Spring Data JPA动态查询 maven项目简单例子

项目结构如下：

pom.xml

<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/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><groupId>cn.db</groupId><artifactId>psql</artifactId><packaging>war</packaging><version>0.0.1-SNAPSHOT</version><name>psql Maven Webapp</name><url>http://maven.apache.org</url><dependencies><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.10</version><scope>test</scope></dependency><dependency><groupId>commons-dbcp</groupId><artifactId>commons-dbcp</artifactId><version>1.4</version></dependency><dependency><groupId>javax.servlet</groupId><artifactId>jsp-api</artifactId><version>2.0</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.5</version></dependency><dependency><groupId>org.springframework.data</groupId><artifactId>spring-data-jpa</artifactId><version>1.6.1.RELEASE</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId><version>1.1.4.RELEASE</version></dependency><dependency><groupId>org.apache.maven.plugins</groupId><artifactId>maven-resources-plugin</artifactId><version>2.6</version></dependency></dependencies><repositories><repository><id>spring-milestones</id><url>http://repo.spring.io/libs-milestone</url></repository></repositories><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><configuration><source>1.8</source><target>1.8</target></configuration></plugin></plugins></build></project>

persistence.xml

<?xml version="1.0" encoding="UTF-8"?><persistence xmlns="http://java.sun.com/xml/ns/persistence"version="2.0"><persistence-unit name="SimplePU" transaction-type="RESOURCE_LOCAL"><provider>org.hibernate.ejb.HibernatePersistence</provider><properties><property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" /><property name="hibernate.connection.url" value="jdbc:mysql://127.0.0.1:3306/db_cloud" /><property name="hibernate.connection.username" value="root" /><property name="hibernate.connection.password" value="root" /><property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect" /><property name="hibernate.show_sql" value="true" /><property name="hibernate.format_sql" value="true" /><property name="hibernate.use_sql_comments" value="false" /><property name="hibernate.hbm2ddl.auto" value="update" /></properties></persistence-unit></persistence> 

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"xmlns:jpa="http://www.springframework.org/schema/data/jpa"xsi:schemaLocation="          http://www.springframework.org/schema/beans          http://www.springframework.org/schema/beans/spring-beans.xsd          http://www.springframework.org/schema/tx          http://www.springframework.org/schema/tx/spring-tx.xsd          http://www.springframework.org/schema/data/jpa    http://www.springframework.org/schema/data/jpa/spring-jpa.xsd        http://www.springframework.org/schema/context          http://www.springframework.org/schema/context/spring-context.xsd"><bean name="dataSource" class="org.apache.commons.dbcp.BasicDataSource"><property name="driverClassName"><value>com.mysql.jdbc.Driver</value></property><property name="url"><value>jdbc:mysql://127.0.0.1:3306/db_cloud</value></property><property name="username" value="root" /><property name="password" value="root" /></bean><bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"><property name="entityManagerFactory" ref="entityManagerFactory" /></bean><tx:annotation-driven transaction-manager="transactionManager" proxy-target-class="true"/><bean id="entityManagerFactory"class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"></bean><jpa:repositories base-package="cn.db.psql"entity-manager-factory-ref="entityManagerFactory"transaction-manager-ref="transactionManager" /></beans>  

Person.java

package cn.db.psql;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.Table;@Entity@Table(name = "ts_person") public class Person {@Column@Id@GeneratedValue(strategy=GenerationType.IDENTITY)private Integer userid;@Columnprivate String username;@Columnprivate String stype;@Columnprivate Integer city_id;public Integer getUserid() {return userid;}public void setUserid(Integer userid) {this.userid = userid;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getStype() {return stype;}public void setStype(String stype) {this.stype = stype;}public Integer getCity_id() {return city_id;}public void setCity_id(Integer city_id) {this.city_id = city_id;}public String toString(){return "[userid="+userid+",username="+username+",stype="+stype+",city_id="+city_id+"]";}}

PersonJpaSpecificationExecutor.java

package cn.db.psql;import java.util.List;import org.springframework.data.domain.Page;import org.springframework.data.domain.Pageable;import org.springframework.data.jpa.domain.Specification;import org.springframework.data.jpa.repository.JpaRepository;import org.springframework.data.jpa.repository.JpaSpecificationExecutor;import org.springframework.stereotype.Repository;/** * 复杂条件的查询 */@Repository("personJpaSpecificationExecutor")public interface PersonJpaSpecificationExecutor extends JpaRepository<Person, Long>, JpaSpecificationExecutor<Person> {Page<Person> findAll(Specification<Person> spec, Pageable pageable);  //分页按条件查询  List<Person> findAll(Specification<Person> spec);}

PersonRepository.java

package cn.db.psql;import org.springframework.data.jpa.repository.JpaRepository;import org.springframework.data.jpa.repository.Query;import org.springframework.data.repository.query.Param;import org.springframework.stereotype.Repository;/** * 简单的查询 */@Repository("personRepository")public interface PersonRepository extends JpaRepository<Person, Long> {@Query("select a from Person a where a.userid = :userid")public Person findByUserid(@Param("userid")Integer userid);}

PersonSpecification.java

package cn.db.psql;import java.util.ArrayList;import java.util.List;import javax.persistence.criteria.CriteriaBuilder;import javax.persistence.criteria.CriteriaQuery;import javax.persistence.criteria.Path;import javax.persistence.criteria.Predicate;import javax.persistence.criteria.Root;import org.springframework.data.jpa.domain.Specification;public class PersonSpecification implements Specification<Person>{private String _username;private String _stype;private Integer _cityId;public PersonSpecification(String username, String stype, Integer cityId){this._username = username;this._stype = stype;this._cityId = cityId;}public Predicate toPredicate(Root<Person> root, CriteriaQuery<?> query,CriteriaBuilder cb) {Path<String> username = root.get("username");Path<String> stype = root.get("stype");Path<Integer> city_id = root.get("city_id");List<Predicate> list = new ArrayList<Predicate>(); Predicate pa = cb.equal(username, _username);Predicate pb = cb.equal(stype, _stype);Predicate pc = cb.equal(city_id, _cityId);if(_username != null){list.add(pa);}if(_stype != null){list.add(pb);}if(_cityId != null){list.add(pc);}Predicate[] parray = new Predicate[list.size()];return cb.and(list.toArray(parray));}public String get_username() {return _username;}public void set_username(String _username) {this._username = _username;}public String get_stype() {return _stype;}public void set_stype(String _stype) {this._stype = _stype;}public Integer get_cityId() {return _cityId;}public void set_cityId(Integer _cityId) {this._cityId = _cityId;}}

Client.java

package cn.db.psql;import java.util.List;import org.springframework.context.support.ClassPathXmlApplicationContext;public class Client {public static void find() throws Exception{ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml"); try{PersonJpaSpecificationExecutor ur = (PersonJpaSpecificationExecutor)ctx.getBean("personJpaSpecificationExecutor");PersonSpecification us = new PersonSpecification(null,"1",1);List<Person> plist = ur.findAll(us);System.out.println("==============================================");for(Person p : plist){System.out.println(p);}System.out.println("==============================================");}catch(Exception e){e.printStackTrace();}ctx.close();}public static void main(String[] args) throws Exception{find();}}