post  上传图片

写在前面的：

代码中标黄的地方“Content-Type: image/jpeg” ，服务器端得到文件才会是“xxx.jpeg”;

网上大多数代码都是“Content-Type: application/octet-stream” ，这时服务器端得到的文件是“xxx.octet-stream”

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;




public class PostFileTest {
	

	public static void main(String[] args) {
		
		String filePath = "E:\\2.jpg";
		String urlS = "http://localhost:8070/SpringMVCTest/hellofile/uploadfile";
		
		
		try{
			String boundary = "Boundary-b1ed-4060-99b9-fca7ff59c113"; //Could be any string
			String Enter = "\r\n";
			
			File file = new File(filePath);
			FileInputStream fis = new FileInputStream(file);
			
			URL url = new URL(urlS);
			HttpURLConnection conn = (HttpURLConnection)url.openConnection();
			conn.setDoOutput(true);
			conn.setDoInput(true);
			conn.setRequestMethod("POST");
			conn.setUseCaches(false);
			conn.setInstanceFollowRedirects(true);
			conn.setRequestProperty("Content-Type","multipart/form-data;boundary=" + boundary); 
			
			conn.connect();
			
			DataOutputStream dos = new DataOutputStream(conn.getOutputStream());
		  
		  //part 1
			String part1 =  "--" + boundary + Enter
					+ "Content-Type: image/jpeg" + Enter
					+ "Content-Disposition: form-data; filename=\""+file.getName()+"\"; name=\"file\"" + Enter + Enter;
		  //part 2
			String part2 = Enter
					+ "--" + boundary + Enter
					+ "Content-Type: text/plain" + Enter
					+ "Content-Disposition: form-data; name=\"dataFormat\"" + Enter + Enter
					+ "hk" + Enter
					+ "--" + boundary + "--";
			System.out.println("part1: "+part1);
			System.out.println("part2: "+part2);
			
			byte[] fileBytes = new byte[fis.available()];
			fis.read(fileBytes);
			
			dos.writeBytes(part1);
			dos.write(fileBytes);
			dos.writeBytes(part2);
			
			dos.flush();
			dos.close();
			fis.close();
			
			System.out.println("status code: "+conn.getResponseCode());
			// 得到响应流
			InputStream responseStream = conn.getInputStream();
			// 获取响应
			BufferedReader reader = new BufferedReader(new InputStreamReader(responseStream));
			String line;
			StringBuilder message = new StringBuilder();
			while ((line = reader.readLine()) != null) {
				message.append(line);
			}
			// 获取返回信息
			//return message.toString();
			System.out.println("return: "+message.toString());
            
		
			conn.disconnect();
			
		}catch(Exception e){
			e.printStackTrace();
		}



	}

}

参考

java 发送文件（Http Post），带其他参数

Java POST请求发送文件同时发送参数

其他上次图片文件的方式：

HttpClient用法--这一篇全了解（内含例子）

如何用java网络编程实现本地文件上传到服务器？