Spring Data Jpa接口简介

Repository接口

public interface Repository<T, ID> {....}

提供了按方法名称的查询方式；

提供了@Query的查询方式

可能遇到的错误：

1）Caused by: javax.persistence.TransactionRequiredException: Executing an update/delete query（手动加@Transactional解决）

2）如果test方法里加事务注解数据不更新的话，还需要手动加@Rollback（false）解决，自己测试的时候，只加了一个@Transactional就更新成功了.

CrudRepository接口

public interface CrudRepository<T, ID> extends Repository<T, ID> {....}

    public void test1 () {
        JpaUser jpaUser = new JpaUser("名称1","地址1",,,);
        Optional<JpaUser> optionalT = userRespotory.findById() ;
        Iterable<JpaUser> list = userRespotory.findAll();
        userRespotory.delete(jpaUser);
        userRespotory.save(jpaUser);//保存or更新

PagingAndSortingRepository接口

public interface PagingAndSortingRepository<T, ID> extends CrudRepository<T, ID> {
    Iterable<T> findAll(Sort var1);
    Page<T> findAll(Pageable var1);
}

//测试sort   

 public void test1 () {
        JpaUser jpaUser = new JpaUser("名称1","地址1",,,);

        Sort sort = new Sort(Sort.Direction.DESC,"id");

        Iterable<JpaUser> list = userRespotory.findAll(sort);

//测试page

    public void test1 () {
        JpaUser jpaUser = new JpaUser("名称1","地址1",10,20,100);
        Pageable pageable = PageRequest.of(0, 2);
        Page<JpaUser> page = userRespotory.findAll(pageable);

        System.out.println(page.getTotalElements());//总条数
        System.out.println(page.getTotalPages());//总页数
        System.out.println(page.getContent());//当前页集合
//测试分页+排序

    public void test1 () {
        JpaUser jpaUser = new JpaUser("名称1","地址1",10,20,100);
        Pageable pageable = PageRequest.of(1, 2,Sort.Direction.DESC,"id","age1");
        Page<JpaUser> page = userRespotory.findAll(pageable);

        System.out.println(page.getTotalElements());//总条数
        System.out.println(page.getTotalPages());//总页数
        System.out.println(page.getContent());//当前页集合

JpaRepository接口

public interface JpaRepository<T, ID> extends PagingAndSortingRepository<T, ID>, QueryByExampleExecutor<T> {....}

JpaSpecificationExecutor接口

public interface JpaSpecificationExecutor<T> {
    Optional<T> findOne(@Nullable Specification<T> var1);

    List<T> findAll(@Nullable Specification<T> var1);

    Page<T> findAll(@Nullable Specification<T> var1, Pageable var2);

    List<T> findAll(@Nullable Specification<T> var1, Sort var2);

    long count(@Nullable Specification<T> var1);
}

可多条件查询，分页和排序，和以上接口联合使用。

public interface UserSpecificationExcutor extends JpaRepository<JpaUser,Integer> , JpaSpecificationExecutor<JpaUser> {....}

 @Autowired
    UserSpecificationExcutor userSpecificationExcutor;
    @Test
    public void test1 () {
        Specification<JpaUser> specification = new Specification<JpaUser>() {
            @Override
            public Predicate toPredicate(Root<JpaUser> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                Predicate predicate = criteriaBuilder.equal(root.get("name"), "名称1");
                List<Predicate> list = new ArrayList<>();
                list.add(predicate);
                predicate = criteriaBuilder.equal(root.get("age1"), );
                list.add(predicate);

                return criteriaBuilder.and(list.toArray(new Predicate[list.size()]));
            }
        };
        List<JpaUser> list = userSpecificationExcutor.findAll(specification);
        System.out.println(list);

一对对关联关系role-user

@Test
    public void test1 () {
        JpaUser jpaUser = new JpaUser("jpaName","diz地址" , , );
        jpaUser.setId();
        UserRole userRole = new UserRole();
        userRole.setName("role名字");
        userRole.setName1("role名字");
        userRole.setName2("role名字");
        userRole.getUserSet().add(jpaUser);
        jpaUser.setUserRole(userRole);
        userSpecificationExcutor.save(jpaUser);

package com.example.zs.springDataJpa;

import javax.persistence.*;
import java.util.HashSet;
import java.util.Set;

@Entity
@Table(name="t_role")
public class UserRole {
    @Id( )
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="id")
    private Integer id ;
    @Column(name="name")
    private String name;
    @Column(name="name1")
    private String name1;
    @Column(name="name2")
    private String name2;
    @OneToMany(mappedBy="userRole")
    private Set<JpaUser> userSet = new HashSet<>();

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Set<JpaUser> getUserSet() {
        return userSet;
    }

    public void setUserSet(Set<JpaUser> userSet) {
        this.userSet = userSet;
    }

    public String getName1() {
        return name1;
    }

    public void setName1(String name1) {
        this.name1 = name1;
    }

    public String getName2() {
        return name2;
    }

    public void setName2(String name2) {
        this.name2 = name2;
    }
}

package com.example.zs.springDataJpa;

import javax.persistence.*;

@Entity
@Table(name="t_user")
public class JpaUser {
    @Column(name="name")
    private String name ;
    @Column(name="address")
    private String address ;
    @Column(name="id")
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id ;
    @Column(name="age1")
    private Integer age ;
    @Column(name="age11")
    private  Integer age1 ;
    @ManyToOne(cascade = CascadeType.PERSIST)
    @JoinColumn(name="roleFK")
    private UserRole userRole;

    public JpaUser(String name, String address, Integer age, Integer age1 ) {
        this.name = name;
        this.address = address;
        this.age = age;
        this.age1 = age1;
//        this.id = id;
    }

    public JpaUser() {
    }

    @Override
    public String toString() {
        return "JpaUser{" +
                "name='" + name + '\'' +
                ", address='" + address + '\'' +
                ", id=" + id +
                ", age=" + age +
                ", age1=" + age1 +
                '}';
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Integer getAge1() {
        return age1;
    }

    public void setAge1(Integer age1) {
        this.age1 = age1;
    }

    public UserRole getUserRole() {
        return userRole;
    }

    public void setUserRole(UserRole userRole) {
        this.userRole = userRole;
    }
}

public interface UserSpecificationExcutor extends JpaRepository<JpaUser,Integer> , JpaSpecificationExecutor<JpaUser> {
}