
        }

        return methodKey;
    }

    //按名称查找图书
    public static int byName(String name) throws BookNotExistException{

        int num = 0;//记录查找到的图书的数组下标
        for (int i = 0; i < books.length; i++) {
            if (name.equals(books[i].getName())) {
                num = i;
                return num;
            }
        }
        throw new BookNotExistException("图书不存在！");      
    }

    //按序号查找图书
    public static int byNum(int orderNum) throws BookNotExistException {
        int num = 0;//记录查找到的图书的数组下标
        for (int i = 0; i < books.length; i++) {
            if (orderNum == books[i].getOrderNum()) {
                num = i;
                return num;
            }
        }
        throw new BookNotExistException("图书不存在！");
    }

    public static void main(String[] args) {

        int bookNumber = 0;
        int methodNumber = 0;
        while (flagNotFound) {
            System.out.println("输入命令：1-按照名称查找图书；2-按照序号查找图书");
            try {
                methodNumber = searchMethod();
                if (methodNumber==1) {
                    System.out.println("输入图书名称：");
                    try {
                        bookNumber = byName(inputScanner.next());
                        flagNotFound = false;
                        System.out.println("book:"+"["+books[bookNumber].getOrderNum()+"] "+books[bookNumber].getName());
                    } catch (BookNotExistException e) {
                        System.out.println("图书不存在！");
                        flagNotFound = true;
                    }
                }else if (methodNumber == 2) {
                    System.out.println("输入图书序号：");
                    try {
                        bookNumber = byNum(inputScanner.nextInt());
                        flagNotFound = false;
                        System.out.println("book:"+"["+books[bookNumber].getOrderNum()+"] "+books[bookNumber].getName());
                    } catch (BookNotExistException e) {
                        System.out.println("图书不存在！");
                        flagNotFound = true;
                    }
                }
            } catch (CommandErrorException e) {
                System.out.println("命令输入错误！请根据提示数字输入命令！");
                flagNotFound = true;
            }
        }
        inputScanner.close();
    }
}