java Post 上传文件

package com.ckn.web.main;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class JavaDirectUpload {
	
	public static void uploadFile(String urlStr, String  formName,String fileName) {
		try {
			// 换行符
			final String newLine = "\r\n";
			final String boundaryPrefix = "--";
			// 定义数据分隔线
			String BOUNDARY = "========7d4a6d158c9";
			// 服务器的域名
			URL url = new URL(urlStr);
			HttpURLConnection conn = (HttpURLConnection) url.openConnection();
			// 设置为POST情
			conn.setRequestMethod("POST");
			// 发送POST请求必须设置如下两行
			conn.setDoOutput(true);
			conn.setDoInput(true);

			// 设置请求头参数
			conn.setRequestProperty("connection", "Keep-Alive");
			conn.setRequestProperty("Charsert", "UTF-8");
			conn.setRequestProperty("Content-Type","multipart/form-data; boundary=" + BOUNDARY);
			OutputStream out = conn.getOutputStream();
			// 上传文件
			File file = new File(fileName);
			StringBuilder sb = new StringBuilder();
			sb.append(boundaryPrefix);
			sb.append(BOUNDARY);
			sb.append(newLine);
			// 文件参数,photo参数名可以随意修改
			sb.append("Content-Disposition: form-data;name=\""+formName+"\";filename=\""+ fileName + "\"" + newLine);
			sb.append("Content-Type:application/octet-stream");
			// 参数头设置完以后需要两个换行，然后才是参数内容
			sb.append(newLine);
			sb.append(newLine);
			// 将参数头的数据写入到输出流中
			out.write(sb.toString().getBytes());
			// 数据输入流,用于读取文件数据
			DataInputStream in = new DataInputStream(new FileInputStream(file));
			byte[] bufferOut = new byte[1024];
			int bytes = 0;
			// 每次读1KB数据,并且将文件数据写入到输出流中
			while ((bytes = in.read(bufferOut)) != -1) {
				out.write(bufferOut, 0, bytes);
			}
			// 最后添加换行
			out.write(newLine.getBytes());
			in.close();
			// 定义最后数据分隔线，即--加上BOUNDARY再加上--。
			byte[] end_data = (newLine + boundaryPrefix + BOUNDARY
					+ boundaryPrefix + newLine).getBytes();
			// 写上结尾标识
			out.write(end_data);
			out.flush();
			out.close();
			
			//定义BufferedReader输入流来读取URL的响应
			BufferedReader reader = new BufferedReader(new InputStreamReader(
			conn.getInputStream()));
			String line = null;
			while ((line = reader.readLine()) != null) {
				System.out.println(line);
			}
		} catch (Exception e) {
			System.out.println("发送POST请求出现异常！" + e);
			e.printStackTrace();
		}
	}
	
	public static void main(String[] args){
		String wxUrlStr="https://api.weixin.qq.com/cgi-bin/media/uploadimg?access_token=auto_581";
		String formName="media";
		String fileFullPath="D:\\Users\\ex-chengyibo600\\Desktop\\TRANSFILE\\newCarLoan\\1447738780798_Jellyfish.jpg";
		uploadFile(wxUrlStr,formName,fileFullPath);
	}

}