httpservlet.java

程序切片原型系统

     * @param req	the {@link HttpServletRequest} object that
     *			contains the request the client made of
     *			the servlet
     *
     *
     * @param resp	the {@link HttpServletResponse} object that
     *			contains the response the servlet returns
     *			to the client				
     *
     *
     * @exception IOException	if an input or output error occurs
     *				while the servlet is handling the
     *				TRACE request
     *
     * @exception ServletException	if the request for the
     *					TRACE cannot be handled
     * 
     * @see 				javax.servlet.Servlet#service
     *
     */

    protected void service(HttpServletRequest req, HttpServletResponse resp)
	throws ServletException, IOException
    {
	String method = req.getMethod();

	if (method.equals(METHOD_GET)) {
	    long lastModified = getLastModified(req);
	    if (lastModified == -1) {
		// servlet doesn't support if-modified-since, no reason
		// to go through further expensive logic
		doGet(req, resp);
	    } else {
		long ifModifiedSince = req.getDateHeader(HEADER_IFMODSINCE);
		if (ifModifiedSince < (lastModified / 1000 * 1000)) {
		    // If the servlet mod time is later, call doGet()
                    // Round down to the nearest second for a proper compare
                    // A ifModifiedSince of -1 will always be less
		    maybeSetLastModified(resp, lastModified);
		    doGet(req, resp);
		} else {
		    resp.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
		}
	    }

	} else if (method.equals(METHOD_HEAD)) {
	    long lastModified = getLastModified(req);
	    maybeSetLastModified(resp, lastModified);
	    doHead(req, resp);

	} else if (method.equals(METHOD_POST)) {
	    doPost(req, resp);
	    
	} else if (method.equals(METHOD_PUT)) {
	    doPut(req, resp);	
	    
	} else if (method.equals(METHOD_DELETE)) {
	    doDelete(req, resp);
	    
	} else if (method.equals(METHOD_OPTIONS)) {
	    doOptions(req,resp);
	    
	} else if (method.equals(METHOD_TRACE)) {
	    doTrace(req,resp);
	    
	} else {
	    //
	    // Note that this means NO servlet supports whatever
	    // method was requested, anywhere on this server.
	    //

	    String errMsg = lStrings.getString("http.method_not_implemented");
	    Object[] errArgs = new Object[1];
	    errArgs[0] = method;
	    errMsg = MessageFormat.format(errMsg, errArgs);
	    
	    resp.sendError(HttpServletResponse.SC_NOT_IMPLEMENTED, errMsg);
	}
    }
    




    /*
     * Sets the Last-Modified entity header field, if it has not
     * already been set and if the value is meaningful.  Called before
     * doGet, to ensure that headers are set before response data is
     * written.  A subclass might have set this header already, so we
     * check.
     */

    private void maybeSetLastModified(HttpServletResponse resp,
				      long lastModified) {
	if (resp.containsHeader(HEADER_LASTMOD))
	    return;
	if (lastModified >= 0)
	    resp.setDateHeader(HEADER_LASTMOD, lastModified);
    }
   
   
   
    
    /**
     *
     * Dispatches client requests to the protected
     * <code>service</code> method. There's no need to
     * override this method.
     *
     * 
     * @param req	the {@link HttpServletRequest} object that
     *			contains the request the client made of
     *			the servlet
     *
     *
     * @param resp	the {@link HttpServletResponse} object that
     *			contains the response the servlet returns
     *			to the client				
     *
     *
     * @exception IOException	if an input or output error occurs
     *				while the servlet is handling the
     *				TRACE request
     *
     * @exception ServletException	if the request for the
     *					TRACE cannot be handled
     *
     * 
     * @see javax.servlet.Servlet#service
     *
     */

    public void service(ServletRequest req, ServletResponse res)
	throws ServletException, IOException
    {
	HttpServletRequest	request;
	HttpServletResponse	response;
	
	try {
	    request = (HttpServletRequest) req;
	    response = (HttpServletResponse) res;
	} catch (ClassCastException e) {
	    throw new ServletException("non-HTTP request or response");
	}
	service(request, response);
    }
}




