servletcontext.html

j2ee的API 1.4版本,j2ee的帮助文档

<PRE>
public <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/net/URL.html" title="class or interface in java.net">URL</A> <B>getResource</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;path)
                throws <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/net/MalformedURLException.html" title="class or interface in java.net">MalformedURLException</A></PRE>
<DL>
<DD>Returns a URL to the resource that is mapped to a specified
 path. The path must begin with a "/" and is interpreted
 as relative to the current context root.

 <p>This method allows the servlet container to make a resource 
 available to servlets from any source. Resources 
 can be located on a local or remote
 file system, in a database, or in a <code>.war</code> file. 

 <p>The servlet container must implement the URL handlers
 and <code>URLConnection</code> objects that are necessary
 to access the resource.

 <p>This method returns <code>null</code>
 if no resource is mapped to the pathname.

 <p>Some containers may allow writing to the URL returned by
 this method using the methods of the URL class.

 <p>The resource content is returned directly, so be aware that 
 requesting a <code>.jsp</code> page returns the JSP source code.
 Use a <code>RequestDispatcher</code> instead to include results of 
 an execution.

 <p>This method has a different purpose than
 <code>java.lang.Class.getResource</code>,
 which looks up resources based on a class loader. This
 method does not use class loaders.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>path</CODE> - a <code>String</code> specifying
						the path to the resource
<DT><B>Returns:</B><DD>the resource located at the named path,
 						or <code>null</code> if there is no resource
						at that path
<DT><B>Throws:</B>
<DD><CODE><A HREF="http://java.sun.com/j2se/1.4/docs/api/java/net/MalformedURLException.html" title="class or interface in java.net">MalformedURLException</A></CODE> - if the pathname is not given in 
 						the correct form</DL>
</DD>
</DL>
<HR>

<A NAME="getResourceAsStream(java.lang.String)"><!-- --></A><H3>
getResourceAsStream</H3>
<PRE>
public <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/io/InputStream.html" title="class or interface in java.io">InputStream</A> <B>getResourceAsStream</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;path)</PRE>
<DL>
<DD>Returns the resource located at the named path as
 an <code>InputStream</code> object.

 <p>The data in the <code>InputStream</code> can be 
 of any type or length. The path must be specified according
 to the rules given in <code>getResource</code>.
 This method returns <code>null</code> if no resource exists at
 the specified path. 
 
 <p>Meta-information such as content length and content type
 that is available via <code>getResource</code>
 method is lost when using this method.

 <p>The servlet container must implement the URL handlers
 and <code>URLConnection</code> objects necessary to access
 the resource.

 <p>This method is different from 
 <code>java.lang.Class.getResourceAsStream</code>,
 which uses a class loader. This method allows servlet containers 
 to make a resource available
 to a servlet from any location, without using a class loader.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>path</CODE> - a <code>String</code> specifying the path
			to the resource
<DT><B>Returns:</B><DD>the <code>InputStream</code> returned to the 
			servlet, or <code>null</code> if no resource
			exists at the specified path</DL>
</DD>
</DL>
<HR>

<A NAME="getRequestDispatcher(java.lang.String)"><!-- --></A><H3>
getRequestDispatcher</H3>
<PRE>
public <A HREF="../../javax/servlet/RequestDispatcher.html" title="interface in javax.servlet">RequestDispatcher</A> <B>getRequestDispatcher</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;path)</PRE>
<DL>
<DD>Returns a <A HREF="../../javax/servlet/RequestDispatcher.html" title="interface in javax.servlet"><CODE>RequestDispatcher</CODE></A> object that acts
 as a wrapper for the resource located at the given path.
 A <code>RequestDispatcher</code> object can be used to forward 
 a request to the resource or to include the resource in a response.
 The resource can be dynamic or static.

 <p>The pathname must begin with a "/" and is interpreted as relative
 to the current context root.  Use <code>getContext</code> to obtain
 a <code>RequestDispatcher</code> for resources in foreign contexts.
 This method returns <code>null</code> if the <code>ServletContext</code>
 cannot return a <code>RequestDispatcher</code>.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>path</CODE> - a <code>String</code> specifying the pathname
			to the resource
<DT><B>Returns:</B><DD>a <code>RequestDispatcher</code> object
			that acts as a wrapper for the resource
			at the specified path, or <code>null</code> if 
			the <code>ServletContext</code> cannot return
			a <code>RequestDispatcher</code><DT><B>See Also:</B><DD><A HREF="../../javax/servlet/RequestDispatcher.html" title="interface in javax.servlet"><CODE>RequestDispatcher</CODE></A>, 
<A HREF="../../javax/servlet/ServletContext.html#getContext(java.lang.String)"><CODE>getContext(java.lang.String)</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="getNamedDispatcher(java.lang.String)"><!-- --></A><H3>
getNamedDispatcher</H3>
<PRE>
public <A HREF="../../javax/servlet/RequestDispatcher.html" title="interface in javax.servlet">RequestDispatcher</A> <B>getNamedDispatcher</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;name)</PRE>
<DL>
<DD>Returns a <A HREF="../../javax/servlet/RequestDispatcher.html" title="interface in javax.servlet"><CODE>RequestDispatcher</CODE></A> object that acts
 as a wrapper for the named servlet.

 <p>Servlets (and JSP pages also) may be given names via server 
 administration or via a web application deployment descriptor.
 A servlet instance can determine its name using 
 <A HREF="../../javax/servlet/ServletConfig.html#getServletName()"><CODE>ServletConfig.getServletName()</CODE></A>.

