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  • SpringDataJpa

    一.什么是SpringDataJpa

    一.什么是SpringDataJpa

    • 它是Spring的一个子框架
    • 集成Jpa,让咱们操作数据库变得更加的简单

    二.项目导包

    • 能够看懂这里导入了哪些包
    • 也可以理解这些包是做什么的
    <?xml version="1.0" encoding="UTF-8"?>
    
    <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>cn.itsource</groupId>
      <artifactId>aisell</artifactId>
      <version>1.0-SNAPSHOT</version>
      <packaging>war</packaging>
    
      <name>aisell Maven Webapp</name>
      <!-- FIXME change it to the project's website -->
      <url>http://www.example.com</url>
    
      <properties>
        <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>
        <!-- 上下文支持包(帮我们集成:模板,邮件,任务调度...) -->
        <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>
        <!-- SpringDataJpa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>
        <!--lang3:工具包 java.lang.-->
        <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(权限框架)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(操作办公软件)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>aisell</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>
    </project>
    

    三 集成SpringDataJpa

    3.1 完成Spring与Jpa的集成

    昨天已经详细讲解过(要求自己是可以把它写出来)

    3.1.1 准备db.propeties

    jdbc.driverClassName=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql:///aisell
    jdbc.username=root
    jdbc.password=123456
    

    3.2.2 准备applicationContext.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           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"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           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
    ">
        <!--扫描service层的类-->
        <context:component-scan base-package="cn.itsource.aisell.service" />
        <!--
            db.properties -> dataSource(配置数据源[连接池dbcp]) -> EntityManagerFactory -> dao -> service
                -> 事务 -> controller(集成SpringMVC) -> easyui
        -->
        <!--1.读取db.properties, 注意:不要忘了加classpath-->
        <context:property-placeholder location="classpath:db.properties" />
        <!--2.配置dbcp连接池-->
        <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
            <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>
        <!--
            JPA:ORM规范  -> 很多框架实现了这个规范(hibernate,openjpa,toplink,...)
            3.配置EntityManagerFactory对象
                3.1 基本配置都是写在Spring中(四大金刚,建表策略,方言,是否显示SQL)
                3.2 Spring来创建这个对象(准备一个domain,如果运行的时候创建了表,就代表这个对象是成功的)
                alt+insert -> JPA -> LocalContainerEntityManagerFactoryBean
                ctrl+t/f4 : 有办法看结构
        -->
        <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
            <property name="dataSource" ref="dataSource"/>
            <!--扫描JPA支持的注解-->
            <property name="packagesToScan" value="cn.itsource.aisell.domain" />
            <!--
                告诉Spring我们使用的是哪一个框架来完成JPA规范
                这里就需要我们配置一个适配器
                jpaVendorAdapter:JPA需要配置的适配器(我们会选择hibernate)
            -->
            <property name="jpaVendorAdapter">
                <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                    <!--方言-->
                    <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
                    <!--
                        建表策略
                    -->
                    <property name="generateDdl" value="false" />
                    <!--是否显示sql-->
                    <property name="showSql" value="true" />
                </bean>
            </property>
        </bean>
        <!--4.加上事务-->
        <!--4.1 准备事务管理器-->
        <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
            <property name="entityManagerFactory" ref="entityManagerFactory"/>
        </bean>
        <!--4.2 开启(注解)事务支持-->
        <tx:annotation-driven transaction-manager="transactionManager" />
    
    </beans>
    

    3.2 集成SpringDataJpa

    3.2.1 准备domain(父类)

    1. BaseDomain

    jpa中父类domain必需要加上:@MappedSuperclass

    /**
     * 泛化:继承关系
     * 在我们JPA,如果要抽取一个父类,就必需加上 @MappedSuperclass
     *  非常明确定的告诉JPA,这是一个用于映射的父类
     */
    @MappedSuperclass
    public class BaseDomain {
        @Id
        @GeneratedValue
        protected Long id;
    
       //getter,setter ...
    }
    
    1. Employeee
    
    @Entity
    @Table(name = "employee")
    public class Employee extends BaseDomain {
    
        private String username;
        private String password;
        private Integer age;
        private String email;
        //getter,setter ...
       
