/*
 * 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.
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package org.springframework.web.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;

import javax.servlet.ServletOutputStream;
import javax.servlet.WriteListener;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

import org.springframework.http.HttpHeaders;
import org.springframework.lang.Nullable;
import org.springframework.util.FastByteArrayOutputStream;

HttpServletResponse wrapper that caches all content written to the output stream and writer, and allows this content to be retrieved via a byte array.

Used e.g. by ShallowEtagHeaderFilter. Note: As of Spring Framework 5.0, this wrapper is built on the Servlet 3.1 API.

Author:Juergen Hoeller
See Also:
Since:4.1.3
/** * {@link javax.servlet.http.HttpServletResponse} wrapper that caches all content written to * the {@linkplain #getOutputStream() output stream} and {@linkplain #getWriter() writer}, * and allows this content to be retrieved via a {@link #getContentAsByteArray() byte array}. * * <p>Used e.g. by {@link org.springframework.web.filter.ShallowEtagHeaderFilter}. * Note: As of Spring Framework 5.0, this wrapper is built on the Servlet 3.1 API. * * @author Juergen Hoeller * @since 4.1.3 * @see ContentCachingRequestWrapper */
public class ContentCachingResponseWrapper extends HttpServletResponseWrapper { private final FastByteArrayOutputStream content = new FastByteArrayOutputStream(1024); @Nullable private ServletOutputStream outputStream; @Nullable private PrintWriter writer; @Nullable private Integer contentLength;
Create a new ContentCachingResponseWrapper for the given servlet response.
Params:
  • response – the original servlet response
/** * Create a new ContentCachingResponseWrapper for the given servlet response. * @param response the original servlet response */
public ContentCachingResponseWrapper(HttpServletResponse response) { super(response); } @Override public void sendError(int sc) throws IOException { copyBodyToResponse(false); try { super.sendError(sc); } catch (IllegalStateException ex) { // Possibly on Tomcat when called too late: fall back to silent setStatus super.setStatus(sc); } } @Override @SuppressWarnings("deprecation") public void sendError(int sc, String msg) throws IOException { copyBodyToResponse(false); try { super.sendError(sc, msg); } catch (IllegalStateException ex) { // Possibly on Tomcat when called too late: fall back to silent setStatus super.setStatus(sc, msg); } } @Override public void sendRedirect(String location) throws IOException { copyBodyToResponse(false); super.sendRedirect(location); } @Override public ServletOutputStream getOutputStream() throws IOException { if (this.outputStream == null) { this.outputStream = new ResponseServletOutputStream(getResponse().getOutputStream()); } return this.outputStream; } @Override public PrintWriter getWriter() throws IOException { if (this.writer == null) { String characterEncoding = getCharacterEncoding(); this.writer = (characterEncoding != null ? new ResponsePrintWriter(characterEncoding) : new ResponsePrintWriter(WebUtils.DEFAULT_CHARACTER_ENCODING)); } return this.writer; } @Override public void flushBuffer() throws IOException { // do not flush the underlying response as the content as not been copied to it yet } @Override public void setContentLength(int len) { if (len > this.content.size()) { this.content.resize(len); } this.contentLength = len; } // Overrides Servlet 3.1 setContentLengthLong(long) at runtime @Override public void setContentLengthLong(long len) { if (len > Integer.MAX_VALUE) { throw new IllegalArgumentException("Content-Length exceeds ContentCachingResponseWrapper's maximum (" + Integer.MAX_VALUE + "): " + len); } int lenInt = (int) len; if (lenInt > this.content.size()) { this.content.resize(lenInt); } this.contentLength = lenInt; } @Override public void setBufferSize(int size) { if (size > this.content.size()) { this.content.resize(size); } } @Override public void resetBuffer() { this.content.reset(); } @Override public void reset() { super.reset(); this.content.reset(); }
Return the status code as specified on the response.
Deprecated:as of 5.2 in favor of getStatus.getStatus()
/** * Return the status code as specified on the response. * @deprecated as of 5.2 in favor of {@link HttpServletResponse#getStatus()} */
@Deprecated public int getStatusCode() { return getStatus(); }
Return the cached response content as a byte array.
/** * Return the cached response content as a byte array. */
public byte[] getContentAsByteArray() { return this.content.toByteArray(); }
Return an InputStream to the cached content.
Since:4.2
/** * Return an {@link InputStream} to the cached content. * @since 4.2 */
public InputStream getContentInputStream() { return this.content.getInputStream(); }
Return the current size of the cached content.
Since:4.2
/** * Return the current size of the cached content. * @since 4.2 */
public int getContentSize() { return this.content.size(); }
Copy the complete cached body content to the response.
Since:4.2
/** * Copy the complete cached body content to the response. * @since 4.2 */
public void copyBodyToResponse() throws IOException { copyBodyToResponse(true); }
Copy the cached body content to the response.
Params:
  • complete – whether to set a corresponding content length for the complete cached body content
Since:4.2
/** * Copy the cached body content to the response. * @param complete whether to set a corresponding content length * for the complete cached body content * @since 4.2 */
protected void copyBodyToResponse(boolean complete) throws IOException { if (this.content.size() > 0) { HttpServletResponse rawResponse = (HttpServletResponse) getResponse(); if ((complete || this.contentLength != null) && !rawResponse.isCommitted()) { if (rawResponse.getHeader(HttpHeaders.TRANSFER_ENCODING) == null) { rawResponse.setContentLength(complete ? this.content.size() : this.contentLength); } this.contentLength = null; } this.content.writeTo(rawResponse.getOutputStream()); this.content.reset(); if (complete) { super.flushBuffer(); } } } private class ResponseServletOutputStream extends ServletOutputStream { private final ServletOutputStream os; public ResponseServletOutputStream(ServletOutputStream os) { this.os = os; } @Override public void write(int b) throws IOException { content.write(b); } @Override public void write(byte[] b, int off, int len) throws IOException { content.write(b, off, len); } @Override public boolean isReady() { return this.os.isReady(); } @Override public void setWriteListener(WriteListener writeListener) { this.os.setWriteListener(writeListener); } } private class ResponsePrintWriter extends PrintWriter { public ResponsePrintWriter(String characterEncoding) throws UnsupportedEncodingException { super(new OutputStreamWriter(content, characterEncoding)); } @Override public void write(char[] buf, int off, int len) { super.write(buf, off, len); super.flush(); } @Override public void write(String s, int off, int len) { super.write(s, off, len); super.flush(); } @Override public void write(int c) { super.write(c); super.flush(); } } }