上传文件(同事写的,个人觉得写的蛮规范，拿来学习学习！)

import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Iterator;
import java.util.Map;
import java.util.UUID;

import org.apache.log4j.Logger;
import org.springframework.web.multipart.MultipartFile;

public class UploadUtil
{
private static UploadUtil uploadUtil;
private static final String BOUNDARY = UUID.randomUUID().toString(); // 边界标识
// 随机生成
private static final String PREFIX = "--";
private static final String LINE_END = " ";
private static final String CONTENT_TYPE = "multipart/form-data"; // 内容类型
private static final Logger logger = Logger.getLogger(UploadUtil.class);

/**
* 单例模式获取上传工具类
*
* @return
*/
public static UploadUtil getInstance()
{
if (null == uploadUtil)
{
uploadUtil = new UploadUtil();
}
return uploadUtil;
}

private static int readTimeOut = 1000 * 1000; // 读取超时
private static int connectTimeout = 1000 * 1000; // 超时时间

/***
* 请求使用多长时间
*/
private static int requestTime = 0;

private static final String CHARSET = "utf-8"; // 设置编码

/***
* 上传成功
*/
public static final int UPLOAD_SUCCESS_CODE = 1;

/**
* 文件不存在
*/
public static final int UPLOAD_FILE_NOT_EXISTS_CODE = 2;

/**
* 服务器出错
*/
public static final int UPLOAD_SERVER_ERROR_CODE = 3;
protected static final int WHAT_TO_UPLOAD = 1;
protected static final int WHAT_UPLOAD_DONE = 2;

/**
* 上传文件
*/
public static String uploadFile(MultipartFile file, String fileKey, String RequestURL, Map<String, String> param)
{

logger.info("图片上传请求地址:"+RequestURL);
String result = null;
requestTime = 0;

long requestTime = System.currentTimeMillis();
long responseTime = 0;

try
{
URL url = new URL(RequestURL);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(readTimeOut);
conn.setConnectTimeout(connectTimeout);
conn.setDoInput(true); // 允许输入流
conn.setDoOutput(true); // 允许输出流
conn.setUseCaches(false); // 不允许使用缓存
conn.setRequestMethod("POST"); // 请求方式
conn.setRequestProperty("Charset", CHARSET); // 设置编码
conn.setRequestProperty("connection", "keep-alive");
conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
conn.setRequestProperty("Content-Type", CONTENT_TYPE + ";boundary=" + BOUNDARY);

/**
* 当文件不为空，把文件包装并且上传
*/
DataOutputStream dos = new DataOutputStream(conn.getOutputStream());
StringBuffer sb = null;
String params = "";

/***
* 以下是用于上传参数
*/
if (param != null && param.size() > 0)
{
Iterator<String> it = param.keySet().iterator();
while (it.hasNext())
{
sb = null;
sb = new StringBuffer();
String key = it.next();
String value = param.get(key);
sb.append(PREFIX).append(BOUNDARY).append(LINE_END);
sb.append("Content-Disposition: form-data; name="").append(key).append(""").append(LINE_END).append(LINE_END);
sb.append(value).append(LINE_END);
params = sb.toString();
logger.error(key + "=" + params + "##");
dos.write(params.getBytes());
}
}

sb = null;
params = null;
sb = new StringBuffer();
/**
* 这里重点注意： name里面的值为服务器端需要key 只有这个key 才可以得到对应的文件
* filename是文件的名字，包含后缀名的 比如:abc.png
*/
sb.append(PREFIX).append(BOUNDARY).append(LINE_END);
sb.append("Content-Disposition:form-data; name="" + fileKey + ""; filename="" + file.getOriginalFilename() + """ + LINE_END);
sb.append("Content-Type:image/pjpeg" + LINE_END); // 这里配置的Content-type很重要的
// ，用于服务器端辨别文件的类型的
sb.append(LINE_END);
params = sb.toString();
sb = null;
dos.write(params.getBytes());

/** 上传文件 */
InputStream is = file.getInputStream();
byte[] bytes = new byte[1024];
int len = 0;
while ((len = is.read(bytes)) != -1)
{
dos.write(bytes, 0, len);
}
is.close();

dos.write(LINE_END.getBytes());
byte[] end_data = (PREFIX + BOUNDARY + PREFIX + LINE_END).getBytes();
dos.write(end_data);
dos.flush();
//
// dos.write(tempOutputStream.toByteArray());
/**
* 获取响应码 200=成功 当响应成功，获取响应的流
*/
int res = conn.getResponseCode();
logger.info("图片接口返回的Code:"+res);
responseTime = System.currentTimeMillis();
requestTime = (int) ((responseTime - requestTime) / 1000);
if (res == 200)
{
InputStream input = conn.getInputStream();
StringBuffer sb1 = new StringBuffer();
int ss;
while ((ss = input.read()) != -1)
{
sb1.append((char) ss);
}
result = sb1.toString();
}
}
catch (MalformedURLException e)
{
logger.error("文件读写异常", e);
}
catch (IOException e)
{
logger.error("文件读写异常", e);
}

return result;
}

/**
* 获取上传使用的时间
*
* @return
*/
public static int getRequestTime()
{
return requestTime;
}
}