Specifications动态查询

目录

1 Specifications单条件查询

 2 Specifications多条件查询

 3 Specifications模糊查询

4  Specifications的分页查询

 5 Specifications的排序分页查询

root：Root接口，代表查询的根对象，可以通过root获取实体中的属性

query：代表一个顶层查询对象，用来自定义查询

cb：用来构建查询，此对象里有很多条件方法

相关依赖：

    4.0.0
    
        org.springframework.boot
        spring-boot-starter-parent
        2.6.0
         
    
    com.liubujun
    springboot-jpa
    0.0.1-SNAPSHOT
    springboot-jpa
    Demo project for Spring Boot
    
        1.8
    
    
        
            org.springframework.boot
            spring-boot-starter
        

        
            org.projectlombok
            lombok
            true
        
        
            org.springframework.boot
            spring-boot-starter-test
            test
        
        
            org.springframework.boot
            spring-boot-starter-web
            2.4.0-SNAPSHOT
        
        
            org.springframework.boot
            spring-boot-starter-data-jpa
            2.4.0-SNAPSHOT
        
        
            mysql
            mysql-connector-java
            8.0.22
        
    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
                
                    
                        
                            org.projectlombok
                            lombok
                        
                    
                
            
        
    

相关配置文件：

server:
  port: 8099

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/skywalking?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=GMT%2B8
    username: root
    password: lj123456
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
    properties:
      hibernate:
        format_sql: true

dao层配置：

public interface UserRepository extends JpaRepository, JpaSpecificationExecutor {
}

实体类：

@Entity
@Table(name = "t_user")
@Data
public class User implements Serializable {
    @Id
    private Integer id;
    private String name;
    private String address;
    private Integer age;
    private Date createTime;
    
}

1 Specifications单条件查询

测试类：

    @Test
    public void testSpeci(){
        Optional one = userRepository.findOne(new Specification() {
            
            @Override
            public Predicate toPredicate(Root root, CriteriaQuery query, CriteriaBuilder cb) {
                Path