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 + "]";
     }

 }

Employee

 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;
             }
         }
     }
 }

EmpUtils

 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;
     }
 }*/

MyEmployee

 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;
     }
 }

MyObjectOutputStream

 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();

     }
 }

TestEmp