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Spring Data JPA 通过 Query DSL查询数据

昨天写 JPA的查询方式，里面关于QueryDSL的部分没有写，当时因为一直报错，现在错误解决了，补上 Spring Data JPA 通过 Query DSL 查询的实现。

另2篇地址：

Spring Data JPA 的查询方式

You need to run build with JDK or have tools.jar on the classpath

pom

<dependency>
    <groupId>com.querydsl</groupId>
    <artifactId>querydsl-apt</artifactId>
</dependency>
<dependency>
    <groupId>com.querydsl</groupId>
    <artifactId>querydsl-jpa</artifactId>
</dependency>
<dependency>
    <groupId>com.sun</groupId>
    <artifactId>tools</artifactId>
    <version>1.7</version>
    <scope>system</scope>
    <systemPath>${JAVA_HOME}/lib/tools.jar</systemPath>
</dependency>

官网和一些其他示例并没有提及tools，但没有这个会报错的，IDE里面就报了。

除了上面的配置还要添加构建插件

<build>
    <plugins>
        <plugin>
            <groupId>com.mysema.maven</groupId>
            <artifactId>apt-maven-plugin</artifactId>
            <version>1.1.3</version>
            <executions>
                <execution>
                    <goals>
                        <goal>process</goal>
                    </goals>
                    <configuration>
                        <outputDirectory>target/generated-sources/java</outputDirectory>
                        <processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

配置完这些之后 Dao需要多继承一个接口QueryDslPredicateExecutor

package com.school1024.spring.boot.data.jpa.dao;
 
import java.util.List;
import java.util.Map;
 
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.querydsl.QueryDslPredicateExecutor;
import org.springframework.data.repository.query.Param;
 
import com.school1024.spring.boot.data.jpa.model.BookModel;
import com.school1024.spring.boot.data.jpa.model.type.GenderType;
 
public interface BookDao extends JpaRepository<BookModel, Integer>, JpaSpecificationExecutor<BookModel>,
        QueryDslPredicateExecutor<BookModel> {
 
}

这个接口里的方法可以接收 com.querydsl.core.types.Predicate 类型的参数，注意这个类型是querydsl的，与 javax.persistence.criteria.Predicate 是有区别的。

测试用例

@Test
public void test9() {
    QBookModel qbook = QBookModel.bookModel;
 
    com.querydsl.core.types.Predicate predicate = qbook.gender.eq(GenderType.MALE).and(qbook.name.like("%张三%"));
 
    Iterable<BookModel> rs = dao.findAll(predicate);
 
    for (BookModel bookModel : rs) {
        System.out.println(bookModel);
    }
 
}

输出结果：BookModel [id=1, name=张三疯自传, author=张三, gender=MALE]

测试数据参考：http://www.school1024.com/spring/spring-data-jpa-query-example.html

更多Querydsl用法参考：http://www.querydsl.com/

原文 http://www.school1024.com/spring/spring-data-jpa-via-query-dsl-querydata.html

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