springData使用QueryDsl的示例代码

经过多年,spring data jpa越来越完善,在版本迭代的过程中,会不断增加功能,今天看新的reference发现有Querydsl.然后搜索到上面的参考资料2

无论是JpaSpecificationExecutor,还是QueryDslPredicateExecutor,它俩都提供了使用Predicate(意义相同,都是构建where子句;类不同,javax.persistence.criteria.Predicate,com.querydsl.core.types.Predicate)去构建查询,使用比较方便.

关于两者的简单使用,上面的参考资料2有介绍.文末也有总结,从概括来看,我个人认为应倾向使用QueryDslPredicateExecutor,QueryDsl不仅适用于JPA repositories,还支持MongoDB.

下面是个例子

1.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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.exam</groupId>
  <artifactId>testjava</artifactId>
  <version>1.0.0</version>
  <name>${project.artifactId}</name>
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
    <spring.version>4.2.5.RELEASE</spring.version>
    <spring-data.version>Hopper-SR1</spring-data.version>
    <querydsl.version>4.1.1</querydsl.version>
    <hibernate.version>5.1.0.Final</hibernate.version>
    <tomcat.version>8.0.32</tomcat.version>
    <logback.version>1.1.7</logback.version>
    <mysql.version>5.1.33</mysql.version>
    <junit.version>4.12</junit.version>
  </properties>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-framework-bom</artifactId>
        <version>${spring.version}</version>
        <scope>import</scope>
        <type>pom</type>
      </dependency>
      <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-releasetrain</artifactId>
        <version>${spring-data.version}</version>
        <scope>import</scope>
        <type>pom</type>
      </dependency>
    </dependencies>
  </dependencyManagement>
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.1</version>
        <configuration>
          <source>${java.version}</source>
          <target>${java.version}</target>
        </configuration>
      </plugin>
      <plugin>
        <groupId>com.mysema.maven</groupId>
        <artifactId>maven-apt-plugin</artifactId>
        <version>1.0.4</version>
        <executions>
          <execution>
            <phase>generate-sources</phase>
            <goals>
              <goal>process</goal>
            </goals>
            <configuration>
              <outputDirectory>target/generated-sources</outputDirectory>
              <processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  <dependencies>
    <dependency>
      <groupId>org.springframework.data</groupId>
      <artifactId>spring-data-jpa</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.data</groupId>
      <artifactId>spring-data-mongodb</artifactId>
    </dependency>
    <dependency>
      <groupId>com.querydsl</groupId>
      <artifactId>querydsl-apt</artifactId>
      <version>${querydsl.version}</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>com.querydsl</groupId>
      <artifactId>querydsl-jpa</artifactId>
      <version>${querydsl.version}</version>
    </dependency>
    <dependency>
      <groupId>com.querydsl</groupId>
      <artifactId>querydsl-mongodb</artifactId>
      <version>${querydsl.version}</version>
    </dependency>
    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-entitymanager</artifactId>
      <version>${hibernate.version}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.tomcat</groupId>
      <artifactId>tomcat-jdbc</artifactId>
      <version>${tomcat.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
    </dependency>
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
      <version>${logback.version}</version>
    </dependency>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>${mysql.version}</version>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>${junit.version}</version>
    </dependency>
  </dependencies>

  <repositories>
    <repository>
      <id>central</id>
      <name>Central Repository</name>
      <url>http://repo1.maven.org/maven2</url>
      <layout>default</layout>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
    </repository>
  </repositories>
</project>

2.Domain类

package org.exam.domain;

import org.springframework.data.mongodb.core.mapping.Document;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import java.io.Serializable;

@Entity
@Document
public class Employee implements Serializable {
  @Id
  @Column(length = 38)
  private String id;
  @Column(length = 32)
  private String name;
  private long salary;
  private long departmentId;
  //setter和getter略
}

