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img标签显示图片方法总结

2019-08-26 06:11:44来源：博客园阅读 ()

img标签显示图片方法总结

1、通过图片在项目下的可访问路径。

　　例如：<img src='../assets/imags/xxx.jpg' />

2、通过一个下载器链接，读取（文件）服务器上的图片资源。

　　例如：<img src='http://ip:port/projectName/getImageServlet?imagesPath' />

　　后端代码：

　　protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       String imagePath = "D://牙牙牙白.gif";
       String contentType = "";
       String lowerPath = imagePath.toLowerCase();
       if(lowerPath.endsWith("jpg") || lowerPath.endsWith("jpe") || lowerPath.endsWith("jpeg")){
           contentType = "image/jpeg;charset=utf-8";
       } else if (lowerPath.endsWith("png")) {
           contentType = "image/png;charset=utf-8";
       } else if (lowerPath.endsWith("bmp")) {
           contentType = "image/bmp;charset=utf-8";
       } else if (lowerPath.endsWith("gif")) {
           contentType = "image/gif;charset=utf-8";
       }
       response.setContentType(contentType);

       // 文件流的方式
       InputStream in = new FileInputStream(imagePath);// 输入流
       OutputStream out = response.getOutputStream();// 输出流

       // 边读边写
       byte[] bt = new byte[1024];
       int length = 0;
       while ((length = in.read(bt)) != -1) {
           out.write(bt, 0, length);
       }
       // 关闭流
       in.close();
       out.flush();
       out.close();
   }　　

3、base64加密数据填充法。

　　例如：<img src="data:image/gif;base64,R0lGODlhHAAmAKIHAKqqqsvLy0hISObm5vf394uLiwAAAP///yH5B…　　EoqQqJKAIBaQOVKHAXr3t7txgBjboSvB8EpLoFZywOAo3LFE5lYs/QW9LT1TRk1V7S2xYJADs=">

　　后端代码：

　　public static String getImageBase64() throws Exception{
       String imagePath = "D://牙牙牙白.gif";
       String contentType = "";
       String lowerPath = imagePath.toLowerCase();
       if(lowerPath.endsWith("jpg") || lowerPath.endsWith("jpe") || lowerPath.endsWith("jpeg")){
           contentType = "image/jpeg";
       } else if (lowerPath.endsWith("png")) {
           contentType = "image/png";
       } else if (lowerPath.endsWith("bmp")) {
           contentType = "image/bmp";
       } else if (lowerPath.endsWith("gif")) {
           contentType = "image/gif";
       }

       InputStream in = new FileInputStream(imagePath);// 输入流
       ByteArrayOutputStream out = new ByteArrayOutputStream(); // 输出流
       // 边读边写
       byte[] buffer = new byte[1024];
       int length = 0;
       while ((length = in.read(buffer)) != -1) {
           out.write(buffer, 0, length);
       }
       // 关闭流
       in.close();
       out.flush();
       out.close();

       // import sun.misc.BASE64Encoder
       BASE64Encoder encoder = new BASE64Encoder();
       String imageBase64 = new String(encoder.encode(out.toByteArray()));
       String imageSrc = "data:" + contentType + ";base64," + imageBase64;

       return imageSrc;
   }