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SpringDataJPA的四种查询方式

• 借助接口中的定义好的方法完成查询
• jpql的查询方式
• sql语句的查询
• 方法名称规则查询

示例

创建Maven工程并导入依赖

   
       
    
     4.0.0
        
    
     pers.zhang
        
    
     spirngdata_jpa
        
    
     1.0-SNAPSHOT
        
            
     
      4.2.4.RELEASE
             
     
      5.0.7.Final
             
     
      1.6.6
             
     
      1.2.12
             
     
      0.9.1.2
             
     
      5.1.6
         
        
            
             
                 
      
       junit
                  
      
       junit
                  
      
       4.9
                  
      
       test
              
             
             
                 
      
       org.aspectj
                  
      
       aspectjweaver
                  
      
       1.6.8
              
             
                 
      
       org.springframework
                  
      
       spring-aop
                  
      
       ${spring.version}
              
             
                 
      
       org.springframework
                  
      
       spring-context
                  
      
       ${spring.version}
              
             
                 
      
       org.springframework
                  
      
       spring-context-support
                  
      
       ${spring.version}
              
             
                 
      
       org.springframework
                  
      
       spring-orm
                  
      
       ${spring.version}
              
             
                 
      
       org.springframework
                  
      
       spring-beans
                  
      
       ${spring.version}
              
             
                 
      
       org.springframework
                  
      
       spring-core
                  
      
       ${spring.version}
              
             
             
             
                 
      
       org.hibernate
                  
      
       hibernate-core
                  
      
       ${hibernate.version}
              
             
                 
      
       org.hibernate
                  
      
       hibernate-entitymanager
                  
      
       ${hibernate.version}
              
             
                 
      
       org.hibernate
                  
      
       hibernate-validator
                  
      
       5.2.1.Final
              
             
             
             
                 
      
       c3p0
                  
      
       c3p0
                  
      
       ${c3p0.version}
              
             
             
             
                 
      
       log4j
                  
      
       log4j
                  
      
       ${log4j.version}
              
             
                 
      
       org.slf4j
                  
      
       slf4j-api
                  
      
       ${slf4j.version}
              
             
                 
      
       org.slf4j
                  
      
       slf4j-log4j12
                  
      
       ${slf4j.version}
              
             
             
                 
      
       mysql
                  
      
       mysql-connector-java
                  
      
       ${mysql.version}
              
             
                 
      
       org.springframework.data
                  
      
       spring-data-jpa
                  
      
       1.9.0.RELEASE
              
             
                 
      
       org.springframework
                  
      
       spring-test
                  
      
       4.2.4.RELEASE
              
             
             
                 
      
       javax.el
                  
      
       javax.el-api
                  
      
       2.2.4
              
             
                 
      
       org.glassfish.web
                  
      
       javax.el
                  
      
       2.2.4
              
             
         
    
   

