java 上传并压缩图片

最新推荐文章于 2024-07-14 19:55:19 发布

zhao19861029

最新推荐文章于 2024-07-14 19:55:19 发布

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分类专栏： JAVA 文章标签： java string path upload file object

本文链接：https://blog.youkuaiyun.com/zhao19861029/article/details/7794080

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本文介绍了一个用于处理图片上传的Java方法，该方法能够接收multipart格式的HTTP请求，并从中提取上传文件。此外，还实现了图片尺寸调整的功能，确保图片符合特定的宽度和高度要求。文章详细展示了如何创建缩略图并将其保存到指定路径。

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protected Map<String, Object> upload(MultipartHttpServletRequest req) throws IOException {
		String root = PropertiesHelper.getProperty("upload_photo_root");
		String tempPath = PropertiesHelper.getProperty("upload_photo_path");
		Map<String, Object> result = new HashMap<String, Object>();
		if (req.getFile("uploadFile") != null) {
			MultipartFile file = req.getFile("uploadFile");
			
			BufferedImage newImage=getNewImage(file,548,381);
			
			
			if (file.getSize() > 0) {
				String path = root + tempPath;
				path = path.replace('\\', '/');
				File directory = new File(path);
				if (!directory.exists()) {
					directory.mkdirs();
				}
				String pre = "RID" + req.getParameter("reportId") + "_"
						+ String.valueOf(System.currentTimeMillis());
				// File destFile = new File(path + pre +
				// file.getOriginalFilename().toLowerCase());

				// String fileType =
				// file.getOriginalFilename().substring(file.getOriginalFilename().lastIndexOf("."));
				String fileType = ".png";
				File destFile = new File(path + pre + fileType);
				try {
					//FileUtils.writeByteArrayToFile(destFile, file.getBytes());
					ImageIO.write(newImage, "png", destFile);
					result.put("success", true);
					// result.put("url", path + pre +
					// file.getOriginalFilename().toLowerCase());
					result.put("url", path + pre + fileType);
				} catch (IOException e) {
					result.put("success", false);
					e.printStackTrace();
				}
			}
		} else {
			result.put("success", false);
		}
		return result;
	}private  BufferedImage  getNewImage(MultipartFile oldImage,double width,double height) throws IOException{
		/*srcURl 原图地址；deskURL 缩略图地址；comBase 压缩基数；scale 压缩限制(宽/高)比例*/
		
		ByteArrayInputStream bais = new ByteArrayInputStream(oldImage.getBytes()); 
		MemoryCacheImageInputStream mciis = new MemoryCacheImageInputStream(bais);		
		Image src = ImageIO.read(mciis);
		double srcHeight = src.getHeight(null);
		double srcWidth = src.getWidth(null);
		double deskHeight = 0;//缩略图高
		double deskWidth  = 0;//缩略图宽
		if (srcWidth>srcHeight) {
	        
	        if (srcWidth>width) {
	            if (width/height>srcWidth/srcHeight) {
	            	deskHeight = height;
	            	deskWidth = srcWidth/(srcHeight/height);
	            }
	            else {
	            	deskHeight = width/(srcWidth/srcHeight);
	            	deskWidth = width;
	            }
	        }
	        else {
	            
	            if (srcHeight>height) {
	            	deskHeight = height;
	            	deskWidth = srcWidth/(srcHeight/height);
	            }else {
	            	deskHeight=srcHeight;
	                deskWidth=srcWidth;
	            }
	            
	        }
	        
	    }
	    else if(srcHeight>srcWidth)
	    {
	        if (srcHeight>(height)) {
	            if ((height)/width>srcHeight/srcWidth) {
	            	deskHeight = srcHeight/(srcWidth/width);
	            	deskWidth = width;
	            }else {
	            	deskHeight = height;
	                deskWidth = (height)/(srcHeight/srcWidth);
	            }
	        }
	        else {
	            if (srcWidth>width) {
	            	deskHeight = srcHeight/(srcWidth/width);
	                deskWidth = width;
	            }else {
	            	deskHeight=srcHeight;
	                deskWidth=srcWidth;
	            }

	        }
	        
	    }
	    else if (srcWidth==srcHeight) {
	        
	        if (width>=(height)&&srcHeight>(height)) {
	        	deskWidth=(height);
	            deskHeight=(height);
	        }
	        else if (width<=(height)&&srcWidth>width) {
	        	deskWidth=width;
	            deskHeight=width;
	        }
	        else  if (width==(height)&&srcWidth<width) {
	        	deskWidth=srcWidth;
	            deskHeight=srcHeight;
	        }
	        else {
	        	deskHeight=srcHeight;
	            deskWidth=srcWidth;
	        }

	    }
		BufferedImage tag = new BufferedImage((int)deskWidth,(int)deskHeight,
		    BufferedImage.TYPE_3BYTE_BGR);
		tag.getGraphics().drawImage(src, 0, 0, (int)deskWidth, (int)deskHeight, null); //绘制缩小后的图
		return tag;
	}