Spring Data JPA动态查询 maven项目简单例子

r囧r小猫 2022-09-21 01:03 259阅读 0赞

项目结构如下：

![SouthEast][]

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;
    	
    	@Column
    	private String username;
    	
    	@Column
    	private String stype;
    	
    	@Column
    	private 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();
    	}
    }

[SouthEast]: /images/20220823/17d908b023d44131a94e3b7a38050c23.png