/**
* Copyright 2010-2014 Ralph Schaer <ralphschaer@gmail.com>
*
* 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
*
* http://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 ch.ralscha.extdirectspring.controller;
import java.io.IOException;
import javax.servlet.http.HttpServletResponse;
import org.springframework.http.MediaType;
import org.springframework.util.StringUtils;
import ch.ralscha.extdirectspring.bean.SSEvent;
import ch.ralscha.extdirectspring.util.ExtDirectSpringUtil;
/**
* This class allows you to send server sent events in a streaming fashion. Add
* this class as a parameter to the method and send {@link SSEvent} with
* {@link #write(SSEvent)} to the client.
* <p>
* Example:
*
* <pre>
* {@literal @}ExtDirectMethod(ExtDirectMethodType.SSE)
* public void sse(SSEWriter sseWriter) {
* SSEvent event = new SSEvent();
* event.set....
* sseWriter.write(event);
* //do something else or wait for something or ...
* sseWriter.write(event);
* //...
* }
* </pre>
*/
public class SSEWriter {
private final HttpServletResponse response;
private static final MediaType EVENT_STREAM = new MediaType("text", "event-stream",
ExtDirectSpringUtil.UTF8_CHARSET);
public SSEWriter(HttpServletResponse response) {
this.response = response;
response.setContentType(EVENT_STREAM.toString());
response.setCharacterEncoding(EVENT_STREAM.getCharSet().name());
}
/**
* Creates a {@link SSEvent} object and sets the data property to the
* provided parameter. Then it writes the event into the servlet output
* stream and flushes the response.
*
* @param data the value that becomes the data part of the {@link SSEvent}.
* If null nothing is written.
* @throws IOException
*/
public void write(Object data) throws IOException {
if (data != null) {
SSEvent sseEvent = new SSEvent();
sseEvent.setData(data.toString());
write(sseEvent);
}
}
/**
* Writes the event into the servlet output stream and flushes the response.
* The method does not close the output stream.
*
* @param sseEvent the event object
* @throws IOException
*/
public void write(SSEvent sseEvent) throws IOException {
StringBuilder sb = new StringBuilder(32);
if (StringUtils.hasText(sseEvent.getComment())) {
for (String line : sseEvent.getComment().split("\\r?\\n|\\r")) {
sb.append(":").append(line).append("\n");
}
}
if (StringUtils.hasText(sseEvent.getId())) {
sb.append("id:").append(sseEvent.getId()).append("\n");
}
if (StringUtils.hasText(sseEvent.getEvent())) {
sb.append("event:").append(sseEvent.getEvent()).append("\n");
}
if (StringUtils.hasText(sseEvent.getData())) {
for (String line : sseEvent.getData().split("\\r?\\n|\\r")) {
sb.append("data:").append(line).append("\n");
}
}
if (sseEvent.getRetry() != null) {
sb.append("retry:").append(sseEvent.getRetry()).append("\n");
}
sb.append("\n");
response.getOutputStream().write(sb.toString().getBytes(ExtDirectSpringUtil.UTF8_CHARSET));
response.getOutputStream().flush();
}
}