    }
    
    

    3.2.2 准备Repository接口

    /**
     * 关于Employee对象的CRUD(分页排序) 就写完了
     *  泛型一:对哪一个实体做CRUD
     *  泛型二:主键的类型
     */
    public interface EmployeeRepository extends JpaRepository<Employee,Long> {
        ...
    }
    

    3.2.3 扫描repository

    • repository 就是咱们过去的dao
    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
          ...
           xmlns:jpa="http://www.springframework.org/schema/data/jpa"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="
           http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
          ...
          http://www.springframework.org/schema/data/jpa
          http://www.springframework.org/schema/data/jpa/spring-jpa.xsd
    ">
       ...
    
        <!-- 让SpringDataJpa去扫描repository -->
        <jpa:repositories base-package="cn.itsource.aisell.repository"
                          entity-manager-factory-ref="entityManagerFactory"
                          transaction-manager-ref="transactionManager" />
    
    </beans>
    

    四.完成的CRUD功能

    4.1 基本的CRUD

    • 查询所有:employeeRepository.findAll()
    • 查询一条数据: employeeRepository.findOne(1L)
      • 思考题: findOne与getOne的区别?
    • 添加/修改: employeeRepository.save(employee)
      • 主要看数据库中是否有这个值
    • 删除 : employeeRepository.delete(274L)

    4.2 分页和排序

    4.2.1 排序

     /**
     * 排序对象
     *  第一个参数:排序的类型(升序还是降序)
     *  第二个参数:排序的属性
     */
    Sort sort = new Sort(Sort.Direction.DESC,"age");
    
    List<Employee> list = employeeRepository.findAll(sort);
    list.forEach(e-> System.out.println(e));
    

    4.2.2 分页

    注:这里的分页是从0开始的

    /**
     * page:第几页(0就是第1页)
     * size:每页条数
     */
    Pageable pageable = new PageRequest(0,10);
    //分页对象
    Page<Employee> list = employeeRepository.findAll(pageable);
    
    list.forEach(e-> System.out.println(e));
    

    4.2.3 分页+排序

    Sort sort = new Sort(Sort.Direction.DESC,"age");
    /**
     * page:第几页(0就是第1页)
     * size:每页条数
     * sort:排序对象
     */
    Pageable pageable = new PageRequest(0,10,sort);
    //分页对象
    Page<Employee> list = employeeRepository.findAll(pageable);
    
    list.forEach(e-> System.out.println(e));
    

    4.3 名称规则(根据条件进行查询)

    详细规则请查看文档

    /**
     * 根据规范(SpringDataJpa)写方法名,就可以进行查询
     * @param username
     * @return
     *  username =?
     */
    //根据用户名查询一个员工
    Employee findByUsername(String username);
    
    //用户名模糊查询 username like ?
    List<Employee> findByUsernameLike(String username);
    
    //用户名与邮件模糊查询 username like ? and email like ?
    List<Employee> findByUsernameLikeAndEmailLike(String username,String email);
    

    4.4 Query注解查询

    //根据用户名获取用户
    @Query("select o from Employee o where o.username =?1")
    Employee query01(String username);
    
    //用户名与邮件模糊查询 username like ? and email like ?
    @Query("select o from Employee o where o.username  like ?1 and o.email like ?2")
    List<Employee> query02(String username,String email);
    //    @Query("select o from Employee o where o.username  like :username and o.email like :email")
    //    List<Employee> query02(@Param("username") String username,@Param("email")  String email);
    
    //直接写原生的SQL
    @Query(nativeQuery=true,value="select * from employee")
    List<Employee> query03();
    

    五.JpaSpecificationExecutor

    • 是一个JPA的规范执行者
    • JPA2.0提供的Criteria API的使用封装
    • 需要咱们的的repository继承JpaSpecificationExecutor接口
    interface EmployeeRepository extends JpaRepository<Employee,Long>,JpaSpecificationExecutor<Employee>
    

