利用 HttpClient 上传文件

    /** 
     * Example how to use multipart/form encoded POST request. 
     */  
    public class ClientMultipartFormPost {  
      
        public static void main(String[] args) throws Exception {  
            if (args.length != 1)  {  
                System.out.println("File path not given");  
                System.exit(1);  
            }  
            CloseableHttpClient httpclient = HttpClients.createDefault();  
            try {  
                HttpPost httppost = new HttpPost("http://localhost:8080" +  
                        "/servlets-examples/servlet/RequestInfoExample");  
      
                FileBody img = new FileBody(new File(args[0]));  
                StringBody filename = new StringBody("A binary file of some kind",ContentType.TEXT_PLAIN);  
                StringBody comment = new StringBody("A binary file of some kind",ContentType.TEXT_PLAIN);  
      
                HttpEntity reqEntity = MultipartEntityBuilder.create()  
                        .addPart("img",img)  
                        .addPart("filename",filename)  
                        .addPart("comment",comment)  
                        .build();  
      
      
                httppost.setEntity(reqEntity);  
      
                System.out.println("executing request " + httppost.getRequestLine());  
                CloseableHttpResponse response = httpclient.execute(httppost);  
                try {  
                    System.out.println("----------------------------------------");  
                    System.out.println(response.getStatusLine());  
                    HttpEntity resEntity = response.getEntity();  
                    if (resEntity != null) {  
                        System.out.println("Response content length: " + resEntity.getContentLength());  
                    }  
                    EntityUtils.consume(resEntity);  
                } finally {  
                    response.close();  
                }  
            } finally {  
                httpclient.close();  
            }  
        }  
      
    }