 <p>This method returns <code>null</code> if the 
 <code>ServletContext</code>
 cannot return a <code>RequestDispatcher</code> for any reason.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>name</CODE> - a <code>String</code> specifying the name
			of a servlet to wrap
<DT><B>Returns:</B><DD>a <code>RequestDispatcher</code> object
			that acts as a wrapper for the named servlet,
			or <code>null</code> if the <code>ServletContext</code>
			cannot return a <code>RequestDispatcher</code><DT><B>See Also:</B><DD><A HREF="../../javax/servlet/RequestDispatcher.html" title="interface in javax.servlet"><CODE>RequestDispatcher</CODE></A>, 
<A HREF="../../javax/servlet/ServletContext.html#getContext(java.lang.String)"><CODE>getContext(java.lang.String)</CODE></A>, 
<A HREF="../../javax/servlet/ServletConfig.html#getServletName()"><CODE>ServletConfig.getServletName()</CODE></A></DL>
</DD>
</DL>
<HR>

<A NAME="getServlet(java.lang.String)"><!-- --></A><H3>
getServlet</H3>
<PRE>
public <A HREF="../../javax/servlet/Servlet.html" title="interface in javax.servlet">Servlet</A> <B>getServlet</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;name)
                   throws <A HREF="../../javax/servlet/ServletException.html" title="class in javax.servlet">ServletException</A></PRE>
<DL>
<DD><B>Deprecated.</B>&nbsp;<I>As of Java Servlet API 2.1, with no direct replacement.

 <p>This method was originally defined to retrieve a servlet
 from a <code>ServletContext</code>. In this version, this method 
 always returns <code>null</code> and remains only to preserve 
 binary compatibility. This method will be permanently removed 
 in a future version of the Java Servlet API.

 <p>In lieu of this method, servlets can share information using the 
 <code>ServletContext</code> class and can perform shared business logic
 by invoking methods on common non-servlet classes.</I>
<P>
<DD><DL>

<DT><B>Throws:</B>
<DD><CODE><A HREF="../../javax/servlet/ServletException.html" title="class in javax.servlet">ServletException</A></CODE></DL>
</DD>
</DL>
<HR>

<A NAME="getServlets()"><!-- --></A><H3>
getServlets</H3>
<PRE>
public <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/util/Enumeration.html" title="class or interface in java.util">Enumeration</A> <B>getServlets</B>()</PRE>
<DL>
<DD><B>Deprecated.</B>&nbsp;<I>As of Java Servlet API 2.0, with no replacement.

 <p>This method was originally defined to return an <code>Enumeration</code>
 of all the servlets known to this servlet context. In this
 version, this method always returns an empty enumeration and
 remains only to preserve binary compatibility. This method
 will be permanently removed in a future version of the Java
 Servlet API.</I>
<P>
<DD><DL>
</DL>
</DD>
</DL>
<HR>

<A NAME="getServletNames()"><!-- --></A><H3>
getServletNames</H3>
<PRE>
public <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/util/Enumeration.html" title="class or interface in java.util">Enumeration</A> <B>getServletNames</B>()</PRE>
<DL>
<DD><B>Deprecated.</B>&nbsp;<I>As of Java Servlet API 2.1, with no replacement.

 <p>This method was originally defined to return an 
 <code>Enumeration</code>
 of all the servlet names known to this context. In this version,
 this method always returns an empty <code>Enumeration</code> and 
 remains only to preserve binary compatibility. This method will 
 be permanently removed in a future version of the Java Servlet API.</I>
<P>
<DD><DL>
</DL>
</DD>
</DL>
<HR>

<A NAME="log(java.lang.String)"><!-- --></A><H3>
log</H3>
<PRE>
public void <B>log</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;msg)</PRE>
<DL>
<DD>Writes the specified message to a servlet log file, usually
 an event log. The name and type of the servlet log file is 
 specific to the servlet container.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>msg</CODE> - a <code>String</code> specifying the 
			message to be written to the log file</DL>
</DD>
</DL>
<HR>

<A NAME="log(java.lang.Exception, java.lang.String)"><!-- --></A><H3>
log</H3>
<PRE>
public void <B>log</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Exception.html" title="class or interface in java.lang">Exception</A>&nbsp;exception,
                <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;msg)</PRE>
<DL>
<DD><B>Deprecated.</B>&nbsp;<I>As of Java Servlet API 2.1, use
 			<A HREF="../../javax/servlet/ServletContext.html#log(java.lang.String, java.lang.Throwable)"><CODE>log(String message, Throwable throwable)</CODE></A> 
			instead.

 <p>This method was originally defined to write an 
 exception's stack trace and an explanatory error message
 to the servlet log file.</I>
<P>
<DD><DL>
</DL>
</DD>
</DL>
<HR>

<A NAME="log(java.lang.String, java.lang.Throwable)"><!-- --></A><H3>
log</H3>
<PRE>
public void <B>log</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;message,
                <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/Throwable.html" title="class or interface in java.lang">Throwable</A>&nbsp;throwable)</PRE>
<DL>
<DD>Writes an explanatory message and a stack trace
 for a given <code>Throwable</code> exception
 to the servlet log file. The name and type of the servlet log 
 file is specific to the servlet container, usually an event log.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>message</CODE> - a <code>String</code> that 
				describes the error or exception<DD><CODE>throwable</CODE> - the <code>Throwable</code> error 
				or exception</DL>
</DD>
</DL>
<HR>

<A NAME="getRealPath(java.lang.String)"><!-- --></A><H3>
getRealPath</H3>
<PRE>
public <A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A> <B>getRealPath</B>(<A HREF="http://java.sun.com/j2se/1.4/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A>&nbsp;path)</PRE>