初识SpringDataJpa

SpringDataJpa入门指南

最新推荐文章于 2022-05-20 10:09:04 发布

原创最新推荐文章于 2022-05-20 10:09:04 发布 · 189 阅读

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本文详细介绍如何在IDEA中创建使用SpringDataJpa的maven web项目，包括配置pom.xml引入依赖、设置applicationContext.xml，以及SpringDataJpa的重要接口和基本功能。涵盖自定义高级查询、JpaSpecificationExecutor使用和jpa-spec插件介绍。

SpringDataJpa初识

1.使用IDEA创建一个maven的web项目

1.1 在pom.xml中引入项目中需要使用的包

 <properties><!-- 统一jar包的版本 -->
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <org.springframework.version>4.2.5.RELEASE</org.springframework.version>
    <org.hibernate.version>4.3.8.Final</org.hibernate.version>
    <spring-data-jpa.version>1.9.0.RELEASE</spring-data-jpa.version>
    <com.fasterxml.jackson.version>2.5.0</com.fasterxml.jackson.version>
    <org.slf4j.version>1.6.1</org.slf4j.version>
  </properties>
  <dependencies>
    <!-- Spring的支持包 -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
      <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context-support</artifactId>
      <version>${org.springframework.version}</version>
    </dependency>

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-orm</artifactId>
      <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-aop</artifactId>
      <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>${org.springframework.version}</version>
      <scope>test</scope>
    </dependency>
    <!-- 引入web前端的支持 -->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-web</artifactId>
      <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>${org.springframework.version}</version>
    </dependency>
    <!-- SpringMCV上传需要用到io包-->
    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-io</artifactId>
      <version>1.3.2</version>
    </dependency>
    <!-- 文件上传用到的包 -->
    <dependency>
      <groupId>commons-fileupload</groupId>
      <artifactId>commons-fileupload</artifactId>
      <version>1.2.2</version>
    </dependency>
    <!-- SpringMVC的json支持包 -->
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>${com.fasterxml.jackson.version}</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-annotations</artifactId>
      <version>${com.fasterxml.jackson.version}</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>${com.fasterxml.jackson.version}</version>
    </dependency>
    <!-- hibernate的支持包 -->
    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-core</artifactId>
      <version>${org.hibernate.version}</version>
    </dependency>
    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-entitymanager</artifactId>
      <version>${org.hibernate.version}</version>
    </dependency>
    <!-- SpringData的支持包 -->
    <dependency>
      <groupId>org.springframework.data</groupId>
      <artifactId>spring-data-jpa</artifactId>
      <version>${spring-data-jpa.version}</version>
    </dependency>
    <!-- SpringData的擴展包 -->
    <dependency>
      <groupId>com.github.wenhao</groupId>
      <artifactId>jpa-spec</artifactId>
      <version>3.1.1</version>
      <!-- 把所有的依賴都去掉 -->
      <exclusions>
        <exclusion>
          <groupId>*</groupId>
          <artifactId>*</artifactId>
        </exclusion>
      </exclusions>
    </dependency>

    <dependency>
      <groupId>commons-dbcp</groupId>
      <artifactId>commons-dbcp</artifactId>
      <version>1.2.2</version>
    </dependency>

    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.6</version>
    </dependency>

    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-lang3</artifactId>
      <version>3.5</version>
    </dependency>
    <!-- 測試包 -->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.1.0</version>
      <!-- 这个scope 只能作用在编译和测试时，同时没有传递性。表示在运行的时候不添加此jar文件 -->
      <scope>provided</scope>
    </dependency>
    <!-- 日志文件 -->
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
      <version>${org.slf4j.version}</version>
    </dependency>
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-log4j12</artifactId>
      <version>${org.slf4j.version}</version>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>log4j</groupId>
      <artifactId>log4j</artifactId>
      <version>1.2.14</version>
    </dependency>
    <!-- 代码生成器模版技术 -->
    <dependency>
      <groupId>org.apache.velocity</groupId>
      <artifactId>velocity</artifactId>
      <version>1.6</version>
    </dependency>
  <!-- shiro的支持包 -->
   <dependency>
      <groupId>org.apache.shiro</groupId>
      <artifactId>shiro-all</artifactId>
      <version>1.4.0</version>
      <type>pom</type>
  </dependency>
    <!-- shiro与Spring的集成包 -->
    <dependency>
      <groupId>org.apache.shiro</groupId>
      <artifactId>shiro-spring</artifactId>
      <version>1.4.0</version>
    </dependency>
    <!-- poi支持的jar包 -->
    <dependency>
      <groupId>org.apache.poi</groupId>
      <artifactId>poi</artifactId>
      <version>3.11</version>
    </dependency>
    <dependency>
      <groupId>org.apache.poi</groupId>
      <artifactId>poi-ooxml</artifactId>
      <version>3.11</version>
    </dependency>
    <!-- 图片压缩功能 -->
    <!-- 缩略图 -->
    <dependency>
      <groupId>net.coobird</groupId>
      <artifactId>thumbnailator</artifactId>
      <version>0.4.6</version>
    </dependency>
    <!-- 定时调度 -->
    <dependency>
      <groupId>quartz</groupId>
      <artifactId>quartz</artifactId>
      <version>1.5.2</version>
    </dependency>
    <!-- 邮件支持 -->
    <dependency>
      <groupId>javax.mail</groupId>
      <artifactId>mail</artifactId>
      <version>1.4.1</version>
    </dependency>
  </dependencies>

