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SPR-5825 - ShallowEtagHeaderFilter doesn't work: response body is empty

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This commit is contained in:
Arjen Poutsma
2009-06-15 10:58:45 +00:00
parent c254924b4c
commit 444378c426
2 changed files with 78 additions and 19 deletions
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69
org.springframework.web/src/main/java/org/springframework/web/filter/ShallowEtagHeaderFilter.java
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@@ -20,7 +20,7 @@ import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Writer;
import java.io.UnsupportedEncodingException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
@@ -32,12 +32,12 @@ import org.springframework.util.FileCopyUtils;
import org.springframework.util.Md5HashUtils;
/**
* {@link javax.servlet.Filter} that generates an <code>ETag</code> value based on the content
* on the response. This ETag is compared to the <code>If-None-Match</code> header of the request.
* If these headers are equal, the resonse content is not sent, but rather a 304 "Not Modified" status.
* {@link javax.servlet.Filter} that generates an <code>ETag</code> value based on the content on the response. This
* ETag is compared to the <code>If-None-Match</code> header of the request. If these headers are equal, the resonse
* content is not sent, but rather a 304 "Not Modified" status.
*
* <p>Since the ETag is based on the response content, the response (or {@link org.springframework.web.servlet.View})
* is still rendered. As such, this filter only saves bandwidth, not server performance.
* <p>Since the ETag is based on the response content, the response (or {@link org.springframework.web.servlet.View}) is
* still rendered. As such, this filter only saves bandwidth, not server performance.
*
* @author Arjen Poutsma
* @since 3.0
@@ -48,7 +48,6 @@ public class ShallowEtagHeaderFilter extends OncePerRequestFilter {
private static String HEADER_IF_NONE_MATCH = "If-None-Match";
@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
@@ -78,8 +77,9 @@ public class ShallowEtagHeaderFilter extends OncePerRequestFilter {
}
/**
* Generate the ETag header value from the given response body byte array.
* <p>The default implementation generates an MD5 hash.
* Generate the ETag header value from the given response body byte array. <p>The default implementation generates an
* MD5 hash.
*
* @param bytes the response bdoy as byte array
* @return the ETag header value
* @see Md5HashUtils
@@ -91,11 +91,10 @@ public class ShallowEtagHeaderFilter extends OncePerRequestFilter {
return builder.toString();
}
/**
* {@link HttpServletRequest} wrapper that buffers all content written to the
* {@linkplain #getOutputStream() output stream} and {@linkplain #getWriter() writer},
* and allows this content to be retrieved via a {@link #toByteArray() byte array}.
* {@link HttpServletRequest} wrapper that buffers all content written to the {@linkplain #getOutputStream() output
* stream} and {@linkplain #getWriter() writer}, and allows this content to be retrieved via a {@link #toByteArray()
* byte array}.
*/
private static class ShallowEtagResponseWrapper extends HttpServletResponseWrapper {
@@ -118,10 +117,8 @@ public class ShallowEtagHeaderFilter extends OncePerRequestFilter {
public PrintWriter getWriter() throws IOException {
if (this.writer == null) {
String characterEncoding = getCharacterEncoding();
Writer targetWriter = (characterEncoding != null ?
new OutputStreamWriter(this.outputStream, characterEncoding) :
new OutputStreamWriter(this.outputStream));
this.writer = new PrintWriter(targetWriter);
this.writer = (characterEncoding != null ? new ResponsePrintWriter(characterEncoding) :
new ResponsePrintWriter());
}
return this.writer;
}
@@ -141,14 +138,50 @@ public class ShallowEtagHeaderFilter extends OncePerRequestFilter {
return this.content.toByteArray();
}
private class ResponseServletOutputStream extends ServletOutputStream {
@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);
}
}
private class ResponsePrintWriter extends PrintWriter {
private ResponsePrintWriter() {
super(new OutputStreamWriter(content));
}
private 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();
}
}
}
}