org.springframework.web.servlet.mvc.method.annotation.AbstractJsonpResponseBodyAdvice.java Source code

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/*
 * Copyright 2002-2015 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
 *
 * 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.web.servlet.mvc.method.annotation;

import java.util.regex.Pattern;
import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.core.MethodParameter;
import org.springframework.http.MediaType;
import org.springframework.http.converter.json.MappingJacksonValue;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.http.server.ServletServerHttpRequest;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;

/**
 * A convenient base class for a {@code ResponseBodyAdvice} to instruct the
 * {@link org.springframework.http.converter.json.MappingJackson2HttpMessageConverter}
 * to serialize with JSONP formatting.
 *
 * <p>Sub-classes must specify the query parameter name(s) to check for the name
 * of the JSONP callback function.
 *
 * <p>Sub-classes are likely to be annotated with the {@code @ControllerAdvice}
 * annotation and auto-detected or otherwise must be registered directly with the
 * {@code RequestMappingHandlerAdapter} and {@code ExceptionHandlerExceptionResolver}.
 *
 * @author Rossen Stoyanchev
 * @since 4.1
 */
public abstract class AbstractJsonpResponseBodyAdvice extends AbstractMappingJacksonResponseBodyAdvice {

    /**
     * Pattern for validating jsonp callback parameter values.
     */
    private static final Pattern CALLBACK_PARAM_PATTERN = Pattern.compile("[0-9A-Za-z_\\.]*");

    private final Log logger = LogFactory.getLog(getClass());

    private final String[] jsonpQueryParamNames;

    protected AbstractJsonpResponseBodyAdvice(String... queryParamNames) {
        Assert.isTrue(!ObjectUtils.isEmpty(queryParamNames), "At least one query param name is required");
        this.jsonpQueryParamNames = queryParamNames;
    }

    @Override
    protected void beforeBodyWriteInternal(MappingJacksonValue bodyContainer, MediaType contentType,
            MethodParameter returnType, ServerHttpRequest request, ServerHttpResponse response) {

        HttpServletRequest servletRequest = ((ServletServerHttpRequest) request).getServletRequest();

        for (String name : this.jsonpQueryParamNames) {
            String value = servletRequest.getParameter(name);
            if (value != null) {
                if (!isValidJsonpQueryParam(value)) {
                    if (logger.isDebugEnabled()) {
                        logger.debug("Ignoring invalid jsonp parameter value: " + value);
                    }
                    continue;
                }
                MediaType contentTypeToUse = getContentType(contentType, request, response);
                response.getHeaders().setContentType(contentTypeToUse);
                bodyContainer.setJsonpFunction(value);
                break;
            }
        }
    }

    /**
     * Validate the jsonp query parameter value. The default implementation
     * returns true if it consists of digits, letters, or "_" and ".".
     * Invalid parameter values are ignored.
     * @param value the query param value, never {@code null}
     * @since 4.1.8
     */
    protected boolean isValidJsonpQueryParam(String value) {
        return CALLBACK_PARAM_PATTERN.matcher(value).matches();
    }

    /**
     * Return the content type to set the response to.
     * This implementation always returns "application/javascript".
     * @param contentType the content type selected through content negotiation
     * @param request the current request
     * @param response the current response
     * @return the content type to set the response to
     */
    protected MediaType getContentType(MediaType contentType, ServerHttpRequest request,
            ServerHttpResponse response) {
        return new MediaType("application", "javascript");
    }

}