员工管理系统（集合与IO流的结合使用 beta2.0 ObjectInputStream/ ObjectOutputStream）

package cn.employee;

import java.io.Serializable;

public class Employee implements Serializable{
    private static final long serialVersionUID = 1L;
    private int empNo;
    private String name;
    private String department;

    public Employee() {
        super();
    }

    public Employee(int empNo, String name, String department) {
        super();
        this.empNo = empNo;
        this.name = name;
        this.department = department;
    }

    public int getEmpNo() {
        return empNo;
    }

    public void setEmpNo(int empNo) {
        this.empNo = empNo;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDepartment() {
        return department;
    }

    public void setDepartment(String department) {
        this.department = department;
    }

    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result
                + ((department == null) ? 0 : department.hashCode());
        result = prime * result + empNo;
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        return result;
    }

    public String toString() {
        return "Employee [empNo=" + empNo + ", name=" + name + ", department="
                + department + "]";
    }

}

package cn.employee;

import java.util.List;

public class EmpUtils {
    
    /**
     * 是否有相同的员工编号
     */
    public static boolean copy(List<Employee> list,int empNo){
        boolean flag = false;
        for (int i = 0; i < list.size(); i++) {
            if(list.get(i).getEmpNo()==empNo){
                flag=true;
                break;
            }            
        }
        return flag;
    }
    
    /**
     * 添加员工
     */
    public static boolean add(List<Employee> list, Employee e) {
        if (list.contains(e)) {
            System.out.println("有重复的员工");
            return false;
        } 
        return list.add(e);
    }

    /**
     * 查询所有员工
     */
    public static void querys(List<Employee> list) {
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i));
        }
    }

    /**
     * 查询指定员工
     */
    public static void query(List<Employee> list,int empNo){
        for(int i=0;i<list.size();i++){
            if(list.get(i).getEmpNo()==empNo){
                System.out.println(list.get(i));
                break;
            }
            if((i==list.size()-1)&&list.get(i).getEmpNo()!=empNo){
                System.out.println("不存在该员工！");
            }
        }    
    }
    /**
     * 删除员工
     */
    public static void delete(List<Employee> list,int empNo){
        for(int i=0;i<list.size();i++){
            if(list.get(i).getEmpNo()==empNo){
                list.remove(list.get(i));                
                System.out.println("删除成功！");
                break;
            }
            if((i==list.size()-1)&&list.get(i).getEmpNo()!=empNo){
                System.out.println("删除失败！");
            }
        }
    }
    /**
     * 修改员工
     */
    public static void update(List<Employee> list,int empNo,String name,String department){
        for (Employee e : list) {
            if(e.getEmpNo()==empNo){
                e.setName(name); 
                e.setDepartment(department);
                System.out.println("修改成功！");
                break;
            }
        }
    }
}

package cn.employee;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class MyEmployee {
    Scanner sc = new Scanner(System.in);
    List<Employee> list = null;
    int empNo;
    String name;
    String department;
    int num = 0;
    boolean flag = false;
    File file = null;
    FileOutputStream fos=null;
    ObjectInputStream ois = null;
    ObjectOutputStream oos = null;

    public MyEmployee() throws FileNotFoundException, IOException,
            ClassNotFoundException {
        list = new ArrayList<Employee>();
        fun(list);
    }

    public void fun(List<Employee> list) throws FileNotFoundException,
            IOException, ClassNotFoundException {
        ok: for (;;) {
            printOptions();
            num = sc.nextInt();

            if (num < 1 || num > 6) {
                System.out.println("输入有误，将重新开始选择！");
                break ok;
            }

            switch (num) {
            case 1:
                printEmpNo();
                if (!EmpUtils.copy(list, empNo)) {
                    printName();
                    if (EmpUtils.add(list,
                            new Employee(empNo, name, department))) {
                        addObject(list);//
                        System.out.println("添加成功！");
                    }
                } else {
                    System.out.println("添加失败！");
                }
                break;
            case 2:
                // EmpUtils.querys(list);
                list=queryAllObject();
//                System.out.println(list); 
                break;
            case 3: 
//                System.out.println("3333   "+list); 
                printEmpNo();
                EmpUtils.query(list, empNo);
                break;
            case 4:
                printEmpNo();
                EmpUtils.delete(list, empNo);
//                System.out.println(list); 
                addObject(list);
                break;
            case 5:
                printEmpNo();
                if (EmpUtils.copy(list, empNo)) {// 有该员工
                    printName();
                    EmpUtils.update(list, empNo, name, department);
                }
                addObject(list);
                break;
            case 6:
                flag = true;
            }

