依赖

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
</dependency>

报错

Caused by: org.apache.http.ContentTooLongException: entity content is too long [143914703] for the configured buffer limit [104857600]
	at org.elasticsearch.client.HeapBufferedAsyncResponseConsumer.onEntityEnclosed(HeapBufferedAsyncResponseConsumer.java:76)
	at org.apache.http.nio.protocol.AbstractAsyncResponseConsumer.responseReceived(AbstractAsyncResponseConsumer.java:137)
	at org.apache.http.impl.nio.client.MainClientExec.responseReceived(MainClientExec.java:315)
	at org.apache.http.impl.nio.client.DefaultClientExchangeHandlerImpl.responseReceived(DefaultClientExchangeHandlerImpl.java:151)
	at org.apache.http.nio.protocol.HttpAsyncRequestExecutor.responseReceived(HttpAsyncRequestExecutor.java:315)
	at org.apache.http.impl.nio.DefaultNHttpClientConnection.consumeInput(DefaultNHttpClientConnection.java:255)
	at org.apache.http.impl.nio.client.InternalIODispatch.onInputReady(InternalIODispatch.java:81)
	at org.apache.http.impl.nio.client.InternalIODispatch.onInputReady(InternalIODispatch.java:39)
	at org.apache.http.impl.nio.reactor.AbstractIODispatch.inputReady(AbstractIODispatch.java:114)
	at org.apache.http.impl.nio.reactor.BaseIOReactor.readable(BaseIOReactor.java:162)
	at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvent(AbstractIOReactor.java:337)
	at org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvents(AbstractIOReactor.java:315)
	at org.apache.http.impl.nio.reactor.AbstractIOReactor.execute(AbstractIOReactor.java:276)
	at org.apache.http.impl.nio.reactor.BaseIOReactor.execute(BaseIOReactor.java:104)
	at org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor$Worker.run(AbstractMultiworkerIOReactor.java:591)
	at java.lang.Thread.run(Thread.java:748)

报错原因

在ElasticsearchRestTemplate中使用了RequestIOptions.DEFAULT

解决办法

查看了源码HttpAsyncResponseConsumerFactory是没有通过Spring容器注入的，所以没办法通过声明Bean来覆盖，那么我想到的办法是通过反射来修改RequestIOptions中的HttpAsyncResponseConsumerFactory。

因为我的项目使用的是SpringMVC，那么我可以在运行时来修改，即第一次接口调用的时候来修改，这个时候相关的类已经全部加载完毕。那么我可以使用SpringMVC的拦截器HandleInceptor的preHandle()

以下就为我的配置，修改最大每次查询上限为300MB

@Configuration
public class MvcConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        //设置ElasticsearchRestTemplate查询的最大值为300MB 默认为100MB
        registry.addInterceptor(new HandlerInterceptor() {
            private boolean isSetBuffer = false;

            @Override
            public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
                //已经设置过
                if (isSetBuffer) {
                    return true;
                }
                //设置es查询buffer大小
                RequestOptions requestOptions = RequestOptions.DEFAULT;
                Class<? extends RequestOptions> aClass = requestOptions.getClass();
                Field aDefault = aClass.getDeclaredField("httpAsyncResponseConsumerFactory");
                aDefault.setAccessible(true);
                //去除final
                Field modifiersField = Field.class.getDeclaredField("modifiers");
                modifiersField.setAccessible(true);
                modifiersField.setInt(aDefault, aDefault.getModifiers() & ~Modifier.FINAL);

                //设置默认的工厂
                aDefault.set(requestOptions, new HttpAsyncResponseConsumerFactory() {
                    /**
                     * Creates the {@link HttpAsyncResponseConsumer}, called once per request attempt.
                     */
                    @Override
                    public HttpAsyncResponseConsumer<HttpResponse> createHttpAsyncResponseConsumer() {
                        //300MB
                        return new HeapBufferedAsyncResponseConsumer(3 * 100 * 1024 * 1024);
                    }
                });
                //标记
                isSetBuffer = true;

                return true;
            }
        });
    }
}