Java tutorial
/* * $Id$ * * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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 * * 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 com.wxxr.nirvana.json; import com.opensymphony.xwork2.Action; import com.opensymphony.xwork2.ActionInvocation; import com.opensymphony.xwork2.ModelDriven; import com.opensymphony.xwork2.ValidationAware; import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor; import com.opensymphony.xwork2.util.logging.Logger; import com.opensymphony.xwork2.util.logging.LoggerFactory; import org.apache.commons.lang3.StringEscapeUtils; import org.apache.struts2.ServletActionContext; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.util.Collection; import java.util.List; import java.util.Map; /** * <p>Serializes validation and action errors into JSON. This interceptor does not * perform any validation, so it must follow the 'validation' interceptor on the stack. * </p> * * <p>This stack (defined in struts-default.xml) shows how to use this interceptor with the * 'validation' interceptor</p> * <pre> * <interceptor-stack name="jsonValidationWorkflowStack"> * <interceptor-ref name="basicStack"/> * <interceptor-ref name="validation"> * <param name="excludeMethods">input,back,cancel</param> * </interceptor-ref> * <interceptor-ref name="jsonValidation"/> * <interceptor-ref name="workflow"/> * </interceptor-stack> * </pre> * <p>If 'validationFailedStatus' is set it will be used as the Response status * when validation fails.</p> * * <p>If the request has a parameter 'struts.validateOnly' execution will return after * validation (action won't be executed).</p> * * <p>A request parameter named 'struts.enableJSONValidation' must be set to 'true' to * use this interceptor</p> * * <p>If the request has a parameter 'struts.JSONValidation.set.encoding' set to true * the character encoding will NOT be set on the response - is needed in portlet environment * - for more details see issue WW-3237</p> */ public class JSONValidationInterceptor extends MethodFilterInterceptor { private static final Logger LOG = LoggerFactory.getLogger(JSONValidationInterceptor.class); private static final String VALIDATE_ONLY_PARAM = "struts.validateOnly"; private static final String VALIDATE_JSON_PARAM = "struts.enableJSONValidation"; private static final String NO_ENCODING_SET_PARAM = "struts.JSONValidation.no.encoding"; private static final String DEFAULT_ENCODING = "UTF-8"; private int validationFailedStatus = -1; /** * HTTP status that will be set in the response if validation fails * @param validationFailedStatus */ public void setValidationFailedStatus(int validationFailedStatus) { this.validationFailedStatus = validationFailedStatus; } @Override protected String doIntercept(ActionInvocation invocation) throws Exception { HttpServletResponse response = ServletActionContext.getResponse(); HttpServletRequest request = ServletActionContext.getRequest(); Object action = invocation.getAction(); if (isJsonEnabled(request)) { if (action instanceof ValidationAware) { // generate json ValidationAware validationAware = (ValidationAware) action; if (validationAware.hasErrors()) { return generateJSON(request, response, validationAware); } } if (isValidateOnly(request)) { //there were no errors setupEncoding(response, request); response.getWriter().print("{}"); response.setContentType("application/json"); return Action.NONE; } else { return invocation.invoke(); } } else return invocation.invoke(); } private void setupEncoding(HttpServletResponse response, HttpServletRequest request) { if (isSetEncoding(request)) { if (LOG.isDebugEnabled()) { LOG.debug("Default encoding not set!"); } } else { if (LOG.isDebugEnabled()) { LOG.debug("Setting up encoding to: [" + DEFAULT_ENCODING + "]!"); } response.setCharacterEncoding(DEFAULT_ENCODING); } } private String generateJSON(HttpServletRequest request, HttpServletResponse response, ValidationAware validationAware) throws IOException { if (validationFailedStatus >= 0) { response.setStatus(validationFailedStatus); } setupEncoding(response, request); response.getWriter().print(buildResponse(validationAware)); response.setContentType("application/json"); return Action.NONE; } private boolean isJsonEnabled(HttpServletRequest request) { return "true".equals(request.getParameter(VALIDATE_JSON_PARAM)); } private boolean isValidateOnly(HttpServletRequest request) { return "true".equals(request.getParameter(VALIDATE_ONLY_PARAM)); } private boolean isSetEncoding(HttpServletRequest request) { return "true".equals(request.getParameter(NO_ENCODING_SET_PARAM)); } /** * @return JSON string that contains the errors and field errors */ @SuppressWarnings("unchecked") protected String buildResponse(ValidationAware validationAware) { //should we use FreeMarker here? StringBuilder sb = new StringBuilder(); sb.append("{ "); if (validationAware.hasErrors()) { //action errors if (validationAware.hasActionErrors()) { sb.append("\"errors\":"); sb.append(buildArray(validationAware.getActionErrors())); } //field errors if (validationAware.hasFieldErrors()) { if (validationAware.hasActionErrors()) sb.append(","); sb.append("\"fieldErrors\": {"); Map<String, List<String>> fieldErrors = validationAware.getFieldErrors(); for (Map.Entry<String, List<String>> fieldError : fieldErrors.entrySet()) { sb.append("\""); //if it is model driven, remove "model." see WW-2721 String fieldErrorKey = fieldError.getKey(); sb.append(((validationAware instanceof ModelDriven) && fieldErrorKey.startsWith("model.")) ? fieldErrorKey.substring(6) : fieldErrorKey); sb.append("\":"); sb.append(buildArray(fieldError.getValue())); sb.append(","); } //remove trailing comma, IE creates an empty object, duh sb.deleteCharAt(sb.length() - 1); sb.append("}"); } } sb.append("}"); /*response should be something like: * { * "errors": ["this", "that"], * "fieldErrors": { * field1: "this", * field2: "that" * } * } */ return sb.toString(); } private String buildArray(Collection<String> values) { StringBuilder sb = new StringBuilder(); sb.append("["); for (String value : values) { sb.append("\""); sb.append(StringEscapeUtils.escapeJson(value)); sb.append("\","); } if (values.size() > 0) sb.deleteCharAt(sb.length() - 1); sb.append("]"); return sb.toString(); } }