Java tutorial
/* * Copyright 2002-2019 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 * * https://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.integration.http.inbound; import java.io.PrintWriter; import java.io.StringWriter; import java.util.HashMap; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.expression.Expression; import org.springframework.expression.common.LiteralExpression; import org.springframework.expression.spel.support.StandardEvaluationContext; import org.springframework.http.RequestEntity; import org.springframework.http.server.ServletServerHttpRequest; import org.springframework.http.server.ServletServerHttpResponse; import org.springframework.messaging.Message; import org.springframework.util.Assert; import org.springframework.util.StringUtils; import org.springframework.validation.MapBindingResult; import org.springframework.web.servlet.ModelAndView; import org.springframework.web.servlet.View; import org.springframework.web.servlet.mvc.Controller; /** * Inbound HTTP endpoint that implements Spring's {@link Controller} interface to be used with a DispatcherServlet front * controller. * <p> * The {@link #setViewName(String) viewName} will be passed into the ModelAndView return value. * <p> * This endpoint will have request/reply behavior by default. That can be overridden by passing <code>false</code> to * the constructor. In the request/reply case, the core map will be passed to the view, and it will contain either the * reply Message or payload depending on the value of {@link #setExtractReplyPayload(boolean)} * (true by default, meaning just the payload). * The corresponding key in the map is determined by the {@link #replyKey} property (with a default of "reply"). * * @author Mark Fisher * @author Gary Russell * @author Artem Bilan * * @since 2.0 */ public class HttpRequestHandlingController extends HttpRequestHandlingEndpointSupport implements Controller { /** * The View model key for the error code. */ public static final String DEFAULT_ERROR_CODE = "spring.integration.http.handler.error"; /** * The View model key for reply. */ public static final String DEFAULT_REPLY_KEY = "reply"; /** * The View model key for errors. */ public static final String DEFAULT_ERRORS_KEY = "errors"; private Expression viewExpression; private StandardEvaluationContext evaluationContext; private String replyKey = DEFAULT_REPLY_KEY; private String errorsKey = DEFAULT_ERRORS_KEY; private String errorCode = DEFAULT_ERROR_CODE; public HttpRequestHandlingController() { this(true); } public HttpRequestHandlingController(boolean expectReply) { super(expectReply); } /** * Specify the view name. * @param viewName The view name. */ public void setViewName(String viewName) { Assert.isTrue(StringUtils.hasText(viewName), "View name must contain text"); this.viewExpression = new LiteralExpression(viewName); } /** * Specify the key to be used when adding the reply Message or payload to the core map (will be payload only unless * the value of {@link HttpRequestHandlingController#setExtractReplyPayload(boolean)} is <code>false</code>). The * default key is "reply". * @param replyKey The reply key. */ public void setReplyKey(String replyKey) { this.replyKey = (replyKey != null) ? replyKey : DEFAULT_REPLY_KEY; } /** * The key used to expose {@link org.springframework.validation.Errors} in the core, * in the case that message handling fails. Defaults to "errors". * @param errorsKey The key value to set. */ public void setErrorsKey(String errorsKey) { this.errorsKey = errorsKey; } /** * The error code to use to signal an error in the message handling. In the case of an error this code will be * provided in an object error to be optionally translated in the standard MVC way using a * {@link org.springframework.context.MessageSource}. * The default value is <code>spring.integration.http.handler.error</code>. Three arguments are provided: the * exception, its message and its stack trace as a String. * @param errorCode The error code to set. */ public void setErrorCode(String errorCode) { this.errorCode = errorCode; } /** * Specifies a SpEL expression to evaluate in order to generate the view name. * The EvaluationContext will be populated with the reply message as the root object, * @param viewExpression The view expression. */ public void setViewExpression(Expression viewExpression) { this.viewExpression = viewExpression; } @Override protected void onInit() { super.onInit(); this.evaluationContext = this.createEvaluationContext(); } /** * Handles the HTTP request by generating a Message and sending it to the request channel. If this gateway's * 'expectReply' property is true, it will also generate a response from the reply Message once received. */ @Override public final ModelAndView handleRequest(HttpServletRequest servletRequest, HttpServletResponse servletResponse) { ModelAndView modelAndView = new ModelAndView(); try { ServletServerHttpRequest request = prepareRequest(servletRequest); RequestEntity<Object> httpEntity = prepareRequestEntity(request); Message<?> replyMessage = doHandleRequest(servletRequest, httpEntity); ServletServerHttpResponse response = new ServletServerHttpResponse(servletResponse); if (replyMessage != null) { Object reply = setupResponseAndConvertReply(response, replyMessage); response.close(); modelAndView.addObject(this.replyKey, reply); } else { setStatusCodeIfNeeded(response, httpEntity); } if (this.viewExpression != null) { Object view; if (replyMessage != null) { view = this.viewExpression.getValue(this.evaluationContext, replyMessage); } else { view = this.viewExpression.getValue(this.evaluationContext); } if (view instanceof View) { modelAndView.setView((View) view); } else if (view instanceof String) { modelAndView.setViewName((String) view); } else { throw new IllegalStateException("view expression must resolve to a View or String"); } } } catch (Exception e) { MapBindingResult errors = new MapBindingResult(new HashMap<String, Object>(), "dummy"); PrintWriter stackTrace = new PrintWriter(new StringWriter()); e.printStackTrace(stackTrace); errors.reject(this.errorCode, new Object[] { e, e.getMessage(), stackTrace.toString() }, "A Spring Integration handler raised an exception while handling an HTTP request. " + "The exception is of type " + e.getClass() + " and it has a message: (" + e.getMessage() + ")"); modelAndView.addObject(this.errorsKey, errors); } return modelAndView; } }