    5.1 最简单的查询

    @Test
    public void testJpaSpecificationExecutor01() throws Exception{
        /**
         * 这里的查询我们需要自己去定义规则:Specification
         */
        List<Employee> list = employeeRepository.findAll(new Specification<Employee>() {
            /**
             * 这个方法就是帮咱们创建规则的方法,只要把这个方法搞定,咱们就可以完成查询了
             * @param root(根) : 代表了可以查询和操作的实体对象的根
             *                可以帮助我们获取到实体对应的字段
             * @param query(查询) : 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
             *                  还可以支持and ,or的功能
             * @param cb :用来构建CriteriaQuery的构建器对象(相当于条件或者说条件组合)
             *                  主要判断关系(和这个字段是相等,大于,小于like等)
             *                  支持 and,or的功能
             * @return Predicate:表明; 阐明; 断言
             *          你把它当成  where username like ? and email like ? and age > ? ...
             */
            @Override
            public Predicate toPredicate(Root<Employee> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
                //1.拿到Employee中的username字段
                Path usernamePath = root.get("username");
                //2.加上字段的判断关系
                // 参数1:字段(表达式)  2.值
                Predicate p1 = cb.like(usernamePath, "%1%");
                return p1;
            }
        });
    
        list.forEach(e-> System.out.println(e));
    }
    

    5.2 多个条件查询

    @Test
    public void testJpaSpecificationExecutor02() throws Exception{
        //Specification:查询规则
        List<Employee> list = employeeRepository.findAll(new Specification<Employee>() {
            // root:拿到字段(表达式)  cb:设置条件(>,<,=,like),and/or
            @Override
            public Predicate toPredicate(Root<Employee> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
                //拿到username并设置条件
                Path usernamePath = root.get("username");
                Predicate p1 = cb.like(usernamePath, "%1%");
                //拿到email并设置条件
                Path emailPath = root.get("email");
                Predicate p2 = cb.like(emailPath, "%2%");
                //拿到age并设置条件 gt/lt:大于/小于   ge/le:大于等于/小等等于
                Path agePath = root.get("age");
                Predicate p3 = cb.gt(agePath, 18);
                //把条件结合起来
                return cb.and(p1, p2, p3);
            }
        });
    
        list.forEach(e-> System.out.println(e));
    }
    

    5.3 查询+分页+排序

    /**
     * 高级查询加分页
     * @throws Exception
     */
    @Test
    public void testJpaSpecificationExecutor03() throws Exception{
            //创建一个分页对象
            Pageable pageable = new PageRequest(1,10);
            //分页+高级查询
            Page<Employee> page = employeeRepository.findAll(new Specification<Employee>() {
                @Override
                public Predicate toPredicate(Root<Employee> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
                    Path usernamePath = root.get("username");
                    return cb.like(usernamePath, "%1%");
                }
            }, pageable);
            page.forEach(e->System.out.println(e));
    }
    
    /**
     * 高级查询加分页+排序
     * @throws Exception
     */
    @Test
    public void testJpaSpecificationExecutor04() throws Exception{
        Sort sort = new Sort(Sort.Direction.DESC,"age");
        //创建一个分页对象
        Pageable pageable = new PageRequest(0,10,sort);
        //分页+高级查询
        Page<Employee> page = employeeRepository.findAll(new Specification<Employee>() {
            @Override
            public Predicate toPredicate(Root<Employee> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
                Path usernamePath = root.get("username");
                return cb.like(usernamePath, "%1%");
            }
        }, pageable);
        page.forEach(e->System.out.println(e));
    }
    

    六.jpa-spec

    6.1 简单查询

    注意:导的是:import com.github.wenhao.jpa.Specifications;

    //jpa-spec
    //完成咱们的简单查询 username like ?
    @Test
    public void testJpaSpec01() throws Exception{
        Specification<Employee> spec = Specifications.<Employee>and()
                .like("username", "%1%")
                .build();
        List<Employee> list = employeeRepository.findAll(spec);
        list.forEach(e-> System.out.println(e));
    }
    

    6.2 多条件查询

    //jpa-spec
    //完成咱们的简单查询 username like ? and email like ? and age>?
    @Test
    public void testJpaSpec02() throws Exception{
        Specification<Employee> spec = Specifications.<Employee>and()
                .like("username", "%1%")
                .like("email","%2%")
                .gt("age",18)
                .build();
        List<Employee> list = employeeRepository.findAll(spec);
        list.forEach(e-> System.out.println(e));
    }
    