3.Repository类

package org.exam.repository.jpa;
import org.exam.domain.Employee;
import org.springframework.data.querydsl.QueryDslPredicateExecutor;
import org.springframework.data.repository.PagingAndSortingRepository;
import java.util.Collection;
public interface JpaEmployeeRepository extends PagingAndSortingRepository<Employee,String>,QueryDslPredicateExecutor<Employee>{
  Collection<Employee> findByIdIn(Collection<String> ids);
}

package org.exam.repository.mongo;

import org.exam.domain.Employee;
import org.springframework.data.querydsl.QueryDslPredicateExecutor;
import org.springframework.data.repository.PagingAndSortingRepository;
import java.util.Collection;
public interface MongoEmployeeRepository extends PagingAndSortingRepository<Employee, String>, QueryDslPredicateExecutor<Employee> {
  Collection<Employee> findByIdIn(Collection<String> ids);
}

JPA有JpaRepository,MongoDB有MongoRepository,它俩都继承PagingAndSortingRepository

3.配置类

package org.exam.config;

import com.mongodb.MongoClient;
import com.mongodb.WriteConcern;
import org.apache.tomcat.jdbc.pool.DataSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.data.mongodb.MongoDbFactory;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.SimpleMongoDbFactory;
import org.springframework.data.mongodb.core.WriteResultChecking;
import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.Database;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.annotation.Resource;
import java.net.UnknownHostException;
import java.util.Properties;

@Configuration
@PropertySource("classpath:config.properties")
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = "org.exam.repository.jpa")
@EnableMongoRepositories(basePackages = "org.exam.repository.mongo")
public class AppConfig {
  @Resource
  private Environment env;

  @Bean(destroyMethod = "close")
  public DataSource dataSource() {
    DataSource dataSource = new DataSource();
    dataSource.setDriverClassName(env.getProperty("ds.driverClassName"));
    dataSource.setUrl(env.getProperty("ds.url"));
    dataSource.setUsername(env.getProperty("ds.username"));
    dataSource.setPassword(env.getProperty("ds.password"));
    dataSource.setInitialSize(env.getProperty("ds.initialSize", Integer.class));
    dataSource.setMinIdle(env.getProperty("ds.minIdle", Integer.class));
    dataSource.setMaxIdle(env.getProperty("ds.maxIdle", Integer.class));
    dataSource.setMaxActive(env.getProperty("ds.maxActive", Integer.class));
    return dataSource;
  }

  @Bean
  public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
    HibernateJpaVendorAdapter jpaVendorAdapter = new HibernateJpaVendorAdapter();
    jpaVendorAdapter.setDatabase(Database.valueOf(env.getProperty("jpa.database")));
    jpaVendorAdapter.setGenerateDdl(env.getProperty("jpa.generateDdl",Boolean.class));
    jpaVendorAdapter.setShowSql(env.getProperty("jpa.showSql",Boolean.class));
    LocalContainerEntityManagerFactoryBean emf = new LocalContainerEntityManagerFactoryBean();
    emf.setDataSource(dataSource());
    emf.setPackagesToScan("org.exam.domain");
    emf.setJpaVendorAdapter(jpaVendorAdapter);
    Properties properties = new Properties();
    properties.setProperty("hibernate.default_schema", env.getProperty("jpa.defaultSchema"));
    emf.setJpaProperties(properties);
    return emf;
  }

  @Bean
  public PlatformTransactionManager transactionManager() {
    return new JpaTransactionManager(entityManagerFactory().getObject());
  }

  @Bean
  public MongoDbFactory mongoDbFactory() throws UnknownHostException {
    return new SimpleMongoDbFactory(new MongoClient(env.getProperty("mongo.host"), env.getProperty("mongo.port", Integer.class)), env.getProperty("mongo.db"));
  }

  @Bean
  public MongoTemplate mongoTemplate() throws UnknownHostException {
    MongoTemplate mongoTemplate = new MongoTemplate(mongoDbFactory());
    mongoTemplate.setWriteResultChecking(WriteResultChecking.EXCEPTION);
    mongoTemplate.setWriteConcern(WriteConcern.NORMAL);
    return mongoTemplate;
  }
}

4.测试类

package org.exam.repository.jpa;

import org.exam.config.AppConfig;
import org.exam.domain.Employee;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.test.annotation.Rollback;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.support.AnnotationConfigContextLoader;
import org.springframework.transaction.annotation.Transactional;

import java.util.UUID;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(loader = AnnotationConfigContextLoader.class, classes = {AppConfig.class})
@Transactional(transactionManager = "transactionManager")//Rollback默认为true
public class JpaEmployeeRepositoryTest {
  @Autowired
  private JpaEmployeeRepository jpaEmployeeRepository;

