* Wrapper:在内存中开辟一个ByteOutputStream，然后将拦截的响应写入byte[]，
* 写入完毕后，再将wrapper的byte[]写入真正的response对象
* This class is used for wrapped response for getting cached data.
*/
class CachedResponseWrapper extends HttpServletResponseWrapper {
/**
* Indicate that getOutputStream() or getWriter() is not called yet.
*/
public static final int OUTPUT_NONE = 0;
/**
* Indicate that getWriter() is already called.
*/
public static final int OUTPUT_WRITER = 1;
/**
* Indicate that getOutputStream() is already called.
*/
public static final int OUTPUT_STREAM = 2;
private int outputType = OUTPUT_NONE;
private int status = SC_OK;
private ServletOutputStream output = null;
private PrintWriter writer = null;
private ByteArrayOutputStream buffer = null;
public CachedResponseWrapper(HttpServletResponse resp) throws
IOException {
super(resp);
buffer = new ByteArrayOutputStream();
}
public int getStatus() {
return status;
}
public void setStatus(int status) {
this.status = status;
}
public void setStatus(int status, String string) {
super.setStatus(status, string);
this.status = status;
}
public void sendError(int status, String string) throws IOException
{
super.sendError(status, string);
this.status = status;
}
public void sendError(int status) throws IOException {
super.sendError(status);
this.status = status;
}
public void sendRedirect(String location) throws IOException {
super.sendRedirect(location);
this.status = SC_MOVED_TEMPORARILY;
}
public PrintWriter getWriter() throws IOException {
if (outputType == OUTPUT_STREAM)
throw new IllegalStateException();
else if (outputType == OUTPUT_WRITER)
return writer;
else {
outputType = OUTPUT_WRITER;
writer = new PrintWriter(new OutputStreamWriter(buffer,
getCharacterEncoding()));
return writer;
}
}
public ServletOutputStream getOutputStream() throws IOException {
if (outputType == OUTPUT_WRITER)
throw new IllegalStateException();
else if (outputType == OUTPUT_STREAM)
return output;
else {