  <build>
    <finalName>mdt</finalName>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.mortbay.jetty</groupId>
        <artifactId>jetty-maven-plugin</artifactId>
        <version>8.1.15.v20140411</version>
        <configuration>
          <stopPort>9966</stopPort>
          <stopKey>foo</stopKey>
          <webAppConfig>
            <contextPath>/</contextPath>
          </webAppConfig>
        </configuration>
      </plugin>
    </plugins>
  </build>

1.2配置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: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/context
         http://www.springframework.org/schema/context/spring-context.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">

    <!-- 扫描service部分的包 -->
    <context:component-scan base-package="com.wzy.service" />
    <context:property-placeholder location="classpath:jdbc.properties" />

    <!-- 配置连接池 -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <!--连接数据4个属性 -->
        <property name="driverClassName" value="${jdbc.driverClassName}" />
        <property name="url" value="${jdbc.url}" />
        <property name="username" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
        
    </bean>

    <!-- 集成hibernate的jpa功能 -->
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <!--待扫描的实体类包，不再需要persistence.xml了 -->
        <property name="packagesToScan" value="cn.itsource.aisell.domain" />
        <!-- 3.配置JPA的实现 -->
        <!-- private JpaVendorAdapter jpaVendorAdapter; -->
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <!-- org.springframework.orm.jpa.vendor.AbstractJpaVendorAdapter -->
                <!-- private boolean showSql = false;是否显示sql语句 -->
                <property name="showSql" value="true" />
                <!-- private boolean generateDdl = false;是否建表 -->
                <property name="generateDdl" value="false" />
                <!-- private String databasePlatform;原来方言 -->
                <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
            </bean>
        </property>
    </bean>

    <!-- Jpa 事务配置 -->
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory" />
    </bean>
    <!-- 注解声明式事务管理 -->
    <tx:annotation-driven />

    <!-- Spring Data Jpa配置 ********************************************-->
    <!-- base-package:扫描的包 -->
    <jpa:repositories base-package="com.wzy.domain" transaction-manager-ref="transactionManager"
                      entity-manager-factory-ref="entityManagerFactory" />
</beans>

1.3 SpringDataJpa中重要的接口和实现类
接口：
Repository（org.springframework.data.repository.Repository
JpaRepository (org.springframework.data.jpa.repository.JpaRepository)
JpaSpecificationExecutor (org.springframework.data.jpa.repository.JpaSpecificationExecutor)
实现类：
SimpleJpaRepository(org.springframework.data.jpa.repository.support.SimpleJpaRepository)

2.SpringDataJpa的基本功能

建立好项目的结构

在Repository写接口继承接口JpaRepository再注入自定义接口的实现类，SpringDataJpa会自动写好实现完成注入，并且有增删改查，分页，排序以及高级查询的功能

3.自定义高级查询
由于高级查询的条件不是固定的很多时候需要自定义高级查询，那么只需要在自己写的接口中声明方法，加上@Query()
在括号中写jpql语句就可以自定义高级查询

4.JpaSpecificationExecutor的使用
自定义接口继承paSpecificationExecutor

//通过在findAll中传入Specification对象来完成高级查询，写匿名内部类实现Specification接口
List<Employee> emps = employeeRepository.findAll(
            new Specification<Employee>() {
                @Override
                public Predicate toPredicate(Root<Employee> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
                    Path path = root.get("username");//拿到要做查询的字段
                    Predicate p = cb.like(path, "%1%");//like代表做模糊查询，后面就是它的条件值
                    return p;
                }
            }
    );

Root<T> root:代表了可以查询和操作的实体对象的根，
                 可以通过它的 Path<Y> get(String attributeName); 这个方法拿到我们要操作的字段
                 注意:只可以拿到对应的T的字段(Employee)
CriteriaQuery<?> query:代表一个specific的顶层查询对象
                包含查询的各个部分,比如select,from,where,group by ,order by 等
                简单理解 就是它提供 了查询ROOT的方法(where,select,having)
CriteriaBuilder cb:用来构建CriteriaQuery的构建器对象(相当于条件或者说条件组合)
                构造好后以Predicate的形式返回

5.jpa-spec插件
这是一个对于咱们刚才的动态生成Query功能的一个封装版，如果我们使用这个插件，在完成查询与分页的时候功能会简单不少。

基于Spring Data Jpa的动态查询库 https://github.com/wenhao/jpa-spec

Specification<Employee> spec = Specifications.<Employee>and().like("username", "%1%").build();

List<Employee> emps = employeeRepository.findAll(spec);