            if (flag) {// 退出
                break;
            }
        }
    }

    public void printOptions() {
        System.out.println("***员工管理系统***");
        System.out.println("1.添加员工");
        System.out.println("2.查询所有员工");
        System.out.println("3.查询员工");
        System.out.println("4.删除员工");
        System.out.println("5.修改员工");
        System.out.println("6.退出");
        System.out.println("请输入你要进行的操作：");
    }

    public void printEmpNo() {
        System.out.println("请输入员工编号：");
        empNo = sc.nextInt();
    }

    public void printName() {
        System.out.println("请输入员工姓名：");
        name = sc.next();
        System.out.println("请输入员工部门：");
        department = sc.next();
    }

    /**
     * 在向一个文件写入可序列化对象时，每次只想向文件的末尾添加一个可序列化的对象，于是使用了FileOutputStream（文件名，true）
     * 间接的构建了ObjectOutputStream流对象
     * ，在向外读数据的时候第一次运行的时候不会报错，在第二次就会报java.io.StreamCorruptedException: invalid
     * type code: AC错误
     * 
     * 在一个文件都有一个文件的头部和文件体。由于对多次使用FileOutputStream（文件名，true）
     * 构建的ObjectOutputStream对象向同一个文件写数据
     * ，在每次些数据的时候他都会向这个文件末尾先写入header在写入你要写的对象数据，在读取的时候遇到这个在文件体中的header就会报错
     * 。导致读出时，出现streamcorrput异常。
     * 
     * 解决办法：所以这里要判断是不是第一次写文件，若是则写入头部，否则不写入。
     * 
     * @param list
     * @throws FileNotFoundException
     * @throws IOException
     */
    public void addObject(List<Employee> list) throws FileNotFoundException, IOException {
        file = new File("src/cn/employee/emp.txt");
//        fos=new FileOutputStream(file,true);
        fos=new FileOutputStream(file);
        if (file.length() < 1) {// 判断文件大小并调用不同的方法
            oos = new ObjectOutputStream(fos);
        } else {
            oos = new MyObjectOutputStream(fos);
        }
        oos.writeObject(list);
        oos.flush();
        oos.close();
    }

    @SuppressWarnings("unchecked")
    public List<Employee> queryAllObject() throws FileNotFoundException, IOException,
            ClassNotFoundException {
        ois = new ObjectInputStream(new FileInputStream(
                "src/cn/employee/emp.txt"));
        List<Employee> list2=new ArrayList<Employee>();
        list2 = (ArrayList<Employee>) ois.readObject();

        for (int i = 0; i < list2.size(); i++) {
            System.out.println(list2.get(i));
        }

        ois.close();
        return list2;
    }
}

/*class MyObjectOutputStream extends ObjectOutputStream {
    public MyObjectOutputStream() throws IOException {
        super();
    }

    public MyObjectOutputStream(OutputStream out) throws IOException {
        super(out);
    }

    @Override
    protected void writeStreamHeader() throws IOException {
        return;
    }
}*/

package cn.employee;

import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.OutputStream;

public class MyObjectOutputStream extends ObjectOutputStream {
    public MyObjectOutputStream() throws IOException {
        super();
    }

    public MyObjectOutputStream(OutputStream out) throws IOException {
        super(out);
    }

    @Override
    protected void writeStreamHeader() throws IOException {
        return;
    }
}

package cn.employee;

import java.io.FileNotFoundException;
import java.io.IOException;

/**
 * 员工管理系统
 * @author 王恒
 * @time 2016年10月19日 下午8:54:14
 */
public class TestEmp {

    @SuppressWarnings("unused")
    public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException,NullPointerException {
        
        MyEmployee a=new MyEmployee();
        
    }
}