ErrorWrapperResponse Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/web/servlet/support/ErrorPageFilter.java lines 311–378

	private static class ErrorWrapperResponse extends HttpServletResponseWrapper {

		private int status;

		private @Nullable String message;

		private boolean hasErrorToSend;

		ErrorWrapperResponse(HttpServletResponse response) {
			super(response);
		}

		@Override
		public void sendError(int status) {
			sendError(status, null);
		}

		@Override
		public void sendError(int status, @Nullable String message) {
			this.status = status;
			this.message = message;
			this.hasErrorToSend = true;
			// Do not call super because the container may prevent us from handling the
			// error ourselves
		}

		@Override
		public int getStatus() {
			if (this.hasErrorToSend) {
				return this.status;
			}
			// If there was no error we need to trust the wrapped response
			return super.getStatus();
		}

		@Override
		public void flushBuffer() throws IOException {
			sendErrorIfNecessary();
			super.flushBuffer();
		}

		private void sendErrorIfNecessary() throws IOException {
			if (this.hasErrorToSend && !isCommitted()) {
				((HttpServletResponse) getResponse()).sendError(this.status, this.message);
			}
		}

		@Nullable String getMessage() {
			return this.message;
		}

		boolean hasErrorToSend() {
			return this.hasErrorToSend;
		}

		@Override
		public PrintWriter getWriter() throws IOException {
			sendErrorIfNecessary();
			return super.getWriter();
		}

		@Override
		public ServletOutputStream getOutputStream() throws IOException {
			sendErrorIfNecessary();
			return super.getOutputStream();
		}

	}