servletrequest.java

windows下的JAVA虚拟机

/*
* Copyright 2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package javax.servlet;

import java.io.BufferedReader;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Locale;
import java.util.Map;



/**
 * Defines an object to provide client request information to a servlet.  The
 * servlet container creates a <code>ServletRequest</code> object and passes
 * it as an argument to the servlet's <code>service</code> method.
 *
 * <p>A <code>ServletRequest</code> object provides data including
 * parameter name and values, attributes, and an input stream.
 * Interfaces that extend <code>ServletRequest</code> can provide
 * additional protocol-specific data (for example, HTTP data is
 * provided by {@link javax.servlet.http.HttpServletRequest}.
 * 
 * @author 	Various
 * @version 	$Version$
 *
 * @see 	javax.servlet.http.HttpServletRequest
 *
 */

public interface ServletRequest {




    /**
     *
     * Returns the value of the named attribute as an <code>Object</code>,
     * or <code>null</code> if no attribute of the given name exists. 
     *
     * <p> Attributes can be set two ways.  The servlet container may set
     * attributes to make available custom information about a request.
     * For example, for requests made using HTTPS, the attribute
     * <code>javax.servlet.request.X509Certificate</code> can be used to
     * retrieve information on the certificate of the client.  Attributes
     * can also be set programatically using 
     * {@link ServletRequest#setAttribute}.  This allows information to be
     * embedded into a request before a {@link RequestDispatcher} call.
     *
     * <p>Attribute names should follow the same conventions as package
     * names. This specification reserves names matching <code>java.*</code>,
     * <code>javax.*</code>, and <code>sun.*</code>. 
     *
     * @param name	a <code>String</code> specifying the name of 
     *			the attribute
     *
     * @return		an <code>Object</code> containing the value 
     *			of the attribute, or <code>null</code> if
     *			the attribute does not exist
     *
     */

    public Object getAttribute(String name);
    
    

    /**
     * Returns an <code>Enumeration</code> containing the
     * names of the attributes available to this request. 
     * This method returns an empty <code>Enumeration</code>
     * if the request has no attributes available to it.
     * 
     *
     * @return		an <code>Enumeration</code> of strings 
     *			containing the names 
     * 			of the request's attributes
     *
     */

    public Enumeration getAttributeNames();
    
    
    
    
    /**
     * Returns the name of the character encoding used in the body of this
     * request. This method returns <code>null</code> if the request
     * does not specify a character encoding
     * 
     *
     * @return		a <code>String</code> containing the name of 
     *			the character encoding, or <code>null</code>
     *			if the request does not specify a character encoding
     *
     */

    public String getCharacterEncoding();

 /**
     * Overrides the name of the character encoding used in the body of this
     * request. This method must be called prior to reading request parameters
     * or reading input using getReader().
     * 
     *
     * @param env	a <code>String</code> containing the name of 
     *			the character encoding.
     * @throws		java.io.UnsupportedEncodingException if this is not a valid encoding
     */

    public void setCharacterEncoding(String env) throws java.io.UnsupportedEncodingException;

    
    
    
    
    /**
     * Returns the length, in bytes, of the request body 
     * and made available by the input stream, or -1 if the
     * length is not known. For HTTP servlets, same as the value
     * of the CGI variable CONTENT_LENGTH.
     *
     * @return		an integer containing the length of the 
     * 			request body or -1 if the length is not known
     *
     */

    public int getContentLength();
    
    
    

    /**
     * Returns the MIME type of the body of the request, or 
     * <code>null</code> if the type is not known. For HTTP servlets, 
     * same as the value of the CGI variable CONTENT_TYPE.
     *
     * @return		a <code>String</code> containing the name 
     *			of the MIME type of 
     * 			the request, or null if the type is not known
     *
     */

    public String getContentType();
    
    
    

    /**
     * Retrieves the body of the request as binary data using
     * a {@link ServletInputStream}.  Either this method or 
     * {@link #getReader} may be called to read the body, not both.
     *
     * @return			a {@link ServletInputStream} object containing
     * 				the body of the request
     *
     * @exception IllegalStateException  if the {@link #getReader} method
     * 					 has already been called for this request
     *
     * @exception IOException    	if an input or output exception occurred
     *
     */

    public ServletInputStream getInputStream() throws IOException; 
     
    
    

    /**
     * Returns the value of a request parameter as a <code>String</code>,
     * or <code>null</code> if the parameter does not exist. Request parameters
     * are extra information sent with the request.  For HTTP servlets,
     * parameters are contained in the query string or posted form data.
     *
     * <p>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 {@link #getParameterValues}.
     *
     * <p>If you use this method with a multivalued
     * parameter, the value returned is equal to the first value
     * in the array returned by <code>getParameterValues</code>.
     *
     * <p>If the parameter data was sent in the request body, such as occurs
     * with an HTTP POST request, then reading the body directly via {@link
     * #getInputStream} or {@link #getReader} can interfere
     * with the execution of this method.
     *
     * @param name 	a <code>String</code> specifying the 
     *			name of the parameter
     *
     * @return		a <code>String</code> representing the 
     *			single value of the parameter
     *
     * @see 		#getParameterValues
     *
     */

    public String getParameter(String name);
    
    
    

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

    /**
     * Returns an array of <code>String</code> objects containing 
     * all of the values the given request parameter has, or 
     * <code>null</code> if the parameter does not exist.
     *
     * <p>If the parameter has a single value, the array has a length
     * of 1.
     *
     * @param name	a <code>String</code> containing the name of 
     *			the parameter whose value is requested
     *
     * @return		an array of <code>String</code> objects 
     *			containing the parameter's values
     *
     * @see		#getParameter
     *
     */

    public String[] getParameterValues(String name);
 
    /** Returns a java.util.Map of the parameters of this request.
     * Request parameters
     * are extra information sent with the request.  For HTTP servlets,
     * parameters are contained in the query string or posted form data.
     *
     * @return an immutable java.util.Map containing parameter names as 
     * keys and parameter values as map values. The keys in the parameter
     * map are of type String. The values in the parameter map are of type
     * String array.
     *
     */

    public Map getParameterMap();
    
    

    /**
     * Returns the name and version of the protocol the request uses
     * in the form <i>protocol/majorVersion.minorVersion</i>, for 
     * example, HTTP/1.1. For HTTP servlets, the value
     * returned is the same as the value of the CGI variable 
     * <code>SERVER_PROTOCOL</code>.
     *
     * @return		a <code>String</code> containing the protocol 
     *			name and version number
     *
     */
    
    public String getProtocol();
    
    
    

    /**
     * Returns the name of the scheme used to make this request, 
     * for example,
     * <code>http</code>, <code>https</code>, or <code>ftp</code>.
     * Different schemes have different rules for constructing URLs,
     * as noted in RFC 1738.
     *
     * @return		a <code>String</code> containing the name 
     *			of the scheme used to make this request
     *
     */