用HttpURLConnection提交文件

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.InputStream;

import java.io.OutputStream;

import java.net.HttpURLConnection;

import java.net.URL;

import java.util.HashMap;

import java.util.LinkedList;

import java.util.List;

import java.util.Map;

import java.util.UUID;

public class HttpMultipart

{

public static void main(String[] args) throws Exception

{

String link = “http://www.xxx.com/upload“;

HttpMultipart hm = new HttpMultipart(link).addParameter(“file”, new File(“d:\xxx.doc”)).addParameter(“other”,”somevalue”);

String result = new String(hm.send());

hm.clearParameter();

System.out.println(result);

}

private URL url;// 链接URL

private String boundary = "--------" + UUID.randomUUID().toString().replace("-", "");// HTTP报文分隔符

private Map<String, List<String>> textParams = new HashMap<String, List<String>>();// 字符串表单存储结构

private Map<String, List<File>> fileParams = new HashMap<String, List<File>>();// 文件表单存储结构

public HttpMultipart(String url) throws Exception
{
this.url = new URL(url);
}

protected Map<String, List<File>> getFileParams()
{
return fileParams;
}

protected Map<String, List<String>> getTextParams()
{
return textParams;
}

// 增加一个普通字符串数据到form表单数据中
public HttpMultipart addParameter(String name, String value)
{
List<String> list = textParams.get(name);
if (list == null)
{
list = new LinkedList<String>();
list.add(value);
textParams.put(name, list);
}
else
{
list.add(value);
}
return this;
}

// 增加一个文件到form表单数据中
public HttpMultipart addParameter(String name, File value)
{
List<File> list = fileParams.get(name);
if (list == null)
{
list = new LinkedList<File>();
list.add(value);
fileParams.put(name, list);
}
else
{
list.add(value);
}
return this;
}

// 删除指定的字符串参数
public HttpMultipart removeTextParameter(String name)
{
textParams.remove(name);
return this;
}

// 删除指定的字符串参数（如果是数组，指定数组下标）
public HttpMultipart removeTextParameter(String name, int index)
{
List<String> list = textParams.get(name);
if (list != null)
{
if (list.size() > index)
{
list.remove(index);
}
if (list.size() == 0)
{
textParams.remove(name);
}
}
return this;
}

// 删除指定的文件参数
public HttpMultipart removeFileParameter(String name)
{
fileParams.remove(name);
return this;
}

// 删除指定的文件参数（如果是数组，指定数组下标）
public HttpMultipart removeFileParameter(String name, int index)
{
List<File> list = fileParams.get(name);
if (list != null)
{
if (list.size() > index)
{
list.remove(index);
}
if (list.size() == 0)
{
fileParams.remove(name);
}
}
return this;
}

// 清除字符串参数
public HttpMultipart clearTextParameter()
{
textParams.clear();
return this;
}

// 清除文件参数
public HttpMultipart clearFileParameter()
{
fileParams.clear();
return this;
}

// 清除所有参数
public HttpMultipart clearParameter()
{
textParams.clear();
fileParams.clear();
return this;
}

// 发送数据到服务器，返回一个字节包含服务器的返回结果的数组
public byte[] send() throws Exception
{
HttpURLConnection connection = (HttpURLConnection) url.openConnection();

long length = getLength();
connection.setDoOutput(true);
connection.setUseCaches(false);
connection.setConnectTimeout(10000); // 连接超时为10秒
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
connection.setRequestProperty("Content-Length", length + "");
// connection.setFixedLengthStreamingMode((int) length);//设置上传流大小，防止OutOfMemoryError；但是Int的最大值只支持2G，所以暂时不用；
connection.setChunkedStreamingMode(65536);// 设置上传流区块大小，防止OutOfMemoryError

connection.connect();
OutputStream o = connection.getOutputStream();
writeFileParams(o);
writeTextParams(o);
paramsEnd(o);
InputStream in = connection.getInputStream();
ByteArrayOutputStream out = new ByteArrayOutputStream();
transfer(in, out, 1024);
out.close();
in.close();
connection.disconnect();
return out.toByteArray();
}

// 获取一个字符串表单的长度
private long getParamLength(String name, String value) throws Exception
{
return 49 + boundary.length() + name.length() + value.getBytes().length;
}

// 获取一个文件表单的长度
private long getParamLength(String name, File value) throws Exception
{
return 102 + boundary.length() + name.length() + value.getName().getBytes().length + value.length();
}

// 获取报文的长度
private long getLength() throws Exception
{
long length = 0;
for (String name : textParams.keySet())
{
List<String> list = textParams.get(name);
for (String value : list)
{
length = length + getParamLength(name, value);
}
}
for (String name : fileParams.keySet())