parampart.java

来自「很好的文件处理程序」· Java 代码 · 共 101 行

// Copyright (C) 1999-2001 by Jason Hunter <jhunter_AT_acm_DOT_org>.
// All rights reserved.  Use of this class is limited.
// Please see the LICENSE for more information.

package com.oreilly.servlet.multipart;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import javax.servlet.ServletInputStream;

/**
 * A <code>ParamPart</code> is an upload part which represents a normal 
 * <code>INPUT</code> (for example a non <code>TYPE="file"</code>) form
 * parameter.
 * 
 * @author Geoff Soutter
 * @author Jason Hunter
 * @version 1.1, 2002/04/30, added better encoding support, thanks to
 *                           Changshin Lee
 * @version 1.0, 2000/10/27, initial revision
 */
public class ParamPart extends Part {
  
  /** contents of the parameter */
  private byte[] value;

  private String encoding;

  /**
   * Constructs a parameter part; this is called by the parser.
   * 
   * @param name the name of the parameter.
   * @param in the servlet input stream to read the parameter value from.
   * @param boundary the MIME boundary that delimits the end of parameter value.
   * @param encoding the byte-to-char encoding to use by default
   * value.
   */
  ParamPart(String name, ServletInputStream in, 
            String boundary, String encoding) throws IOException {
    super(name);
    this.encoding = encoding;

    // Copy the part's contents into a byte array
    PartInputStream pis = new PartInputStream(in, boundary);
    ByteArrayOutputStream baos = new ByteArrayOutputStream(512);
    byte[] buf = new byte[128];
    int read;
    while ((read = pis.read(buf)) != -1) {
      baos.write(buf, 0, read);
    }
    pis.close();
    baos.close();
    
    // save it for later
    value = baos.toByteArray();
  }

  /** 
   * Returns the value of the parameter as an array of bytes or a zero length 
   * array if the user entered no value for this parameter.
   * 
   * @return value of parameter as raw bytes
   */
  public byte[] getValue() {
    return value;
  }
  
  /** 
   * Returns the value of the parameter in as a string (using the
   * parser-specified encoding to convert from bytes) or the empty string
   * if the user entered no value for this parameter.
   * 
   * @return value of parameter as a string.
   */
  public String getStringValue() 
      throws UnsupportedEncodingException {
    return getStringValue(encoding);
  }
  
  /** 
   * Returns the value of the parameter in the supplied encoding
   * or empty string if the user entered no value for this parameter.
   * 
   * @return value of parameter as a string.
   */
  public String getStringValue(String encoding) 
      throws UnsupportedEncodingException {
    return new String(value, encoding);
  }
  
  /**
   * Returns <code>true</code> to indicate this part is a parameter.
   * 
   * @return true.
   */
  public boolean isParam() {
    return true;
  }
}