import org.elasticsearch.transport.TransportRequestHandler; //导入依赖的package包/类
@Override
public List<TransportInterceptor> getTransportInterceptors(NamedWriteableRegistry namedWriteableRegistry,
                                                           ThreadContext threadContext) {
    return Collections.singletonList(new TransportInterceptor() {
        @Override
        public <T extends TransportRequest> TransportRequestHandler<T> interceptHandler(String action, String executor,
                                                                                    boolean forceExecution,
                                                                                    TransportRequestHandler<T> actualHandler) {
            return instance.interceptHandler(action, executor, forceExecution, actualHandler);
        }

        @Override
        public AsyncSender interceptSender(AsyncSender sender) {
            return instance.interceptSender(sender);
        }
    });
}
 

import org.elasticsearch.transport.TransportRequestHandler; //导入依赖的package包/类
@Override
public <T extends TransportRequest> TransportRequestHandler<T> interceptHandler(String action, String executor,
                                                                                boolean forceExecution,
                                                                                TransportRequestHandler<T> actualHandler) {
    for (TransportInterceptor interceptor : this.transportInterceptors) {
        actualHandler = interceptor.interceptHandler(action, executor, forceExecution, actualHandler);
    }
    return actualHandler;
}
 

import org.elasticsearch.transport.TransportRequestHandler; //导入依赖的package包/类
SearchGuardRequestHandler(String action, 
        final TransportRequestHandler<T> actualHandler, 
        final ThreadPool threadPool,
        final BackendRegistry backendRegistry,
        final AuditLog auditLog,
        final PrincipalExtractor principalExtractor,
        final InterClusterRequestEvaluator requestEvalProvider,
        final ClusterService cs,
        final SslExceptionHandler sslExceptionHandler) {
    super(action, actualHandler, threadPool, principalExtractor, sslExceptionHandler);
    this.backendRegistry = backendRegistry;
    this.auditLog = auditLog;
    this.requestEvalProvider = requestEvalProvider;
    this.cs = cs;
}
 

import org.elasticsearch.transport.TransportRequestHandler; //导入依赖的package包/类
public SearchGuardSSLRequestHandler(String action, TransportRequestHandler<T> actualHandler, 
        ThreadPool threadPool, final PrincipalExtractor principalExtractor, final SslExceptionHandler errorHandler) {
    super();
    this.action = action;
    this.actualHandler = actualHandler;
    this.threadPool = threadPool;
    this.principalExtractor = principalExtractor;
    this.errorHandler = errorHandler;
}
 

import org.elasticsearch.transport.TransportRequestHandler; //导入依赖的package包/类
@Override
public <T extends TransportRequest> TransportRequestHandler<T> interceptHandler(String action, String executor,
                                                                                boolean forceExecution,
                                                                                TransportRequestHandler<T> actualHandler) {
    return new InterceptingRequestHandler<>(action, actualHandler);
}
 

import org.elasticsearch.transport.TransportRequestHandler; //导入依赖的package包/类
InterceptingRequestHandler(String action, TransportRequestHandler<T> requestHandler) {
    this.requestHandler = requestHandler;
    this.action = action;
}
 

import org.elasticsearch.transport.TransportRequestHandler; //导入依赖的package包/类
public <T extends TransportRequest> SearchGuardRequestHandler<T> getHandler(String action, 
        TransportRequestHandler<T> actualHandler) {
    return new SearchGuardRequestHandler<T>(action, actualHandler, threadPool, backendRegistry, auditLog, 
            principalExtractor, requestEvalProvider, cs, sslExceptionHandler);
}
 

import org.elasticsearch.transport.TransportRequestHandler; //导入依赖的package包/类
@Override
public <T extends TransportRequest> TransportRequestHandler<T> interceptHandler(String action, String executor, boolean forceExecution,
        TransportRequestHandler<T> actualHandler) {
    return new SearchGuardSSLRequestHandler<T>(action, actualHandler, threadPool, principalExtractor, errorHandler);
}
 

import org.elasticsearch.transport.TransportRequestHandler; //导入依赖的package包/类
protected void messageReceivedDecorate(final T request, final TransportRequestHandler<T> actualHandler, final TransportChannel transportChannel, Task task) throws Exception {
    actualHandler.messageReceived(request, transportChannel, task);
}