Spring boot使用Jpa的@Modifying的clearAutomatically = true的作用

1、代码示例 

@Modifying(clearAutomatically = true)
@Query(value = "update customer_adviser set  " +
        " auditStatus = ?1, "+
        " optUserCode = ?3,"+
        " optUserName = ?4 "+
        " where id = ?2", nativeQuery = true)
int updateCustomerAdviserStatusByID(int auditResult,Long id, String optUserCode, String optUserName);

2、详解

    点击@Modifying，进入这个注解(源码，已经贴在文章后面)，我们能看到，它是指可以清除底层持久化上下文，即entityManager这个类；Jpa底层实现会有一级缓存，也就是在更新完数据库后，如果后面去用这个对象，你再去查这个对象，这个对象是在一级缓存，但是并没有跟数据库同步，此时使用clearAutomatically=true，就会刷新Hibernate的一级缓存， 否则在同一接口中，更新一个对象，接着查询这个对象，那么查出来的这个对象还是之前的没有更新前的状态。

Defines whether we should clear the underlying persistence context after executing the modifying query.

翻译：

定义在执行修改查询后是否应该清除底层持久化上下文。

/*
 * Copyright 2008-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
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package org.springframework.data.jpa.repository;
 
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
 
/**
 * Indicates a method should be regarded as modifying query.
 * 
 * @author Oliver Gierke
 * @author Christoph Strobl
 * @author Nicolas Cirigliano
 */
@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.METHOD, ElementType.ANNOTATION_TYPE })
@Documented
public @interface Modifying {
 
	/**
	 * Defines whether we should flush the underlying persistence context before executing the modifying query.
	 * 
	 * @return
	 */
	boolean flushAutomatically() default false;
 
	/**
	 * Defines whether we should clear the underlying persistence context after executing the modifying query.
	 * 
	 * @return
	 */
	boolean clearAutomatically() default false;
}