访问图片支持自定义长宽大小

清疚 2021-11-09 07:50 188阅读 0赞

实现原理：  
在原有的图片上去生成多一份数据变化后的图。其实像七牛这样的加载也是可以按照这个原理进行实现。  
1、配置访问的路径。服务器资源放于本地路径  
project.path = /home/images/  
basePath = /uploadFile/

/**
     * 标注此文件为一个配置项，spring boot才会扫描到该配置。该注解类似于之前使用xml进行配置
     */
    @Configuration
    public class WebMvcConfigurerAdapter extends org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter {
    
    
        @Override
        public void addResourceHandlers(ResourceHandlerRegistry registry) {
            ValueConfig valueConfig = SpringContextHolder.getBean("valueConfig");
            registry.addResourceHandler("/uploadFile/**").addResourceLocations("file:"+valueConfig.getProjectPath()+valueConfig.getBasePath());
            super.addResourceHandlers(registry);
        }
    }

配置拦截器，以便每次请求需要转换的资源进行转换

import com.google.common.collect.Lists;
    import org.apache.commons.lang3.StringUtils;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
    import javax.imageio.ImageIO;
    import javax.servlet.*;
    import javax.servlet.FilterConfig;
    import javax.servlet.http.HttpServletRequest;
    import java.awt.*;
    import java.awt.image.BufferedImage;
    import java.io.File;
    import java.io.IOException;
    import java.util.Arrays;
    import java.util.List;
    
    public class ImagesFilter implements Filter {
        private static Logger log = LoggerFactory.getLogger(ImagesFilter.class);
    
        private String basePath = "/uploadFile/";
        private static List<String> suffixMap = null;
    
    
        static {
            suffixMap = Lists.newArrayList();
            suffixMap.add("jpg");
            suffixMap.add("png");
            suffixMap.add("jpeg");
        }
    
        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
    
            HttpServletRequest httpRequest = (HttpServletRequest) request;
            String w = request.getParameter("w");
            String h = request.getParameter("h");
            String uri = httpRequest.getRequestURI();
            String suffx = uri.substring(uri.lastIndexOf(".") + 1);
    
            //log.info("w:" + w);
            //log.info("h:" + h);
            //log.info("uri:" + uri);
            //log.info("suffx:" + suffx);
            try {
                if (StringUtils.isNumeric(w) && StringUtils.isNumeric(h) && suffixMap.contains(suffx.toLowerCase())) {
                    if (uri.contains("_thumbs_auto")) {
                        chain.doFilter(request, response);
                        return;
                    }
                    ValueConfig valueConfig = SpringContextHolder.getBean("valueConfig");
                    String newuri = "/uploadFile/_thumbs_auto/" + uri.substring(0, uri.lastIndexOf(".")).replaceFirst(basePath, "") + "_" + w + "x" + h + "." + suffx;
                    String filename = valueConfig.getProjectPath() + newuri;
                    //log.info("filename:" + filename);
                    File file = new File(filename);
                    boolean b = false;
                    if (!file.exists()) {
                        String newPath = file.getParent();
                        File p = new File(newPath);
                        if (!p.exists()) {
                            p.mkdirs();
                        }
                        //log.info("newPath:" + newPath);
                        b = thumbnailImage(new File(valueConfig.getProjectPath() + java.net.URLDecoder.decode(uri, "UTF-8")), Integer.parseInt(w), Integer.parseInt(h), filename, false);
                    } else {
                        b = true;
                    }
                    //log.info("b:" + b);
                    if (b) {
                        httpRequest.getRequestDispatcher(newuri).forward(httpRequest, response);
                    }
                } else {
                    chain.doFilter(request, response);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    
        @Override
        public void destroy() {
    
        }
    
        @Override
        public void init(FilterConfig config) throws ServletException {
        }
    
        /**
         * <p>
         * Title: thumbnailImage
         * </p>
         * <p>
         * Description: 根据图片路径生成缩略图
         * </p>
         *
         * @param imgFile  原图片路径
         * @param w        缩略图宽
         * @param h        缩略图高
         * @param filename 生成缩略图的文件名
         * @param force    是否强制按照宽高生成缩略图(如果为false，则生成最佳比例缩略图)
         */
        public static boolean thumbnailImage(File imgFile, int w, int h, String filename, boolean force) {
            if (imgFile.exists()) {
                try {
                    // ImageIO 支持的图片类型 : [BMP, bmp, jpg, JPG, wbmp, jpeg, png, PNG,
                    // JPEG, WBMP, GIF, gif]
                    String types = Arrays.toString(ImageIO.getReaderFormatNames());
                    String suffix = null;
                    // 获取图片后缀
                    if (imgFile.getName().indexOf(".") > -1) {
                        suffix = imgFile.getName().substring(imgFile.getName().lastIndexOf(".") + 1);
                    }// 类型和图片后缀全部小写，然后判断后缀是否合法
                    if (suffix == null || types.toLowerCase().indexOf(suffix.toLowerCase()) < 0) {
                        log.error("Sorry, the image suffix is illegal. the standard image suffix is {}." + types);
                        return false;
                    }
                    log.debug("target image's size, width:{}, height:{}.", w, h);
                    Image img = ImageIO.read(imgFile);
                    int newWidth;
                    int newHeight;
                    BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
                    Graphics g = bi.getGraphics();
                    if (!force) {
                        int imgWidth = img.getWidth(null);
                        int imgHeight = img.getHeight(null);
                        // 根据原图与要求的缩略图比例，找到最合适的缩略图比例
                        double rate1 = ((double) imgWidth) / (double) w;
                        double rate2 = ((double) imgHeight) / (double) h;
    
                        // 根据缩放比率大的进行缩放控制
                        double rate = rate1 < rate2 ? rate1 : rate2;
                        newWidth = (int) ((double) imgWidth / rate);
                        newHeight = (int) ((double) imgHeight / rate);
                        if (rate1 < rate2) {
                            g.drawImage(img, 0, (0 - newHeight / 2 + (h / 2)), newWidth, newHeight, Color.LIGHT_GRAY, null);
                        } else {
                            g.drawImage(img, (0 - newWidth / 2 + (w / 2)), 0, newWidth, newHeight, Color.LIGHT_GRAY, null);
                        }
                    } else {
                        g.drawImage(img, 0, 0, w, h, Color.LIGHT_GRAY, null);
                    }
                    g.dispose();
                    ImageIO.write(bi, suffix, new File(filename));
                    return true;
                } catch (IOException e) {
                    log.error("generate thumbnail image failed.", e);
                }
            } else {
                log.warn("the image is not exist. path:" + imgFile.getPath() + imgFile.getName());
            }
            return false;
        }
    }

最终的实现效果：

url/uploadFile/20190513/146050e3-2f57-4a3e-89cb-75fa89653f21.jpg?w=100&h=100

![732794-20190709151120829-385355610.png][]

url/uploadFile/20190513/146050e3-2f57-4a3e-89cb-75fa89653f21.jpg

![732794-20190709151157962-167857547.png][]

转载于:https://www.cnblogs.com/jimw/p/11157538.html

[732794-20190709151120829-385355610.png]: /images/20211109/31b259954290401f9157aedfddfddf94.png
[732794-20190709151157962-167857547.png]: /images/20211109/00af5845bd494b879a9465d70efc79ac.png