Avoid loss of body content in AbstractRequestLoggingFilter

Prior to this commit, the `ContentCachingRequestWrapper` class would
cache the response content only if the reponse would be consumed using
its InputStream. In case of a Form request, Spring MVC consumes the
response using the `getParameter*` Servlet API methods. This causes the
cached content to never be written.

This commit makes the `ContentCachingResponseWrapper` write the request
body to the cache buffer by using the `getParameter*` API, thus avoiding
those issues.

Issue: SPR-7913

Author: bclozel

spring-web/src/main/java/org/springframework/web/util/ContentCachingRequestWrapper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * 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.
@@ -20,6 +20,14 @@
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.io.UnsupportedEncodingException;
+import java.net.URLEncoder;
+import java.util.Arrays;
+import java.util.Enumeration;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+
 import javax.servlet.ServletInputStream;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletRequestWrapper;
@@ -36,6 +44,10 @@
  */
 public class ContentCachingRequestWrapper extends HttpServletRequestWrapper {
 
+	private static final String FORM_CONTENT_TYPE = "application/x-www-form-urlencoded";
+
+	private static final String METHOD_POST = "POST";
+
 	private final ByteArrayOutputStream cachedContent;
 
 	private ServletInputStream inputStream;
@@ -80,9 +92,46 @@ public BufferedReader getReader() throws IOException {
 	 * Return the cached request content as a byte array.
 	 */
 	public byte[] getContentAsByteArray() {
+		if(this.cachedContent.size() == 0 && isFormPost()) {
+			writeRequestParamsToContent();
+		}
 		return this.cachedContent.toByteArray();
 	}
 
+	private boolean isFormPost() {
+		return (getContentType() != null && getContentType().contains(FORM_CONTENT_TYPE) &&
+				METHOD_POST.equalsIgnoreCase(getMethod()));
+	}
+
+	private void writeRequestParamsToContent() {
+		try {
+			if (this.cachedContent.size() == 0) {
+				String requestEncoding = getCharacterEncoding();
+				Map<String, String[]> form = getParameterMap();
+				for (Iterator<String> nameIterator = form.keySet().iterator(); nameIterator.hasNext(); ) {
+					String name = nameIterator.next();
+					List<String> values = Arrays.asList(form.get(name));
+					for (Iterator<String> valueIterator = values.iterator(); valueIterator.hasNext(); ) {
+						String value = valueIterator.next();
+						cachedContent.write(URLEncoder.encode(name, requestEncoding).getBytes());
+						if (value != null) {
+							cachedContent.write('=');
+							cachedContent.write(URLEncoder.encode(value, requestEncoding).getBytes());
+							if (valueIterator.hasNext()) {
+								cachedContent.write('&');
+							}
+						}
+					}
+					if (nameIterator.hasNext()) {
+						cachedContent.write('&');
+					}
+				}
+			}
+		}
+		catch (IOException e) {
+			throw new RuntimeException(e);
+		}
+	}
 
 	private class ContentCachingInputStream extends ServletInputStream {
 

spring-web/src/test/java/org/springframework/web/util/ContentCachingRequestWrapperTests.java

@@ -0,0 +1,66 @@
+/*
+ * 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.util;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import org.springframework.mock.web.test.MockHttpServletRequest;
+import org.springframework.util.FileCopyUtils;
+
+/**
+ * @author Brian Clozel
+ */
+public class ContentCachingRequestWrapperTests {
+
+	protected static final String FORM_CONTENT_TYPE = "application/x-www-form-urlencoded";
+
+	protected static final String CHARSET = "UTF-8";
+
+	private MockHttpServletRequest request;
+
+	@Before
+	public void setup() throws Exception {
+		this.request = new MockHttpServletRequest();
+	}
+
+	@Test
+	public void cachedContent() throws Exception {
+		this.request.setMethod("GET");
+		this.request.setCharacterEncoding(CHARSET);
+		this.request.setContent("Hello World".getBytes(CHARSET));
+
+		ContentCachingRequestWrapper wrapper = new ContentCachingRequestWrapper(this.request);
+		byte[] response = FileCopyUtils.copyToByteArray(wrapper.getInputStream());
+		Assert.assertArrayEquals(response, wrapper.getContentAsByteArray());
+	}
+
+	@Test
+	public void requestParams() throws Exception {
+		this.request.setMethod("POST");
+		this.request.setContentType(FORM_CONTENT_TYPE);
+		this.request.setCharacterEncoding(CHARSET);
+		this.request.setParameter("first", "value");
+		this.request.setParameter("second", new String[] {"foo", "bar"});
+
+		ContentCachingRequestWrapper wrapper = new ContentCachingRequestWrapper(this.request);
+		// getting request parameters will consume the request body
+		Assert.assertFalse(wrapper.getParameterMap().isEmpty());
+		Assert.assertEquals("first=value&second=foo&second=bar", new String(wrapper.getContentAsByteArray()));
+	}
+
+}