问答平台（7），生成长图

wkhtmltopdf

wkhtmltopdf url file

wkhtmltoimage url file

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wkhtmltopdf https://www.nowcoder.com d:/work/data/wk-pdfs/1.pdf
wkhtmltoimage https://www.nowcoder.com d:/work/data/wk-images/1.png
wkhtmltoimage --quality 75 https://www.nowcoder.com d:/work/data/wk-images/2.png

java

Runtime().getRuntime().exec()

测试类

WkTests: 新增

public class WkTests {

    public static void main(String[] args) {
        String cmd = "d:/work/wkhtmltopdf/bin/wkhtmltoimage --quality 75 https://www.nowcoder.com d:/work/data/wk-images/3.png";
        try {
            Runtime.getRuntime().exec(cmd);
            System.out.println("ok");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

项目开发

配置文件

application-develop.properties: 添加内容

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

config

WkConfig: 新增

@Configuration
public class WkConfig {

    private static final 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);
        }
    }
}

表现层

ShareController: 新增

@Controller
public class ShareController implements CommunityConstant {

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

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

        // 异步生成长图
        Event event = new Event()
                .setTopic(TOPIC_SHARE)
                .setData("htmlUrl", htmlUrl)
                .setData("fileName", fileName)
                .setData("suffix", ".png");
        eventProducer.fireEvent(event);

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

消费事件

EventConsumer: 添加

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

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

// 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");

    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.info("生成长图失败: " + e.getMessage());
    }
}