完善ssrc符合国标，并完善很多小问题

src/main/java/com/genersoft/iot/vmp/vmanager/playback/PlaybackController.java

@@ -0,0 +1,47 @@
+package com.genersoft.iot.vmp.vmanager.playback;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.genersoft.iot.vmp.gb28181.bean.Device;
+import com.genersoft.iot.vmp.gb28181.transmit.cmd.impl.SIPCommander;
+import com.genersoft.iot.vmp.storager.IVideoManagerStorager;
+
+@RestController
+@RequestMapping("/api")
+public class PlaybackController {
+	
+	private final static Logger logger = LoggerFactory.getLogger(PlaybackController.class);
+	
+	@Autowired
+	private SIPCommander cmder;
+	
+	@Autowired
+	private IVideoManagerStorager storager;
+	
+	@GetMapping("/playback/{deviceId}/{channelId}")
+	public ResponseEntity<String> play(@PathVariable String deviceId,@PathVariable String channelId, String startTime,  String endTime){
+		
+		Device device = storager.queryVideoDevice(deviceId);
+		String ssrc = cmder.playStreamCmd(device, channelId);
+		
+		if (logger.isDebugEnabled()) {
+			logger.debug(String.format("设备预览 API调用，deviceId：%s ，channelId：%s",deviceId, channelId));
+			logger.debug("设备预览 API调用，ssrc："+ssrc+",ZLMedia streamId:"+Integer.toHexString(Integer.parseInt(ssrc)));
+		}
+		
+		if(ssrc!=null) {
+			return new ResponseEntity<String>(ssrc,HttpStatus.OK);
+		} else {
+			logger.warn("设备预览API调用失败！");
+			return new ResponseEntity<String>(HttpStatus.INTERNAL_SERVER_ERROR);
+		}
+	}
+}