13 springboot项目——准备数据和dao类

13.1 静态资源下载

https://download.csdn.net/download/no996yes885/88151513

13.2 静态资源位置

        css样式文件放在static的css目录下；static的img下放图片；template目录下放其余的html文件。 

        

13.3 创建两个实体类

        导入依赖：lombok

<!--lombok-->
<dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId>
</dependency>

        加入@Data注解：自动创建set、get等方法；

        加入@AllArgsConstructor注解：自动创建有参构造方法；

        加入NoArgsConstructor注解：自动创建无参构造方法；

         Department：

package jiang.com.springbootstudy.pojo;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;@Data
@AllArgsConstructor
@NoArgsConstructor
public class Department {private  Integer id;private String departmentName;
}

        Employee：

package jiang.com.springbootstudy.pojo;
import lombok.Data;
import lombok.NoArgsConstructor;import java.util.Date;@Data
@NoArgsConstructor
public class Employee {private Integer id;private String lastName;private  String email;private Integer gender; // 0 女  1 男private  Department department;private Date birth;public Employee(Integer id, String lastName, String email, Integer gender, Department department) {this.id = id;this.lastName = lastName;this.email = email;this.gender = gender;this.department = department;this.birth = new Date();  // 一创建对象调用有参的话，自动生成了日期属性}
}

13.4 创建实体类对应的dao类

        DepartmentDao：

        注意，这里类中的加载顺序，静态的属性和代码要先加载，然后再加载其他的。使用静态代码块结合Map来模拟数据库，数据库的删查使用的是remove、values、get方法。

package jiang.com.springbootstudy.dao;import jiang.com.springbootstudy.pojo.Department;
import lombok.Data;
import org.springframework.stereotype.Repository;import java.util.Collection;
import java.util.HashMap;
import java.util.Map;
@Data
@Repository
public class DepartmentDao {/*模拟数据库中的数据*/private static Map<Integer, Department> departments = null;static {departments = new HashMap<Integer, Department>();//创建一个部门表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<Department> getDepartments(){return departments.values();}// 通过id得到部门public  Department getDepartmentById(Integer id){return departments.get(id);}
}

         EmployeeDao:

package jiang.com.springbootstudy.dao;import jiang.com.springbootstudy.pojo.Department;
import jiang.com.springbootstudy.pojo.Employee;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;import java.util.Collection;
import java.util.HashMap;
import java.util.Map;@Repository //自动注入需要的注解
public class EmployeeDao {private static Map<Integer, Employee> employees = null;// 员工所属的部门// 放数据，先加载静态的东西，比如说静态的遍历或者静态的代码@Autowired  //自动注入private DepartmentDao departmentDao;static {employees = new HashMap<Integer, Employee>();//前面只是定义了成员变量的类型，并没有赋值，null无法调用put方法，所以要创建对象。employees.put(1001,new Employee(1001,"AA","[e-mail]",0,new Department(101,"教学部")));employees.put(1002,new Employee(1002,"AA","[e-mail]",1,new Department(101,"市场部")));employees.put(1003,new Employee(1003,"AA","[e-mail]",0,new Department(101,"教研部")));employees.put(1004,new Employee(1004,"AA","[e-mail]",1,new Department(101,"运营部")));employees.put(1005,new Employee(1005,"AA","[e-mail]",0,new Department(101,"后勤部")));}// 主键自增private static Integer initId = 1006;  // static和没有有什么区别？// 增加员工public void save(Employee employee){if (employee.getId()==null){employee.setId(initId++);//自增变量的值也会改变}employee.setDepartment(departmentDao.getDepartmentById(employee.getDepartment().getId())); //这句话可以忽略，原理是调用了接口的getDepartmentById方法传入从员工的部门属性获取的部门id得到一个部门，然后把部门属性赋值给了员工employees.put(employee.getId(),employee);}// 查询全部员工信息public Collection<Employee> getAll(){   //集合需要掌握一下return employees.values();}// 通过id查询员工public Employee getEmployeeById(Integer id){return employees.get(id);}// 删除员工public void delete(Integer id){employees.remove(id);}}