[Spring]常用注解和技术汇总

- 日理万妓 2021-09-18 10:00 344阅读 0赞

# 注解 #

## 常用注解 ##

@Valid    //使用hibernate validation的时候使用
    
    @Validated //用spring Validator 校验机制使用
    
    @Entity     //实体类
    
    @Table(name=" 表名")  
    
    @Id  // 主键
    
    @Pattern(regexp = "([a-z0-9A-Z]+[-|\\.]?)+[a-z0-9A-Z]@([a-z0-9A-Z]+(-[a-z0-9A-Z]+)?\\.)+[a-zA-Z]{2,}", message = "邮箱错误")
    
    @NotNull(message = "不能为空")
    
    @NotBlank   //检查约束字符串是不是Null，最少一个非空白字符.
    
    @Size(min=, max=) 验证对象（Array,Collection,Map,String）长度是否在给定的范围之内 
    
    @EnableTransactionManagement  // 启注解事务管理，等同于xml配置方式的 <tx:annotation-driven />
    
    @MapperScan(basePackages = "com.test.dao", markerInterface = MyMapper.class)
    
    
    // 加载properties中的配置
    @ConfigurationProperties("test")
    @Component
    @PropertySource("classpath:test.properties")

## 缓存注解 ##

@EnableCaching
    @ConditionalOnClass(RedisOperations.class)
    @EnableConfigurationProperties(RedisProperties.class)
    
    
        @ConditionalOnMissingBean(name = "redisTemplate")

> 缓存注解的文章 [https://blog.csdn.net/dreamhai/article/details/80642010][https_blog.csdn.net_dreamhai_article_details_80642010]

## 主键注解生成策略 ##

[主键生成策略][Link 1]  
//生成32位UUID 不是标准的uuid而是去掉横杠的

@GenericGenerator(name = "idGenerator", strategy = "uuid") 
            @GeneratedValue(generator = "idGenerator")
    
    //完整写法
    	@GenericGenerator(name = "idGenerator", strategy = "org.hibernate.id.UUIDGenerator")
        @GeneratedValue(generator = "idGenerator")

## 常用的时间注解 ##

### 该注解被insert 时会被触发 ###

@CreatedDate   创建时间
    @CreatedBy   创建人
    @LastModifiedDate
    @LastModifiedBy

### 使用方法 ###

1.  在启动类上添加 @EnableJpaAuditing
2.  在entity类上添加 @EntityListeners(AuditingEntityListener.class)
3.  在字段上添加 @CreatedDate

# 查询 #

// 继承接口
    public interface **Repository extends JpaRepository<PjPrj, String>, JpaSpecificationExecutor { 
    }

## 关联关系 ##

### 一对一 ###

// 一个人只养一只狗
    
    // Person
     	@OneToOne(targetEntity = Dog.class, cascade = CascadeType.PERSIST)
     	
        @JoinColumn(name = "dogid", referencedColumnName = "id")
        private Dog dog;
    
    //Dog

![在这里插入图片描述][20190309104450189.png]  
person 表中就会将dog的id主键作为外键进行关联，完成一对一的关联关系

### 一对多 ###

### 多对多 ###

## 条件查询 ##

@Override
        public Page queryAll(PjPrj resources, Pageable pageable, String time) { 
    
            Page all = pjPrjRepository.findAll(new Specification() { 
    
                @Override
                public Predicate toPredicate(Root root, CriteriaQuery query, CriteriaBuilder criteriaBuilder) { 
                    List<Predicate> list = new ArrayList<Predicate>();
                    //todo 条件查询
    
                    if (!ObjectUtils.isEmpty(resources.getPjn())) { 
                        list.add(criteriaBuilder.equal(root.get("pjn"), resources.getPjn()));
                    }
    
                    if (!ObjectUtils.isEmpty(time)) { 
                        String[] split = time.split(",");
    
                        SimpleDateFormat sdfmat = new SimpleDateFormat("yyyy-MM-dd");
                        try { 
    
                            list.add(criteriaBuilder.between(root.get("createtime"),
                                    sdfmat.parse(split[0]),
                                    sdfmat.parse(split[1])));
                        } catch (ParseException e) { 
                            e.printStackTrace();
                        }
                    }
    
                    Predicate[] p = new Predicate[list.size()];
                    return criteriaBuilder.and(list.toArray(p));
                }
            }, pageable);
    
            return all;
        }

# 数据库配置 #

#配置 Jpa
     spring:
      datasource:
        type: com.alibaba.druid.pool.DruidDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        url: jdbc:mysql://localhost:3306/test
        username: root
        password: root
     
    
    
      #配置 Jpa
      jpa:
        properties:
          hibernate:
            dialect: org.hibernate.dialect.MySQL5InnoDBDialect
        # format_sql: true # 格式化 生成的sql
        open-in-view: true
      # show-sql: true # 显示sql语句

[https_blog.csdn.net_dreamhai_article_details_80642010]: https://blog.csdn.net/dreamhai/article/details/80642010
[Link 1]: https://www.cnblogs.com/hoobey/p/5508992.html
[20190309104450189.png]: /images/20210812/f939efbce97345b7be729ccf24560e2e.png