文章参考了：https://blog.csdn.net/long476964/article/details/79677526 。该文章介绍了 Example 类的用法（中文不好看过来）。
SpringDataJPA官方文档：https://docs.spring.io/spring-data/jpa/docs/2.0.9.RELEASE/reference/html/#query-by-example （英文大佬移步这里）
spring data jpa Example条件分页查询 实例
public Result listPageClaimAccount( String userId ,int pageNo ,int pageSize ,ClaimAccount claimAccount ){
if ( pageNo <=0 ) pageNo=1;
if ( pageSize <=0 ) pageSize=1;
pageNo-- ; //JPA的page参数从0开始
try {
Pageable pageable = PageRequest.of(pageNo, pageSize, new Sort(Sort.Direction.DESC, "id") );
Example<ClaimAccount> example = Example.of( claimAccount );
Page<ClaimAccount> pageResult = claimAccountRepository.findAll( example, pageable );
return Result.success( pageResult );
}catch ( Exception e ){
e.printStackTrace();
log.error("数据库操作出现错误",e);
return Result.fail("数据库操作出现错误");
}
}JpaRepository 抽象接口继承了一大堆接口。上面代码中实际调用的是
org.springframework.data.repository.query.QueryByExampleExecutor 接口中定义的 findAll 方法
/**
* Returns a {@link Page} of entities matching the given {@link Example}. In case no match could be found, an empty
* {@link Page} is returned.
*
* @param example must not be {@literal null}.
* @param pageable can be {@literal null}.
* @return a {@link Page} of entities matching the given {@link Example}.
*/
<S extends T> Page<S> findAll(Example<S> example, Pageable pageable);org.springframework.data.repository.query.QueryByExampleExecutor
/**
* Interface to allow execution of Query by Example {@link Example} instances.
*
* @param <T>
* @author Mark Paluch
* @author Christoph Strobl
* @since 1.12
*/
public interface QueryByExampleExecutor<T> {org.springframework.data.domain.Example 的 of(T probe) 方法默认用的 等于 的比较器，会将参数的非空属性 作为where部分的相等判断参数
/**
* Support for query by example (QBE). An {@link Example} takes a {@code probe} to define the example. Matching options
* and type safety can be tuned using {@link ExampleMatcher}.
*
* @author Christoph Strobl
* @author Mark Paluch
* @author Oliver Gierke
* @param <T> the type of the probe.
* @since 1.12
*/
public interface Example<T> {
/**
* Create a new {@link Example} including all non-null properties by default.
*
* @param probe must not be {@literal null}.
* @return
*/
static <T> Example<T> of(T probe) {
return new TypedExample<>(probe, ExampleMatcher.matching());
}代码运行后的控制台输出（info 级别）
Hibernate:
select
claimaccou0_.id as id1_0_,
claimaccou0_.case_service_man_phone as case_ser2_0_,
claimaccou0_.create_by as create_b3_0_,
claimaccou0_.create_date as create_d4_0_,
claimaccou0_.insurance_company as insuranc5_0_,
claimaccou0_.insurance_date as insuranc6_0_,
claimaccou0_.insurance_man as insuranc7_0_,
claimaccou0_.insurance_man_phone as insuranc8_0_,
claimaccou0_.insurance_reason as insuranc9_0_,
claimaccou0_.insurance_type as insuran10_0_,
claimaccou0_.loss_amount as loss_am11_0_,
claimaccou0_.loss_institution as loss_in12_0_,
claimaccou0_.pay_amount as pay_amo13_0_,
claimaccou0_.pay_date as pay_dat14_0_,
claimaccou0_.pay_progress as pay_pro15_0_,
claimaccou0_.remark as remark16_0_,
claimaccou0_.report_date as report_17_0_,
claimaccou0_.report_no as report_18_0_,
claimaccou0_.update_by as update_19_0_,
claimaccou0_.update_date as update_20_0_
from
a_claim_account claimaccou0_
where
claimaccou0_.insurance_company=?
and claimaccou0_.loss_institution=?
and claimaccou0_.insurance_type=?
order by
claimaccou0_.id desc limit ?
Hibernate:
select
count(claimaccou0_.id) as col_0_0_
from
a_claim_account claimaccou0_
where
claimaccou0_.insurance_company=?
and claimaccou0_.loss_institution=?
and claimaccou0_.insurance_type=?