Java处理图片时出现异常

╰半夏微凉° 2022-09-22 03:57 249阅读 0赞

[Java][]处理图片时出现异常

javax.imageio.IIOException: Not a JPEG file: starts with 0x47 0x49  
at com.sun.imageio.plugins.jpeg.JPEGImageReader.readImageHeader(Native Method)  
at com.sun.imageio.plugins.jpeg.JPEGImageReader.readNativeHeader(Unknown Source)  
at com.sun.imageio.plugins.jpeg.JPEGImageReader.checkTablesOnly(Unknown Source)  
at com.sun.imageio.plugins.jpeg.JPEGImageReader.gotoImage(Unknown Source)  
at com.sun.imageio.plugins.jpeg.JPEGImageReader.readHeader(Unknown Source)  
at com.sun.imageio.plugins.jpeg.JPEGImageReader.getWidth(Unknown Source)  
at com.test.filedownloader.ImageHandler.getImageDim(ImageHandler.java:60)  
at com.test.filedownloader.ImageHandler.main(ImageHandler.java:96)  
Exception in thread "main" java.lang.NullPointerException  
at com.test.filedownloader.ImageHandler.getImageDim(ImageHandler.java:70)  
at com.test.filedownloader.ImageHandler.main(ImageHandler.java:96)

![Image 1][]

出现这种错误是因为将gif 图片后缀改成了jpg

解决办法：

根据文件的前面几个字节，判断文件类型

/*
         * 判断图片的原始类型 2016-6-27
         */
        private String getFileSuffix(final String path) throws IOException {
    		String result = "";
    		String hex="";
    		if (path != null) {
    			File image=new File(path);
    			InputStream is = new FileInputStream(image);
    			byte[] bt = new byte[2];  
    			is.read(bt); 
    			hex=bytesToHexString(bt);
    			is.close();
    			if(hex.equals("ffd8")){
    				result="jpg";
    			}else if(hex.equals("4749")){
    				result="gif";
    			}else if(hex.equals("8950")){
    				result="png";
    			}
    		}
    		return result;
    	}  
        public static String bytesToHexString(byte[] src) {  
            StringBuilder stringBuilder = new StringBuilder();  
            if (src == null || src.length <= 0) {  
                return null;  
            }  
            for (int i = 0; i < src.length; i++) {
                int v = src[i] & 0xFF;  
                String hv = Integer.toHexString(v);  
                if (hv.length() < 2) {  
                    stringBuilder.append(0);  
                }  
                stringBuilder.append(hv);  
            }  
            return stringBuilder.toString();  
        }

[Java]: http://lib.csdn.net/base/17
[Image 1]: