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概述

　　ORM映射为我们带来便利的同时，也失去了较大灵活性，如果SQL较复杂，要进行动态查询，那必定是一件头疼的事情（也可能是lz还没发现好的方法），记录下自己用的三种复杂查询方式。

环境

springBoot

IDEA2017.3.4

JDK8

pom.xml

<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.6.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.xmlxy</groupId> <artifactId>seasgame</artifactId> <version>0.0.1-SNAPSHOT</version> <name>seasgame</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <!--数据库连接--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> </dependency> <!-- 热启动等 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <scope>runtime</scope> <optional>true</optional> </dependency> <!--Java bean 实体--> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <!--swagger2 API 测试工具 --> <dependency> <groupId>io.springfox</groupId> <artifactId>springfox-swagger2</artifactId> <version>2.8.0</version> </dependency> <dependency> <groupId>io.springfox</groupId> <artifactId>springfox-swagger-ui</artifactId> <version>2.8.0</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-configuration-processor</artifactId> <optional>true</optional> </dependency> <!--安全框架认证--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> <dependency> <groupId>net.sf.json-lib</groupId> <artifactId>json-lib</artifactId> <version>2.2.2</version> <classifier>jdk15</classifier> </dependency> <!--汉字转拼音--> <dependency> <groupId>com.belerweb</groupId> <artifactId>pinyin4j</artifactId> <version>2.5.1</version> </dependency> <!-- thymeleaf模板 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId> </dependency> <!-- <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> 移除嵌入式tomcat插件 <exclusions> <exclusion> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-tomcat</artifactId> </exclusion> </exclusions> </dependency> --> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>3.1.0</version> <scope>provided</scope> </dependency> </dependencies> <packaging>war</packaging> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.8</source> <target>1.8</target> </configuration> </plugin> </plugins> <finalName>seasgame</finalName> <pluginManagement> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>2.3.2</version> <configuration> <encoding>${project.build.sourceEncoding}</encoding> <source>1.7</source> <target>1.7</target> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <configuration> <testFailureIgnore>true</testFailureIgnore> </configuration> </plugin> </plugins> </pluginManagement> </build></project>

@Query

当一个SQL较为复杂时，第一个想到的就是原生的SQL语句。如果只是简单的查询，那情况还没这么糟糕

@Query(value = " SELECT IFNULL(sum(right_num),0) sumRight FROM t_record WHERE record_owner_id = ?1 AND responder_no = ?2 ",nativeQuery = true) Map<String,Object> sumRightNum(int studentId,int responderNo);

但如果需要进行动态查询，或更改，那这个value就变得复杂了。

package com.xmlxy.seasgame.dao;import com.xmlxy.seasgame.entity.ScoreEntity;import org.springframework.data.jpa.repository.Modifying;import org.springframework.data.jpa.repository.Query;import org.springframework.data.repository.CrudRepository;import org.springframework.data.repository.query.Param;import org.springframework.transaction.annotation.Transactional;import java.util.List;/** * * Description: * @author hwc * @date 2019/9/5 * @return*/ public interface ScoreDao extends CrudRepository<ScoreEntity,Integer>{ /** * * Description: *@param scoreEntity * @author hwc * @date 2019/9/6 */ @Transactional(rollbackFor = Exception.class) @Modifying @Query(value = "UPDATE t_score t SET " + "t.responder_no = CASE WHEN :#{#scoreEntity.responderNo} IS NULL THEN t.responder_no ELSE :#{#scoreEntity.responderNo} END," + "t.max_level = CASE WHEN :#{#scoreEntity.maxLevel} IS NULL THEN t.max_level ELSE :#{#scoreEntity.maxLevel} END," + "t.right_num = CASE WHEN :#{#scoreEntity.rightNum} IS NULL THEN t.right_num ELSE :#{#scoreEntity.rightNum} END," + "t.use_time = CASE WHEN :#{#scoreEntity.userTime} IS NULL THEN t.use_time ELSE :#{#scoreEntity.userTime} END WHERE student_id = :#{#scoreEntity.getStudentId()}",nativeQuery = true) void updateScore(@Param("scoreEntity") ScoreEntity scoreEntity);}

JPQL

如果Java代码内发出JPQL查询，就需要利用到EntityManager的响应方法了。一般执行以下流程

获取一个EntityManager实例

调用实例的方法createQuery，创建一个Query实例，如果有需要可以指定检索的最大数量和起始位置

使用Query方法getResultList执行查询，当然更新和删除操作得使用executeUpdate执行

进行一个复杂的动态SQL查询

public Page<RankEntity> getScoreByRank(int gradeId,int classId,Pageable pageable) { StringBuilder countSelectSql = new StringBuilder(""); countSelectSql.append(" SELECT COUNT(*) "); countSelectSql.append(" FROM "); countSelectSql.append(" t_score s, "); countSelectSql.append(" t_student st "); countSelectSql.append(" WHERE "); countSelectSql.append(" s.student_id = st.student_id "); StringBuilder selectSql = new StringBuilder(); selectSql.append(" SELECT s.student_id,st.real_name,st.student_class,s.max_level,s.use_time,s.right_num "); selectSql.append(" FROM t_score s "); selectSql.append(" JOIN t_student st ON s.student_id = st.student_id "); selectSql.append(" WHERE 1 = 1 "); Map<String,Object> params = new HashMap<>(); StringBuilder whereSql = new StringBuilder(); if (gradeId != -1) { whereSql.append(" AND st.student_grade = :student_grade "); params.put("student_grade",gradeId); } /**班级ID*/ if (classId != -1) { whereSql.append(" AND st.student_class = :classId "); params.put("classId",classId); } String orderSql = " ORDER BY s.max_level DESC,s.use_time,s.right_num ASC "; String countSql = new StringBuilder().append(countSelectSql).append(whereSql).toString(); Query countQuery = entityManager.createNativeQuery(countSql); for (Map.Entry<String,Object> entry : params.entrySet()) { countQuery.setParameter(entry.getKey(),entry.getValue()); } BigInteger totalCount = (BigInteger)countQuery.getSingleResult(); String querySql = new StringBuilder().append(selectSql).append(whereSql).append(orderSql).toString(); Query query = entityManager.createNativeQuery(querySql,RankEntity.class); for (Map.Entry<String,Object> entry:params.entrySet()) { query.setParameter(entry.getKey(),entry.getValue()); } query.setFirstResult((int) pageable.getOffset()); query.setMaxResults(pageable.getPageSize()); List<RankEntity> rankEntities = query.getResultList(); Page<RankEntity> page = new PageImpl<>(rankEntities,pageable,totalCount.longValue()); return page; }

注意：如果没有重新定义Pageable那么pageNumber必须减1，因为是从0开始的。

Criteria

这是一种规范查询是以元模型的概念为基础的，这个元模型可以是实体累，嵌入类，或者映射的父类，简单介绍几个里面用到接口。

CriteraQuery是一个特定的顶层查询对象，里面包含select，from，where，order by等各个部分，然而他只对实体类或嵌入类的标准查询起作用。

Root标准查询的根对象，根定义了实体类型，是你想要查询要获得的结果，也可以添加查询条件，结合实体管理对象得到查询的对象。

CriteriaBuilder接口用来构建CritiaQuery的构建器

StudentEntity类

package com.xmlxy.seasgame.entity;import io.swagger.annotations.ApiModel;import lombok.Data;import javax.persistence.*;import javax.print.attribute.standard.MediaSize;import java.io.Serializable;/** * * Description:学生对象 * @param * @author hwc * @date 2019/8/8 */@Entity@Table(name = "t_base_student")@ApiModel@Datapublic class StudentEntity implements Serializable{ private static final long serialVersionUID = 546L; @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "student_id") private Integer studentId; @Column(name = "student_grade") private Integer studentGrade; @Column(name = "student_class") private Integer studentClass; @Column(name = "address") private String address; @Column(name = "telephone") private Integer telephone; @Column(name = "real_name") private String realName; @Column(name = "id_number") private String idNumber; @Column(name = "study_id") private String studyId; @Column(name = "is_delete") private int isDelete; @Column(name = "uuid") private String uuid;}

dao层

public interface StudentDao extends JpaRepository<StudentEntity,Integer>,JpaSpecificationExecutor{}

动态查询

public Page<StudentEntity> getTeacherClassStudent(int pageNumber,int pageSize,int gradeId, int classId,String keyword) { pageNumber = pageNumber < 0 ? 0 : pageNumber; pageSize = pageSize < 0 ? 10 : pageSize; Specification<StudentEntity> specification = new Specification<StudentEntity>() { @Override public Predicate toPredicate(Root<StudentEntity> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) { //page : 0 开始, limit : 默认为 10 List<Predicate> predicates = new ArrayList<>(); predicates.add(criteriaBuilder.equal(root.get("studentGrade"),gradeId)); predicates.add(criteriaBuilder.equal(root.get("studentClass"),classId)); if (!Constant.isEmptyString(keyword)) { predicates.add(criteriaBuilder.like(root.get("realName").as(String.class),"%" + keyword + "%")); } return criteriaBuilder.and(predicates.toArray(new Predicate[predicates.size()])); } }; /*studentId必须是实体类属性与数据库对应，否则报ropertyReferenceException异常*/ PageRequest page = new PageRequest(pageNumber,pageSize,Sort.Direction.ASC,"studentId"); Page<StudentEntity> pages = studentDao.findAll(specification,page); return pages; }

因为这个项目应用比较简单，所以条件只有一个，如果条件较多，甚至可以定义一个专门的类去接收拼接参数，然后判

断，成立就add进去。

总结

以上所述是小编给大家介绍的JPA多条件复杂SQL动态分页查询功能，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对我们网站的支持！如果你觉得本文对你有帮助，欢迎转载，烦请注明出处，谢谢！

本文标题: JPA多条件复杂SQL动态分页查询功能

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