员工管理系统（集合与IO流的结合使用 beta5.0 BufferedReader/ BufferedWriter）

 package cn.gee;

 public class Emp {
     private String id;//员工编号  一般是唯一的
     private String sname;
     private int age;
     private float  salary;

     public Emp(){

     }

     public Emp(String id, String sname, int age, float salary) {
         super();
         this.id = id;
         this.sname = sname;
         this.age = age;
         this.salary = salary;
     }

     @Override
     public String toString() {
         return id+","+sname+","+ age + "," + salary;
     }

     public String getId() {
         return id;
     }
     public void setId(String id) {
         this.id = id;
     }
     public String getSname() {
         return sname;
     }
     public void setSname(String sname) {
         this.sname = sname;
     }
     public int getAge() {
         return age;
     }
     public void setAge(int age) {
         this.age = age;
     }
     public float getSalary() {
         return salary;
     }
     public void setSalary(float salary) {
         this.salary = salary;
     }

 }

Emp.java

 package cn.gee;

 import java.io.BufferedReader;
 import java.io.BufferedWriter;
 import java.io.FileNotFoundException;
 import java.io.FileReader;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.util.LinkedList;
 import java.util.List;

 /**
  * 1.每个员工信息 一条一条 写到文件中
  * 2.把多个员工（集合）一起写进去或者读出来
  * @author y
  *
  */
 public class EmpBussiness {
     List<Emp> emps=new LinkedList<Emp>();

     public EmpBussiness() throws IOException{
         init();
     }
     private void init() throws IOException{
         read();
     }
     //获得已有的员工信息
     private  void read() throws IOException{
         FileReader fr=new FileReader("C:\\zhougb\\08\\08\\08\\emps.txt");
         BufferedReader br=new BufferedReader(fr);
         String empStr=null;
         while((empStr=br.readLine())!=null){
             String[] empStrs=empStr.split(",");
             emps.add(new Emp(empStrs[0],empStrs[1],Integer.parseInt(empStrs[2]),Float.parseFloat(empStrs[3])));
         }
         fr.close();
         br.close();
     }

     public void write() throws IOException{
         FileWriter fw=new FileWriter("C:\\zhougb\\08\\08\\08\\emps.txt");
         BufferedWriter bw=new BufferedWriter(fw);
         for(Emp e:emps){
             bw.write(e.toString());
             bw.newLine();
         }
         bw.flush();
         fw.close();
         bw.close();
     }

     //添加员工
     public void add(Emp emp) throws IOException{
 //        read();
         emps.add(emp);
         write();

     }

     //查询所有员工
     public List<Emp> selectAll() throws IOException{
         //read();
         return emps;
     }

     //查询单个员工
     public Emp select(String id){

         for(Emp e:emps){
             System.out.println("EmpBussiness.select()"+e.getId());
             if(id.equals(e.getId())){
                 return e;
             }
         }
         return  null;
     }
     //删除单个员工
         public boolean  delete(String id) throws IOException{

             for(Emp e:emps){
                 if(id.equals(e.getId())){
                     emps.remove(e);
                     write();
                     return  true;
                 }
             }

             return false;
         }

         /**修改员工:
          * 1.不论属性有没有值，都覆盖旧的数据
          * 2.如果属性没有值，那么旧的数据就不覆盖
          * @param nemp
          * @return
          */
         public boolean  update(Emp nemp){
             boolean ret=false;
             for(Emp e:emps){
                 if(nemp.getId().equals(e.getId())){
                     e.setAge(nemp.getAge());
                     e.setSalary(nemp.getSalary());
                     e.setSname(nemp.getSname());
                     ret= true;
                 }
             }
             return ret;
         }
 }

EmpBussiness.java

 package cn.gee;

 import java.io.IOException;
 import java.util.List;
 import java.util.Random;
 import java.util.Scanner;

 public class View {
     public static void main(String[] args) throws IOException {
         EmpBussiness empBussiness=new EmpBussiness();
         System.out.println("------------------------------员工管理系统beta1.0--------------------------");
         System.out.println("1:添加员工 2:查询员工 3:删除员工 4:修改员工 5:所有员工 6:退出系统");
         Scanner sc=new Scanner(System.in);
         int choice=sc.nextInt();
         while(choice<6){
             switch (choice) {
             case 1:
                 System.out.println("请输入名称:");
                 String sname=sc.next();
                 System.out.println("请输入年龄:");
                 int age=sc.nextInt();
                 System.out.println("请输入薪资:");
                 float salary=sc.nextFloat();
                 empBussiness.add(new Emp(Math.round(Math.random()*10000)+"",sname,age,salary));
                 System.out.println("添加成功~");
                 break;
             case 2:
                 System.out.println("请输入编号:");
                 String id=sc.next();
                 System.out.println("员工编号      员工姓名      员工年龄      员工薪资");
                 System.out.println(doShow(empBussiness.select(id)));
                 break;
             case 3:
                 System.out.println("请输入编号:");
                 String did=sc.next();
                 empBussiness.delete(did);
                 System.out.println("删除成功~");
                 break;
             case 4:
                 //empBussiness.delete(sc.next());
                 break;
             case 5:
                 System.out.println("员工编号      员工姓名      员工年龄      员工薪资");
                 StringBuilder sb=new StringBuilder();
                 List<Emp> emps=empBussiness.selectAll();
                 for(Emp e:emps){
                     sb.append(doShow(e));
                 }

                 System.out.println(sb);
                 break;
             case 6:
                 return ;

             }
             choice=sc.nextInt();
         }

     }

     private static  String doShow(Emp e){
         StringBuilder sb=new StringBuilder();
         sb.append(e.getId()+"      ");
         sb.append(e.getSname()+"      ");
         sb.append(e.getAge()+"      ");
         sb.append(e.getSalary()+"      ");
         sb.append("\n");
         return sb.toString();
     }

 }

View.java