仿牛客社区——7.19生成长图

 采用异步方式，通过任务方式，将次命令丢到消息队列中进行执行

关于wkhtmltopdf的配置（applaction.properties）

#关于wk的配置（生成长图

wk.image.command=D:/wkhtmltopdf/bin/wkhtmltoimage

wk.image.storage=D:/wkData/wk-images

生成主题常量

//主题：分享

String TOPIC_SHARE="share";

 wkconfig

在项目第一次启动的时候生成储存对应长图的目录

@Configuration
public class WkConfig {
	//在服务启动时生成图片目录
	private final static Logger logger= LoggerFactory.getLogger(WkConfig.class);

	@Value("${wk.image.storage}")
	private String wkImageStorage;
	@PostConstruct
	public void init(){

		//创建wk图片目录
		File file=new File(wkImageStorage);
		if(!file.exists()){
			file.mkdir();
			logger.info("创建wk图片目录："+wkImageStorage);
		}
	}
}

controller

@Controller
public class ShareController implements CommunityConstant {

	private static final Logger logger = LoggerFactory.getLogger(ShareController.class);


	@Autowired
	private EventProducer eventProducer;

	//域名
	@Value("${community.path.domain}")
	private String domain;

	//项目名
	@Value("${server.servlet.context-path}")
	private String contextPath;

	//存储路径
	@Value("${wk.image.storage}")
	private String wkImageStorage;

	@RequestMapping(value = "/share", method = RequestMethod.GET)
	@ResponseBody
	public String shareImage(String htmlUrl) {

		String fileName = CommunityUtil.generateUUID();  //文件名

		Event event = new Event()
				.setTopic(TOPIC_SHARE)
				.setData("htmlUrl", htmlUrl)  //请求路径
				.setData("fileName", fileName) //文件名
				.setData("suffix", ".png"); //文件后缀

		//异步方式：通过事件发送
		eventProducer.fireEvent(event);

		//返回访问路径
		Map<String, Object> map = new HashMap<>();
		map.put("shareUrl", domain + contextPath + "/share/image/" + fileName);
		// eg: http://localhost:8080/community/share/image/33365834673863

		return CommunityUtil.getJsonString(0, null, map);
	}

	//获取长图(直接给浏览器返回一个图片，需要用response处理
	@RequestMapping(value = "/share/image/{fileName}", method = RequestMethod.GET)
	public void getImage(@PathVariable(name = "fileName") String fileName, HttpServletResponse response) {
		if (StringUtils.isBlank(fileName)) {
			throw new IllegalArgumentException("文件名不能为空！");
		}

		response.setContentType("image/png");

		//从本地读取文件
		File file = new File(wkImageStorage + "/" + fileName + ".png");

		try {
			OutputStream os = response.getOutputStream();
			FileInputStream is=new FileInputStream(file); //文件流：读取文件
			byte[] buffer=new byte[1024];
			int len=0;
			while((len=is.read(buffer))!=-1){
				os.write(buffer,0,len);
			}
		} catch (IOException e) {
			logger.error("获取长图失败："+e.getMessage());
		}


	}
}

consumer

	//存储路径
	@Value("${wk.image.storage}")
	private String wkImageStorage;

	@Value("${wk.image.command}")
	private String wkImageCommand;

@KafkaListener(topics = TOPIC_SHARE)
	public void handleShare(ConsumerRecord record){
		//先进行判断record是否为空:未发事件或者发送的事件为空
		if(record==null|| record.value()==null){
			logger.error("发送的消息为空！");
			return;
		}

		//事件不为空:将事件转换为Event对象
		Event event= JSONObject.parseObject(record.value().toString(),Event.class);
		//判断对象是否为空
		if(event==null){
			logger.error("消息格式错误！");
			return;
		}

		String htmlUrl= (String) event.getData().get("htmlUrl");
		String fileName= (String) event.getData().get("fileName");
		String suffix= (String) event.getData().get("suffix");
		//生成长图命令
		String cmd=wkImageCommand+" --quality 75 "+htmlUrl+" "+wkImageStorage+"/"+fileName+suffix;
		try {
			Runtime.getRuntime().exec(cmd);
			logger.info("生成长图成功："+cmd);
		} catch (IOException e) {
			logger.error("生成长图失败："+e.getMessage());
		}

	}