request.java

实现图书管理

package mypkg.jspsmart.upload;

import java.util.Enumeration;
import java.util.Hashtable;

/**
 * The equivalent of ServletRequest Class. This is a dependant object wich can't
 * be directly instantiate.
 * 
 * @author jimshen
 * 
 */
public class Request {
	private Hashtable parameters;

	private int counter;

	Request() {
		parameters = new Hashtable();
		counter = 0;
	}

	protected void putParameter(String name, String value) {
		if (name == null) {
			throw new IllegalArgumentException(
					"The name of an element cannot be null.");
		}
		if (parameters.containsKey(name)) {
			Hashtable hashtable = (Hashtable) parameters.get(name);
			hashtable.put(new Integer(hashtable.size()), value);
		} else {
			Hashtable hashtable1 = new Hashtable();
			hashtable1.put(new Integer(0), value);
			parameters.put(name, hashtable1);
			counter++;
		}
	}

	/**
	 * Returns the value of a request parameter as a String, or null if the
	 * parameter does not exist. Request parameters are extra information sent
	 * with the request. You should only use this method when you are sure the
	 * parameter has only one value. If the parameter might have more than one
	 * value, use getParameterValues(java.lang.String).
	 * 
	 * If you use this method with a multivalued parameter, the value returned
	 * is equal to the first value in the array returned by getParameterValues.
	 * 
	 * If the parameter data was sent in the request body, such as occurs with
	 * an HTTP POST request, then reading the body directly via #getInputStream
	 * or #getReader can interfere with the execution of this method.
	 * 
	 * @param name
	 *            a String specifying the name of the parameter
	 * @return a String representing the single value of the parameter
	 * @see getParameterValues(java.lang.String)
	 */
	public String getParameter(String name) {
		if (name == null) {
			throw new IllegalArgumentException(
					"Form's name is invalid or does not exist (1305).");
		}
		Hashtable hashtable = (Hashtable) parameters.get(name);
		if (hashtable == null) {
			return null;
		} else {
			return (String) hashtable.get(new Integer(0));
		}
	}

	/**
	 * Returns an Enumeration of String objects containing the names of the
	 * parameters contained in this request. If the request has no parameters,
	 * the method returns an empty Enumeration.
	 * 
	 * @return an Enumeration of String objects, each String containing the name
	 *         of a request parameter; or an empty Enumeration if the request
	 *         has no parameters
	 * 
	 */
	public Enumeration getParameterNames() {
		return parameters.keys();
	}

	/**
	 * Returns an array of String objects containing all of the values the given
	 * request parameter has, or null if the parameter does not exist. If the
	 * parameter has a single value, the array has a length of 1.
	 * 
	 * 
	 * @param name
	 *            a String containing the name of the parameter whose value is
	 *            requested
	 * @return an array of String objects containing the parameter's values
	 * @see getParameter(java.lang.String)
	 */
	public String[] getParameterValues(String name) {
		if (name == null) {
			throw new IllegalArgumentException(
					"Form's name is invalid or does not exist (1305).");
		}
		Hashtable hashtable = (Hashtable) parameters.get(name);
		if (hashtable == null) {
			return null;
		}
		String as[] = new String[hashtable.size()];
		for (int i = 0; i < hashtable.size(); i++) {
			as[i] = (String) hashtable.get(new Integer(i));
		}
		return as;
	}
}