7.8生成长图

生成长图的手段，服务端通过工具读取HTML模板中的内容生成长图。
官网https://wkhtmltopdf.org，下载安装，把安装目录添加到环境变量。
新建data\wk-images和D:\javing\workspace\data\wk-pdfs目录，打开命令窗口，输入

C:\Users\hp>wkhtmltopdf http://www.nowcoder.com d:/WorkPlace/data/wk-pdf/1.pdf

生成图片,以压缩的形式：

wkhtmltoimage --quality 75 https://www.nowcoder.com d:/WorkPlace/data/wk-pdfs/2.png

测试类：

public class WkTests {

    public static void main(String[] args) {
        String cmd = "d:/WorkPlace/wkhtmltopdf/bin/wkhtmltoimage --quality 75  https://www.nowcoder.com d:/WorkPlace/data/wk-image/1.png";
        try {
            Runtime.getRuntime().exec(cmd);//执行上面的cmd命令
            System.out.println("ok.");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

模拟分享功能

系统上线之后，Linux的路径不一样，所以上面测试类中的路径地址要更换。
所以配置类中新增：

# wk
wk.image.command=d:/WorkPlace/wkhtmltopdf/bin/wkhtmltoimage
wk.image.storage=d:/WorkPlace/data/wk-images

Config配置

@Configuration
public class WKConfig {

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

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

    //服务启动的时候创建目录
    @PostConstruct
    public void init(){
        //创建目录
        File file = new File(wkImageStorage);
        if (!file.exists()){
            file.mkdir();
            logger.info("创建wk目录图片:"+wkImageStorage);
        }

    }
}

EventConsumer中新增消费分享事件,后面controller才能发送事件到es服务器中：

    //消费分享事件
    @KafkaListener(topics = {TOPIC_SHARE})
    public void handleShareMessage(ConsumerRecord record){
        if (record == null || record.value() == null){
            logger.error("消息的内容为空");
            return;
        }
        Event event = JSONObject.parseObject(record.value().toString(),Event.class);
        if (event == null){
            logger.error("消息的格式错误");
            return;
        }

        String htmlUrl = (String) event.getData().get("htmlUrl");
        String fileName = (String) event.getData().get("fileName");
        String suffix = (String) event.getData().get("suffix");

        //取到值之后，拼出命令执行
        String cmd = wkImageCommand + " --quality 75 "+htmlUrl+" "+wkImageStorage+"/"+fileName+suffix;
        try {
            Runtime.getRuntime().exec(cmd);
            logger.info("生成长图成功,命令是："+cmd);
        } catch (IOException e) {
            logger.error("生成长图失败："+e.getMessage());
        }
    }

ShareController

@Controller
public class ShareController implements CommunityConstant {
    private static final Logger logger = LoggerFactory.getLogger(WKConfig.class);
    //前端一访问就生成一个图片，异步最好，丢给kafka就中，
    @Autowired
    private EventProducer eventProducer;

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

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

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

    @RequestMapping(path = "/share",method = RequestMethod.GET)
    @ResponseBody
    public String share(String htmlUrl){
        //随机文件名，不然容易重名
        String fileName = CommunityUtil.generateUUID();
        Event event = new Event()
                .setTopic(TOPIC_SHARE)
                .setData("htmlUrl",htmlUrl)
                .setData("fileName",fileName)
                .setData("suffix",".png");
        eventProducer.fireEvent(event); //异步生成长图

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


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

    //获取长图
    @RequestMapping(path = "/share/image/{fileName}",method = RequestMethod.GET)
    public void getShareImage(@PathVariable("fileName") String fileName, HttpServletResponse response){
        if (StringUtils.isBlank(fileName)){
            throw new IllegalArgumentException("文件名不能为空");
        }
        response.setContentType("image/png");

        File file = new File(wkImageStorage+"/"+fileName+".png");
        try {
            ServletOutputStream os = response.getOutputStream();
            FileInputStream fis = new FileInputStream(file);
            //缓冲区
            byte[] buffer = new byte[1024];
            //游标
            int b = 0 ;
            while ((b = fis.read(buffer) )!= -1){
                //不等于-1,表示确实读到数据了
                //把游标b读到的fis数据读给os
                os.write(buffer,0,b);//防止最后一次每到1024，所以这有个范围
            }
        } catch (IOException e) {
            logger.error("获取长图失败："+e.getMessage());
        }
    }
}

测试地址：
http://localhost:8080/community/share?htmlUrl=http://www.nowcoder.com

本地有文件，输入http://localhost:8080/community/share/image/4a945261819b477fa02de82fa7aa6c27 可以访问到生成的图片，OK。

标签：String,image,wk,成长,fileName,public,7.8,logger
来源： https://blog.csdn.net/weixin_44114392/article/details/112811398