    6.3 多条件+分页

    //jpa-spec
    //完成咱们的简单查询 username like ? + 分页 + 排序
    @Test
    public void testJpaSpec03() throws Exception{
        //创建排序对象
        Sort sort = new Sort(Sort.Direction.DESC,"age");
        //创建分页对象
        Pageable pageable = new PageRequest(0,10,sort);
        //规则对象(查询条件)
        Specification<Employee> spec = Specifications.<Employee>and()
                .like("username", "%1%")
                .build();
        //功能执行
        Page<Employee> page = employeeRepository.findAll(spec, pageable);
    
        page.forEach(e-> System.out.println(e));
    }
    

    七.Query抽取

    • Query是咱们的查询对象

    7.1 BaseQuery

    • 有经验的人都会创建父类
      • 方便扩展
      • 公共的代码
      • 制定规范
    • 目前咱们Query需要做的
      • 四个字段(currrentPage,pageSize,orderType,orderName)
      • 让每个子类都有一个:createSpec()
      • 创建一个order对象
      • 解决了传过来的是当前页从1开始(SpringDataJpa是从0开始计算)
    /**
     * 父类的作用:
     *   1.提供一些公共的属性的方法(少写代码)
     *   2.对子类形成相应的规范
     *   3.为了以后代码的扩展性
     */
    public abstract class BaseQuery {
    
        //分页 -> 当前第几页
        private int currentPage=1;
        //分页 -> 每页条数
        private int pageSize=10;
        //排序 -> 排序的类型 true(DESC)/false(ASC)
        private boolean orderType;
        //排序 -> 排序的字段 -> 如果这个字段为null,就代表不排序
        private String orderName;
    
        //创建排序对象
        public Sort createSort(){
            if(StringUtils.isNotBlank(orderName)){
                //orderName有值才做排序
                Sort sort = new Sort(orderType?Sort.Direction.DESC:Sort.Direction.ASC,orderName);
                return sort;
            }
            return null;
        }
        //要求只要继承了我,就必需有一个方法叫:createSpec()
        public abstract Specification createSpec();
    
        public int getJpaPage() {
            return currentPage-1;
        }
    
       //getter,setter....
       
    }
    

    7.2 EmployeeQuery

    • 设置当前对应的Domain的特有查询字段
    • 实现 createSpec()
    /**
     * 员工查询
     */
    public class EmployeeQuery extends BaseQuery {
    
        //用户名
        private String username;
        //邮件
        private String email;
        //年龄
        private Integer age;
    
        //查询的规则应该在查询对象中来创建
        @Override
        public Specification createSpec(){
            Specification<Employee> specification = Specifications.<Employee>and()
                    .like(StringUtils.isNotBlank(username), "username", "%" + username + "%")
                    .like(StringUtils.isNotBlank(email), "email", "%" + email + "%")
                    .gt(age != null, "age", age)
                    .build();
            return specification;
        }
    
        //getter,setter...
    }
    
    

    7.3 测试

    /**
     * 有Query的查询
     * @throws Exception
     */
    @Test
    public void testJpaSpec04() throws Exception{
        //以后咱们的查询数据是从前台传过来的,就会生成EmployeeQuery对象
        EmployeeQuery query = new EmployeeQuery();
    //        query.setUsername("1");
    //        query.setEmail("2");
    //        query.setAge(18);
        query.setOrderName("age");
        query.setOrderType(true);
    
        //创建排序对象
        Sort sort = query.createSort();
        //创建分页对象(分页对象从前台传过来)
        Pageable pageable = new PageRequest(query.getJpaPage(),query.getPageSize(),sort);
        //规则对象(查询条件)
        Specification<Employee> spec = query.createSpec();
        //功能执行
        Page<Employee> page = employeeRepository.findAll(spec, pageable);
        page.forEach(e-> System.out.println(e));
    }
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  • 原文地址:https://www.cnblogs.com/xiaoruirui/p/11650089.html
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