  @Test
  @Rollback(false)
  public void testSave() {
    for (int i = 0; i < 5; i++) {
      Employee employee = new Employee();
      employee.setId(UUID.randomUUID().toString());
      employee.setName("name");
      employee.setDepartmentId(1 + i);
      employee.setSalary(6800 + i);
      jpaEmployeeRepository.save(employee);
    }
  }

  @Test
  public void testFindAll() {
    Page<Employee> all = jpaEmployeeRepository.findAll(null, new PageRequest(0, 8));
    for (Employee employee : all) {
      System.out.println("employee = " + employee);
    }
  }
}

package org.exam.repository.mongo;
import com.mongodb.MongoClient;
import org.exam.config.AppConfig;
import org.exam.domain.Employee;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.geo.Circle;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.support.AnnotationConfigContextLoader;
import java.net.UnknownHostException;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(loader = AnnotationConfigContextLoader.class, classes = {AppConfig.class})
public class MongoEmployeeRepositoryTest {
  @Autowired
  private MongoEmployeeRepository mongoEmployeeRepository;

  public static void main(String[] args) throws UnknownHostException {
    MongoTemplate template = new MongoTemplate(new MongoClient("127.0.0.1", 27017), "test");
    Circle circle = new Circle(-73.99171, 40.738868, 0.01);

    System.out.println();
  }

  @Test
  public void testFindAll() {
    Page<Employee> all = mongoEmployeeRepository.findAll(null, new PageRequest(0, 8));
    for (Employee employee : all) {
      System.out.println("employee = " + employee);
    }
  }
}

5.其它config.properties,logback.xml文件不太重要,篇幅关系就省略.

源码下载

再了解一下比较大的需求,从几张表来取几个字段的数据,返回分页排序数据.

1.在AppConfig注册JPAQueryFactory Bean

@Bean
public JPAQueryFactory jpaQueryFactory(EntityManager entityManager) {
  return new JPAQueryFactory(new HQLTemplates(), entityManager);
}

2.建一个DTO(数据传输对象)

public class UserDTO {
  private String empName;
  private String deptName;
  private long salary;
  //setter,getter略
}

3.查询例子测试

private Page<UserDTO> findAll(String empName,Pageable pageable) {
  QEmployee qEmp = QEmployee.employee;
  QDepartment qDep = QDepartment.department;
  List<Predicate> criteria = new ArrayList<>();
  if (StringUtils.hasText(empName)){
    criteria.add(qEmp.name.eq(empName.trim()));
  }

  JPAQuery<?> query = jpaQueryFactory.from(qEmp).innerJoin(qDep).on(qEmp.deptId.eq(qDep.id)).where(criteria.toArray(new Predicate[criteria.size()]));
  long total = query.fetchCount();
  List<UserDTO> content;
  if (pageable == null || total > pageable.getOffset()) {
    Map<String, SimpleExpression<?>> map = new HashMap<>();
    map.put("deptName", qDep.name);
    map.put("empName", qEmp.name);
    map.put("salary", qEmp.salary);
    content = QuerydslUtils.applyPagination(pageable, query).select(Projections.bean(UserDTO.class, map)).fetch();
  } else {
    content = Collections.emptyList();
  }
  return new PageImpl<>(content, pageable, total);
}

@Test
public void test() {
  Pageable pageable = new PageRequest(0, 10, new QSort(new OrderSpecifier<>(Order.DESC, QEmployee.employee.salary), new OrderSpecifier<>(Order.ASC, QDepartment.department.name)));
  Page<UserDTO> page = findAll("name", pageable);
  for (UserDTO userDTO : page) {
    System.out.println("userDTO = " + userDTO);
  }
}

参考资料

1:http://docs.spring.io/spring-data/jpa/docs/1.10.x/reference/pdf/spring-data-jpa-reference.pdf

2:https://spring.io/blog/2011/04/26/advanced-spring-data-jpa-specifications-and-querydsl/

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持呐喊教程。

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