配置文件：applicationContext.xml

创建表并准备数据

实体Customer

package pers.zhang.entity;/** * @author zhang * @date 2019/12/15 - 22:10 */import javax.persistence.*;/** *  1.实体类和表的映射关系 *      @Entity *      @Table *  2.类中属性和表中字段的映射关系 *      @Id *      @GeneratedValue *      @Colum */@Entity //声明实体类@Table(name="cst_customer") //建立实体类和表的映射关系public class Customer {
       @Id//声明当前私有属性为主键    @GeneratedValue(strategy= GenerationType.IDENTITY) //配置主键的生成策略    @Column(name="cust_id") //指定和表中cust_id字段的映射关系    private Long custId;    @Column(name="cust_name") //指定和表中cust_name字段的映射关系    private String custName;    @Column(name="cust_source")//指定和表中cust_source字段的映射关系    private String custSource;    @Column(name="cust_industry")//指定和表中cust_industry字段的映射关系    private String custIndustry;    @Column(name="cust_level")//指定和表中cust_level字段的映射关系    private String custLevel;    @Column(name="cust_address")//指定和表中cust_address字段的映射关系    private String custAddress;    @Column(name="cust_phone")//指定和表中cust_phone字段的映射关系    private String custPhone;    public Long getCustId() {
           return custId;    }    public void setCustId(Long custId) {
           this.custId = custId;    }    public String getCustName() {
           return custName;    }    public void setCustName(String custName) {
           this.custName = custName;    }    public String getCustSource() {
           return custSource;    }    public void setCustSource(String custSource) {
           this.custSource = custSource;    }    public String getCustIndustry() {
           return custIndustry;    }    public void setCustIndustry(String custIndustry) {
           this.custIndustry = custIndustry;    }    public String getCustLevel() {
           return custLevel;    }    public void setCustLevel(String custLevel) {
           this.custLevel = custLevel;    }    public String getCustAddress() {
           return custAddress;    }    public void setCustAddress(String custAddress) {
           this.custAddress = custAddress;    }    public String getCustPhone() {
           return custPhone;    }    public void setCustPhone(String custPhone) {
           this.custPhone = custPhone;    }    @Override    public String toString() {
           return "Customer{" +                "custId=" + custId +                ", custName='" + custName + '\'' +                ", custSource='" + custSource + '\'' +                ", custIndustry='" + custIndustry + '\'' +                ", custLevel='" + custLevel + '\'' +                ", custAddress='" + custAddress + '\'' +                ", custPhone='" + custPhone + '\'' +                '}';    }}

Dao层接口：

package pers.zhang.dao;import org.springframework.data.jpa.repository.JpaRepository;import org.springframework.data.jpa.repository.JpaSpecificationExecutor;import org.springframework.data.jpa.repository.Modifying;import org.springframework.data.jpa.repository.Query;import org.springframework.transaction.annotation.Transactional;import pers.zhang.entity.Customer;import java.util.List;/** * @author zhang * @date 2019/12/15 - 22:22 *//** * 符合SpringDataJpa的dao层接口规范 *      JpaRepository
   <操作的实体类类型， 实体类中主键属性的类型>
     *          封装了基本CRUD操作 *      JpaSpecificationExecutor
    <操作的实体类类型>
      *          封装了复杂查询（分页） */public interface CustomerDao extends JpaRepository
     
      , JpaSpecificationExecutor
      
        {
       /*        二：Jpql的查询方式：            jpql：jpa query Language            特点：语法或关键字和sql语句类似，查询的是类和类中的属性            需要将JPQL语句配置到借口的方法上             1.特有的查询：需要在dao接口上配置方法             2.在新添加的方法上，使用注解的形式配置Jpql查询语句             3.注解：@Query     */    /*        根据名称查询客户:使用Jpql查询            from Customer where custName=?     */    @Query(value = "from Customer where custName = ?1")    public Customer findJpql(String custName);    /*        根据客户名称和id查询客户：使用Jpql查询            from Customer where custName = ?1 and custId = ?2     */    @Query(value = "from Customer where custName = ?1 and custId = ?2")    public Customer findCustNameAndId(String custName, Long custId);    /*        根据id更新客户：使用Jpql查询            使用@Modifying声明此方法是用于更新操作            调用时使用@Transactional添加事务     */    @Query(value = "update Customer set custName = ?1 where custId = ?2")    @Modifying    public void updateById(String custName, Long custId);    /*        三：sql语句的查询：            1. 特有的查询：需要在dao接口上配置方法            2.在新添加的方法上，使用注解的形式配置sql查询语句            3.注解：@Query                value：jpql语句 | sql语句                nativeQuery：false | true ：是否使用本地查询     */    /*        查询所有：使用sql的形式查询            sql: select * from cst_customer;     */    @Query(value = "select * from cst_customer", nativeQuery = true)    public List
       
         findALL();    /*        根据名称模糊查询:sql            sql： select * from cst_customer where cust_name like ?     */    @Query(value = "select * from cst_customer where cust_name like ?1", nativeQuery = true)    public List
        
