模拟数据源 DAO层

package com.zzh.web.dao;

import com.zzh.web.pojo.Department;
import org.springframework.stereotype.Repository;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

@Repository
public class DepartmentDao {

    //模拟数据库的数据
    private static Map<Integer, Department> departments = null;

    static {
        departments = new HashMap<Integer, Department>();

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

    public Collection<Department> getDepartments(){
        return departments.values();
    }

    public Department getDepartmentById(Integer id){
        return departments.get(id);
    }
}

package com.zzh.web.dao;

import com.zzh.web.pojo.Department;
import com.zzh.web.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
public class EmployeeDao {


    //模拟数据库的数据
    private static Map<Integer, Employee> employees = null;

    @Autowired
    private DepartmentDao departmentDao;

    static {
        employees = new HashMap<Integer, Employee>();

        employees.put(1001, new Employee(1001, "AA", "A123@qq.com", 0, new Department(101, "教学部")));
        employees.put(1002, new Employee(1002, "BB", "B123@qq.com", 1, new Department(102, "市场部")));
        employees.put(1003, new Employee(1003, "CC", "C123@qq.com", 0, new Department(103, "运营部")));
        employees.put(1004, new Employee(1004, "DD", "D123@qq.com", 1, new Department(104, "后勤部")));
        employees.put(1005, new Employee(1005, "EE", "E123@qq.com", 0, new Department(105, "教研部")));
    }

    //自增id
    public static Integer initId = 1006;

    //增加员工
    public void save(Employee employee) {
        if (employee.getId() == null) {
            employee.setId(initId++);
        }
        System.out.println("---------------------进行前");
        employee.setDepartment(departmentDao.getDepartmentById(employee.getDepartment().getId()));
        System.out.println("---------------------进行后");
        employees.put(employee.getId(),employee);
    }

    //查询全部员工信息
    public Collection<Employee> getAll() {
        return employees.values();
    }

    //通过id查询员工
    public Employee getEmployeeById(Integer id) {
        return employees.get(id);
    }

    public void delete(Integer id){
        employees.remove(id);
    }
}

1.实体类字段需要与数据库对应

2.实体类的数据类型需要与数据库对应

3.莫名其妙的thymeleaf语法居然可以使用:
th:if=”${dept.getDid()} eq ${emp.getDepartment()}” th:text=”${dept.getDepartmentName()}
这行代码的逻辑为if (a == b) { text = c; }

th:if可能在前端上可以用作if的逻辑判断，没有试过使用其他

    <tr th:each="emp:${emps}">
    <td th:text="${emp.getId()}"></td>
    <td th:text="${emp.getLastName()}"></td>
    <td th:text="${emp.getEmail()}"></td>
    <td th:text="${emp.getGender()==1?'男':'女'}"></td>
    <td th:each="dept:${departments}" th:if="${dept.getDid()} eq ${emp.getDepartment()}" th:text="${dept.getDepartmentName()}"></td>
    <td th:text="${#dates.format(emp.getBirth(),'yyyy-MM-dd HH:mm:ss')}"></td>
    <td>
        <a class="btn btn-sm btn-primary" th:href="@{/emp/}+${emp.getId()}">编辑</a>
        <a class="btn btn-sm btn-danger" th:href="@{/deleteEmp/}+${emp.getId()}">删除</a>
    </td>
</tr>