Spring Data JPA 整合 QueryDSL

Querydsl是一个框架，使得能够使用fluent API构造SQL类似的查询。

添加依赖和插件

        <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>

<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>src/generated-sources/java</outputDirectory>
                            <processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

生成@Entity注解类的查询类型

执行mvn 的compile,会在src/generated-sources/java下生成相应的查询类型，比如我有一个@Entity标注的Book类，将生成Qbook,生成的Qbook如下：

import static com.querydsl.core.types.PathMetadataFactory.*;

import com.querydsl.core.types.dsl.*;

import com.querydsl.core.types.PathMetadata;
import javax.annotation.Generated;
import com.querydsl.core.types.Path;

/**
 * QBook is a Querydsl query type for Book
 */
@Generated("com.querydsl.codegen.EntitySerializer")
public class QBook extends EntityPathBase<Book> {

    private static final long serialVersionUID = -1562182694L;

    public static final QBook book = new QBook("book");

    public final StringPath author = createString("author");

    public final StringPath description = createString("description");

    public final NumberPath<Long> id = createNumber("id", Long.class);

    public final StringPath isbn = createString("isbn");

    public final StringPath reader = createString("reader");

    public final StringPath title = createString("title");

    public QBook(String variable) {
        super(Book.class, forVariable(variable));
    }

    public QBook(Path<? extends Book> path) {
        super(path.getType(), path.getMetadata());
    }

    public QBook(PathMetadata metadata) {
        super(Book.class, metadata);
    }

}

修改Repository接口继承QueryDslPredicateExecutor

interface ReadingBookRepository extends JpaRepository<Book, Long>, QueryDslPredicateExecutor<Book> {
……
}

使用新的仓库接口

       QBook book = QBook.book;
        Predicate authorEqual = book.author.equalsIgnoreCase(author);
        Book one = readingBookRepository.findOne(authorEqual);

babyachievement / notes

Spring Data JPA 整合 QueryDSL #19