SpringBoot Layui

基于SpringBoot2.x + layui2.5.x + Thymeleaf + Mysql5.7 版本开发的后台管理系统

问题记录

1. springDataJpa动态代理扩展
   给所有的DAO接口添加相同的默认方法： https://blog.csdn.net/weixin_45138931/article/details/102979230
   https://www.petrikainulainen.net/programming/spring-framework/spring-data-jpa-tutorial-adding-custom-methods-into-all-repositories/

2. JPA 通过@Query和JPQL分页查询

   //JPQL
   @Query(value = "SELECT u FROM User u ORDER BY id")
   Page<User> findAllUsersWithPagination(Pageable pageable);
   
   // Native
   @Query(
           value = "SELECT * FROM Users ORDER BY id",
           countQuery = "SELECT count(*) FROM Users",
           nativeQuery = true)
   Page<User> findAllUsersWithPagination(Pageable pageable);

3. Mysql 5.7 创建create_time和update_time字段自动更新

    `create_time` datetime(0) NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
    `update_time` datetime(0) NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP(0) COMMENT '更新时间',

4. JPA 存在updateTime字段时，更新Entity对象，如果updateTime为Null，会导致数据库不自动更新update_time字段,并设置成NULL

    @EnableJpaAuditing
    @SpringBootApplication
    public class Springboot2DemoApplication {}
   
    // @LastModifiedDate 自动设置updateTime
    @Column(name = "update_time")
    @Temporal(TemporalType.TIMESTAMP)
    @JsonFormat
    @LastModifiedDate
    private Date updateTime;

5. Ignoring null Parameters Using the @Query Annotation

   @Query("SELECT c FROM Customer c WHERE (:name is null or c.name = :name) and (:email is null"
     + " or c.email = :email)")
   List<Customer> findCustomerByNameAndEmail(@Param("name") String name, @Param("email") String email);

6. HTML通过flex实现左右DIV布局

   <div style="display: flex;
             flex-flow: row nowrap;
             justify-content: space-between;">
       <div>left</div>
       <div>right</div>
   </div>

7. thymeleaf th:href添加URL参数

   <a th:href="@{/index(param1='value1',param2='value2')}">

8. thymeleaf 获取当前Request中的参数、Session参数 somesite.com/login?error=true

     <div id="errors" th:if="${(param.error != null) and (param.error[0] == 'true')}">
       Input is incorrect
       </div>

   session params

    ${session.foo} // Retrieves the session atttribute 'foo'
    ${session.size()}
    ${session.isEmpty()}
    ${session.containsKey('foo')}

9. thymeleaf Null 安全

   <td th:text="${user?.address?.city}"></td>
   <span th:text="${object.property} ? 'this is good' : 'default value'"></span>
   <span th:text="${object.property} ?: 'default value'"></span>

10. thymeleaf 字符串isEmpty判断

    ${#strings.isEmpty(name)}
    
    // is true if name is not empty
    ${!#strings.isEmpty(name)} or ${not #strings.isEmpty(name)}