springboot使用HashMap的数据库

@Data相当于类中有get与set方法

@NoArgsConstructor：相当于类中有无参构造器

@AllArgsConstructor：相当于类中有有参构造器

@Repository：使用@Repository注解可以确保DAO或者repositories提供异常转译，这个注解修饰的DAO或者repositories类会被ComponetScan发现并配置，同时也不需要为它们提供XML配置项。

@Autowired：自动导入依赖bean

@Data
@NoArgsConstructor
public class Department {
    private Integer id;
    private String departmentName;
    public Department(Integer id,String departmentName){
        this.id=id;
        this.departmentName=departmentName;
    }
}

@Data
@AllArgsConstructor
@NoArgsConstructor//无参
public class Employee {
    private Integer id;
    private String lastName;
    private String email;
    private int sex;//0表示女，1表示男
    private Department department;
    private Date birth;

    public Employee(Integer id, String lastName, String email, int sex, Department department) {
        this.id = id;
        this.lastName = lastName;
        this.email = email;
        this.sex = sex;
        this.department = department;
        this.birth = new Date();
    }
}

Collection类

//员工Dao
@Repository
public class EmployeeDao {
    private static Map employees=null;
    @Autowired
    private DepartmentDao departmentDao;
    static{
        employees=new HashMap();
        employees.put(1001,new Employee
                (1001,"sheepbotany","A2464018412@qq.com",0,new Department(101,"教学部")));
        employees.put(1002,new Employee
                (1002,"sheep","B2464018412@qq.com",0,new Department(102,"市场部")));
        employees.put(1003,new Employee
                (1003,"botany","C2464018412@qq.com",0,new Department(103,"教研部")));
        employees.put(1004,new Employee
                (1004,"wood","D2464018412@qq.com",1,new Department(104,"运营部")));
        employees.put(1005,new Employee
                (1005,"woodwhale","E2464018412@qq.com",1,new Department(105,"后勤部")));
    }

    //主键自增
    private static Integer initId=1006;
    //增加一个员工
    public void save(Employee employee){
        if(employee.getId()==null){
            employee.setId(initId++);
        }
        employee.setDepartment(departmentDao.getDepartmentById(employee.getDepartment().getId()));
        employees.put(employee.getId(),employee);
    }

    //查询所有的员工信息
    public Collection getAll() {
        return employees.values();
    }
    //通过id查询员工
    public Employee getElementById(Integer id) {
        return employees.get(id);
    }
    //删除员工
    public void delete(Integer id){
        employees.remove(id);
    }
}

@Repository
public class DepartmentDao {

    //模拟数据库中的数据
    private static Map departments=null;

    static{
        //创建一个部门表
        departments=new HashMap();

        departments.put(101,new Department(101,"教学部"));
        departments.put(102,new Department(102,"市场部"));
        departments.put(103,new Department(103,"教研部"));
        departments.put(104,new Department(104,"运营部"));
        departments.put(105,new Department(105,"后勤部"));

    }
    //获得所有部门信息
    public Collection getDepartments() {
        return departments.values();
    }

    //通过id得到部门
    public Department getDepartmentById(Integer id){
        return departments.get(id);

    }
}