Explication détaillée du téléchargement de pièces jointes HttpURLConnection en Java

Cet article présente principalement des informations pertinentes sur les exemples détaillés de téléchargement de pièces jointes HttpURLConnection en Java. J'espère que grâce à cet article, tout le monde pourra maîtriser ces connaissances. Les amis dans le besoin pourront se référer à

HttpURLConnection en Java. Explication détaillée des exemples de téléchargement de pièces jointes

Intégration d'un outil que j'ai écrit en utilisant Http pour le téléchargement de pièces jointes, partagez-le !

Exemple de code :

/** 
 * 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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