springData使用QueryDsl的示例代码

时间：2022-09-22 21:31:50

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

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<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

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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

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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);
}
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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

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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

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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);
    }
  }
}
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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.

 

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

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@bean
public jpaqueryfactory jpaqueryfactory(entitymanager entitymanager) {
  return new jpaqueryfactory(new hqltemplates(), entitymanager);
}

2.建一个dto(数据传输对象)

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public class userdto {
  private string empname;
  private string deptname;
  private long salary;
  //setter,getter略
}

3.查询例子测试

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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服务器之家。

原文链接：https://blog.csdn.net/xiejx618/article/details/51480265

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