Java 中HttpURLConnection附件上传的实例详解

Java 中HttpURLConnection附件上传的实例详解

整合了一个自己写的采用Http做附件上传的工具，分享一下！

示例代码：

/**
* 以Http协议传输文件
*
* @author mingxue.zhang@163.com
*
*/
public class HttpPostUtil {

private final static char[] MULTIPART_CHARS = "-_1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
     .toCharArray();

private URL url;
 private HttpURLConnection conn;
 private String boundary = null;
 private Map<String, String> textParams = new HashMap<String, String>();
 private Map<String, File> fileparams = new HashMap<String, File>();

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

// 重新设置要请求的服务器地址，即上传文件的地址。
 public void setUrl(String url) throws Exception {
   this.url = new URL(url);
 }

// 增加一个普通字符串数据到form表单数据中
 public void addTextParameter(String name, String value) {
   textParams.put(name, value);
 }

// 增加一个文件到form表单数据中
 public void addFileParameter(String name, File value) {
   fileparams.put(name, value);
 }

// 清空所有已添加的form表单数据
 public void clearAllParameters() {
   textParams.clear();
   fileparams.clear();
 }

/**
  * 发送数据到服务器
  *
  * @return 一个字节包含服务器的返回结果的数组
  * @throws Exception
  */
 public byte[] send() throws Exception {
   initConnection();
   try {
     conn.connect();
   } catch (SocketTimeoutException e) {
     throw new Exception(e);
   }

OutputStream connOutStream = new DataOutputStream(
       conn.getOutputStream());

writeFileParams(connOutStream);
   writeStringParams(connOutStream);
   writesEnd(connOutStream);

InputStream responseInStream = conn.getInputStream();
   ByteArrayOutputStream responseOutStream = new ByteArrayOutputStream();
   int len;
   byte[] bufferByte = new byte[1024];
   while ((len = responseInStream.read(bufferByte)) != -1) {
     responseOutStream.write(bufferByte, 0, len);
   }
   responseInStream.close();
   connOutStream.close();

conn.disconnect();
   byte[] resultByte = responseOutStream.toByteArray();
   responseOutStream.close();
   return resultByte;
 }

// 文件上传的connection的一些必须设置
 private void initConnection() throws Exception {
   StringBuffer buf = new StringBuffer("----");
   Random rand = new Random();
   for (int i = 0; i < 15; i++) {
     buf.append(MULTIPART_CHARS[rand.nextInt(MULTIPART_CHARS.length)]);
   }
   this.boundary = buf.toString();

conn = (HttpURLConnection) this.url.openConnection();
   conn.setDoOutput(true);
   conn.setUseCaches(false);
   conn.setConnectTimeout(3 * 60 * 1000); // 连接超时为10秒
   conn.setRequestMethod("POST");
   conn.setRequestProperty("Content-Type",
       "multipart/form-data; boundary=" + boundary);
 }

// 普通字符串数据
 private void writeStringParams(OutputStream out) throws Exception {
   Set<String> keySet = textParams.keySet();
   for (Iterator<String> it = keySet.iterator(); it.hasNext();) {
     String name = it.next();
     String value = textParams.get(name);

out.write(("--" + boundary + "\r\n").getBytes());
     out.write(("Content-Disposition: form-data; name=\"" + name + "\"\r\n")
         .getBytes());
     out.write(("\r\n").getBytes());
     out.write((encode(value) + "\r\n").getBytes());
   }
 }

// 文件数据
 private void writeFileParams(OutputStream out) throws Exception {
   Set<String> keySet = fileparams.keySet();
   for (Iterator<String> it = keySet.iterator(); it.hasNext();) {
     String name = it.next();
     File value = fileparams.get(name);

out.write(("--" + boundary + "\r\n").getBytes());
     out.write(("Content-Disposition: form-data; name=\"" + name
         + "\"; filename=\"" + encode(value.getName()) + "\"\r\n")
         .getBytes());
     out.write(("Content-Type: " + getContentType(value) + "\r\n")
         .getBytes());
     out.write(("Content-Transfer-Encoding: " + "binary" + "\r\n")
         .getBytes());

out.write(("\r\n").getBytes());

FileInputStream inStream = new FileInputStream(value);
     int bytes = 0;
     byte[] bufferByte = new byte[1024];
     while ((bytes = inStream.read(bufferByte)) != -1) {
       out.write(bufferByte, 0, bytes);
     }
     inStream.close();

out.write(("\r\n").getBytes());
   }
 }

// 添加结尾数据
 private void writesEnd(OutputStream out) throws Exception {
   out.write(("--" + boundary + "--" + "\r\n").getBytes());
   out.write(("\r\n").getBytes());
 }

// 获取文件的上传类型，图片格式为image/png,image/jpg等。非图片为application/octet-stream
 private String getContentType(File f) throws Exception {
   String fileName = f.getName();
   if (fileName.endsWith(".jpg")) {
     return "image/jpeg";
   } else if (fileName.endsWith(".png")) {
     return "image/png";
   }
   return "application/octet-stream";
 }

// 对包含中文的字符串进行转码，此为UTF-8。服务器那边要进行一次解码
 private String encode(String value) throws Exception {
   return URLEncoder.encode(value, "UTF-8");
 }

}

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来源：http://zmx.iteye.com/blog/2211633