          findListByName(String name); /* 四：方法名称规则查询 是对Jpql查询更加深入的一层封装 只需要按照SpringDataJpa提供的方法名称规则定义方法，不需要再去配置Jpql语句，完成查询 约定： findBy：查询 对象中的属性名（首字母大写）：查询的条件 1.根据属性名称进行完整匹配： findBy + 属性名称 2.模糊查询： findBy + 属性名称 + "查询方式（Like | isnull）" 3.多条件查询： findBy + 属性名称 + “查询方式” + “多条件的连接符（and | or）” + "属性名称" + “查询方式” 例如：根据姓名查询客户 findByCustName 根据姓名模糊查询 findByCustNameLike 根据姓名模糊查询和所属行业精准查询 findByCustNameLikeAndCustIndustry 在SpringDataJpa的运行阶段，会根据方法名称进行解析 findBy from xxx(实体类) 属性名称 where custName = */ public Customer findByCustName(String name); public List
         
           findByCustNameLike(String name); public Customer findByCustNameLikeAndCustIndustry(String name, String industry);}
         
        
       
      
     
    
   

借助接口中的定义好的方法完成查询

@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = "classpath:applicationContext.xml")public class mytest {
       @Autowired    private CustomerDao customerDao;    /*        根据id查询     */    @Test    public void testFindById(){
           Customer one = customerDao.findOne(2l);        System.out.println(one);    }    /*        save:保存或更新            如果传递的对象中没有id：保存            如果传递的对象中有id：根据id查询，然后更新数据     */    @Test    public void testSave(){
           Customer customer = new Customer();        customer.setCustName("三星");        customer.setCustAddress("思密达");        customerDao.save(customer);    }    /*        delete:根据id删除     */    @Test    public void testDelete(){
           customerDao.delete(7l);    }    /*        findAll：查询所有     */    @Test    public void testFindAll(){
           List
   
     all = customerDao.findAll();        for(Customer c : all)            System.out.println(c);    }        /*        count：统计查询     */    @Test    public void testCount(){
           long count = customerDao.count();        System.out.println(count);    }    /*        exists：判断主键为？的是否存在     */    @Test    public void testExists(){
           boolean exists = customerDao.exists(4L);        System.out.println(exists);    }    /*        getOne:根据id从数据库查询            @Transactional：保证getOne正常运行        与findOne的区别：            findOne:底层调用find()方法，立即加载            getOne：底层调用getReference()方法，延迟加载     */    @Test    @Transactional    public void testGetOne(){
           Customer one = customerDao.getOne(3L);        System.out.println(one);    }}
   

jpql的查询方式

@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = "classpath:applicationContext.xml")public class JpqlTest {
       @Autowired    private CustomerDao customerDao;    @Test    public void testFindByName(){
           Customer cusomer = customerDao.findJpql("万达");        System.out.println(cusomer);    }    @Test    public void testFindByNameAndId(){
           Customer customer = customerDao.findCustNameAndId("万达", 3L);        System.out.println(customer);    }    /*        测试Jpql的更新操作            springDataJpa中使用Jpql完成更新或删除操作                *需要手动添加事务的支持                *默认会在执行结束之后，回滚事务                    使用@Rollback取消自动回滚     */    @Test    @Transactional//更新和删除需要添加事务支持    @Rollback(value = false)    public void testUpdateNameById(){
           customerDao.updateById("万达万达", 3L);    }    }

sql语句的查询

@Test    public void testFindAllBySql(){
           List
   
     all = customerDao.findALL();        for(Object[] objects : all){
               System.out.println(Arrays.toString(objects));        }    }    @Test    public void testFindListByName(){
           List
    
      list = customerDao.findListByName("%万%");        for(Object[] objects : list){
               System.out.println(Arrays.toString(objects));        }    }
    
   

方法名称规则查询

@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = "classpath:applicationContext.xml")public class SimpleTest {
       //测试根据方法命名规则查询    @Autowired    private CustomerDao customerDao;    @Test    public void testFindByCustName(){
           Customer customer = customerDao.findByCustName("网易");        System.out.println(customer);    }            @Test    public void testFindByCustNameLike(){
           List
   
     list = customerDao.findByCustNameLike("%易");        for(Customer c : list)            System.out.println(c);    }    @Test    public void testFindByCustNameLikeAndCustIndustry(){
           Customer customer = customerDao.findByCustNameLikeAndCustIndustry("网%", "游戏");        System.out.println(customer);    }}
   

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