解决HttpServletRequest#getIntputStream只能读一次
- 2019 年 12 月 19 日
- 笔记
解决HttpServletRequest#getIntputStream只能读一次
以前一直自己封装一个Wrapper来缓存Body的内容，今天发现在Spring中已经帮我们实现了。就是org.springframework.web.util.ContentCachingRequestWrapper
贴上源码
/* * Copyright 2002-2018 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.web.util; import java.io.BufferedReader; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStreamReader; 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.ReadListener; import javax.servlet.ServletInputStream; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletRequestWrapper; import org.springframework.http.HttpMethod; import org.springframework.lang.Nullable; /** * {@link javax.servlet.http.HttpServletRequest} wrapper that caches all content read from * the {@linkplain #getInputStream() input stream} and {@linkplain #getReader() reader}, * and allows this content to be retrieved via a {@link #getContentAsByteArray() byte array}. * * <p>Used e.g. by {@link org.springframework.web.filter.AbstractRequestLoggingFilter}. * Note: As of Spring Framework 5.0, this wrapper is built on the Servlet 3.1 API. * * @author Juergen Hoeller * @author Brian Clozel * @since 4.1.3 * @see ContentCachingResponseWrapper */ public class ContentCachingRequestWrapper extends HttpServletRequestWrapper { private static final String FORM_CONTENT_TYPE = "application/x-www-form-urlencoded"; private final ByteArrayOutputStream cachedContent; @Nullable private final Integer contentCacheLimit; @Nullable private ServletInputStream inputStream; @Nullable private BufferedReader reader; /** * Create a new ContentCachingRequestWrapper for the given servlet request. * @param request the original servlet request */ public ContentCachingRequestWrapper(HttpServletRequest request) { super(request); int contentLength = request.getContentLength(); this.cachedContent = new ByteArrayOutputStream(contentLength >= 0 ? contentLength : 1024); this.contentCacheLimit = null; } /** * Create a new ContentCachingRequestWrapper for the given servlet request. * @param request the original servlet request * @param contentCacheLimit the maximum number of bytes to cache per request * @since 4.3.6 * @see #handleContentOverflow(int) */ public ContentCachingRequestWrapper(HttpServletRequest request, int contentCacheLimit) { super(request); this.cachedContent = new ByteArrayOutputStream(contentCacheLimit); this.contentCacheLimit = contentCacheLimit; } @Override public ServletInputStream getInputStream() throws IOException { if (this.inputStream == null) { this.inputStream = new ContentCachingInputStream(getRequest().getInputStream()); } return this.inputStream; } @Override public String getCharacterEncoding() { String enc = super.getCharacterEncoding(); return (enc != null ? enc : WebUtils.DEFAULT_CHARACTER_ENCODING); } @Override public BufferedReader getReader() throws IOException { if (this.reader == null) { this.reader = new BufferedReader(new InputStreamReader(getInputStream(), getCharacterEncoding())); } return this.reader; } @Override public String getParameter(String name) { if (this.cachedContent.size() == 0 && isFormPost()) { writeRequestParametersToCachedContent(); } return super.getParameter(name); } @Override public Map<String, String[]> getParameterMap() { if (this.cachedContent.size() == 0 && isFormPost()) { writeRequestParametersToCachedContent(); } return super.getParameterMap(); } @Override public Enumeration<String> getParameterNames() { if (this.cachedContent.size() == 0 && isFormPost()) { writeRequestParametersToCachedContent(); } return super.getParameterNames(); } @Override public String[] getParameterValues(String name) { if (this.cachedContent.size() == 0 && isFormPost()) { writeRequestParametersToCachedContent(); } return super.getParameterValues(name); } private boolean isFormPost() { String contentType = getContentType(); return (contentType != null && contentType.contains(FORM_CONTENT_TYPE) && HttpMethod.POST.matches(getMethod())); } private void writeRequestParametersToCachedContent() { try { if (this.cachedContent.size() == 0) { String requestEncoding = getCharacterEncoding(); Map<String, String[]> form = super.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(); this.cachedContent.write(URLEncoder.encode(name, requestEncoding).getBytes()); if (value != null) { this.cachedContent.write('='); this.cachedContent.write(URLEncoder.encode(value, requestEncoding).getBytes()); if (valueIterator.hasNext()) { this.cachedContent.write('&'); } } } if (nameIterator.hasNext()) { this.cachedContent.write('&'); } } } } catch (IOException ex) { throw new IllegalStateException("Failed to write request parameters to cached content", ex); } } /** * Return the cached request content as a byte array. * <p>The returned array will never be larger than the content cache limit. * @see #ContentCachingRequestWrapper(HttpServletRequest, int) */ public byte[] getContentAsByteArray() { return this.cachedContent.toByteArray(); } /** * Template method for handling a content overflow: specifically, a request * body being read that exceeds the specified content cache limit. * <p>The default implementation is empty. Subclasses may override this to * throw a payload-too-large exception or the like. * @param contentCacheLimit the maximum number of bytes to cache per request * which has just been exceeded * @since 4.3.6 * @see #ContentCachingRequestWrapper(HttpServletRequest, int) */ protected void handleContentOverflow(int contentCacheLimit) { } private class ContentCachingInputStream extends ServletInputStream { private final ServletInputStream is; private boolean overflow = false; public ContentCachingInputStream(ServletInputStream is) { this.is = is; } @Override public int read() throws IOException { int ch = this.is.read(); if (ch != -1 && !this.overflow) { if (contentCacheLimit != null && cachedContent.size() == contentCacheLimit) { this.overflow = true; handleContentOverflow(contentCacheLimit); } else { cachedContent.write(ch); } } return ch; } @Override public int read(byte[] b) throws IOException { int count = this.is.read(b); writeToCache(b, 0, count); return count; } private void writeToCache(final byte[] b, final int off, int count) { if (!this.overflow && count > 0) { if (contentCacheLimit != null && count + cachedContent.size() > contentCacheLimit) { this.overflow = true; cachedContent.write(b, off, contentCacheLimit - cachedContent.size()); handleContentOverflow(contentCacheLimit); return; } cachedContent.write(b, off, count); } } @Override public int read(final byte[] b, final int off, final int len) throws IOException { int count = this.is.read(b, off, len); writeToCache(b, off, count); return count; } @Override public int readLine(final byte[] b, final int off, final int len) throws IOException { int count = this.is.readLine(b, off, len); writeToCache(b, off, count); return count; } @Override public boolean isFinished() { return this.is.isFinished(); } @Override public boolean isReady() { return this.is.isReady(); } @Override public void setReadListener(ReadListener readListener) { this.is.setReadListener(readListener); } } }
Spring中还提供了一个filter来打印http请求的日志，org.springframework.web.filter.AbstractRequestLoggingFilter，其中就是引用了ContentCachingRequestWrapper
