org.springframework.web.util.ContentCachingResponseWrapper Maven / Gradle / Ivy
/*
* Copyright 2002-2022 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.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import jakarta.servlet.ServletOutputStream;
import jakarta.servlet.WriteListener;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpServletResponseWrapper;
import org.springframework.http.HttpHeaders;
import org.springframework.lang.Nullable;
import org.springframework.util.FastByteArrayOutputStream;
/**
* {@link jakarta.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}.
*
* Used e.g. by {@link org.springframework.web.filter.ShallowEtagHeaderFilter}.
*
* @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.
* @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
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);
}
}
@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 has not been copied to it yet
}
@Override
public void setContentLength(int len) {
if (len > this.content.size()) {
this.content.resize(len);
}
this.contentLength = len;
}
@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 cached response content as a byte array.
*/
public byte[] getContentAsByteArray() {
return this.content.toByteArray();
}
/**
* 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
*/
public int getContentSize() {
return this.content.size();
}
/**
* 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.
* @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();
}
}
}