/*
 * A response that includes no body, for use in (dumb) "HEAD" support.
 * This just swallows that body, counting the bytes in order to set
 * the content length appropriately.  All other methods delegate directly
 * to the HTTP Servlet Response object used to construct this one.
 */
// file private
class NoBodyResponse implements HttpServletResponse {
    private HttpServletResponse		resp;
    private NoBodyOutputStream		noBody;
    private PrintWriter			writer;
    private boolean			didSetContentLength;

    // file private
    NoBodyResponse(HttpServletResponse r) {
	resp = r;
	noBody = new NoBodyOutputStream();
    }

    // file private
    void setContentLength() {
	if (!didSetContentLength)
	  resp.setContentLength(noBody.getContentLength());
    }


    // SERVLET RESPONSE interface methods

    public void setContentLength(int len) {
	resp.setContentLength(len);
	didSetContentLength = true;
    }

    public void setContentType(String type)
      { resp.setContentType(type); }

    public ServletOutputStream getOutputStream() throws IOException
      { return noBody; }

    public String getCharacterEncoding()
	{ return resp.getCharacterEncoding(); }

    public PrintWriter getWriter() throws UnsupportedEncodingException
    {
	if (writer == null) {
	    OutputStreamWriter	w;

	    w = new OutputStreamWriter(noBody, getCharacterEncoding());
	    writer = new PrintWriter(w);
	}
	return writer;
    }

    public void setBufferSize(int size) throws IllegalStateException
      { resp.setBufferSize(size); }

    public int getBufferSize()
      { return resp.getBufferSize(); }

    public void reset() throws IllegalStateException
      { resp.reset(); }

    public boolean isCommitted()
      { return resp.isCommitted(); }

    public void flushBuffer() throws IOException
      { resp.flushBuffer(); }

    public void setLocale(Locale loc)
      { resp.setLocale(loc); }

    public Locale getLocale()
      { return resp.getLocale(); }


    // HTTP SERVLET RESPONSE interface methods

    public void addCookie(Cookie cookie)
      { resp.addCookie(cookie); }

    public boolean containsHeader(String name)
      { return resp.containsHeader(name); }

    /** @deprecated */
    public void setStatus(int sc, String sm)
      { resp.setStatus(sc, sm); }

    public void setStatus(int sc)
      { resp.setStatus(sc); }

    public void setHeader(String name, String value)
      { resp.setHeader(name, value); }

    public void setIntHeader(String name, int value)
      { resp.setIntHeader(name, value); }

    public void setDateHeader(String name, long date)
      { resp.setDateHeader(name, date); }

    public void sendError(int sc, String msg) throws IOException
      { resp.sendError(sc, msg); }

    public void sendError(int sc) throws IOException
      { resp.sendError(sc); }

    public void sendRedirect(String location) throws IOException
      { resp.sendRedirect(location); }
    
    public String encodeURL(String url) 
      { return resp.encodeURL(url); }

    public String encodeRedirectURL(String url)
      { return resp.encodeRedirectURL(url); }
      
    public void addHeader(String name, String value)
      { resp.addHeader(name, value); }
      
    public void addDateHeader(String name, long value)
      { resp.addDateHeader(name, value); }
      
    public void addIntHeader(String name, int value)
      { resp.addIntHeader(name, value); }
      
      
      

    /**
     * @deprecated	As of Version 2.1, replaced by
     * 			{@link HttpServletResponse#encodeURL}.
     *
     */
     
     
    public String encodeUrl(String url) 
      { return this.encodeURL(url); }
      
      
      
      
      
      
      

    /**
     * @deprecated	As of Version 2.1, replaced by
     *			{@link HttpServletResponse#encodeRedirectURL}.
     *
     */
     
     
    public String encodeRedirectUrl(String url)
      { return this.encodeRedirectURL(url); }

}







/*
 * Servlet output stream that gobbles up all its data.
 */
 
// file private
class NoBodyOutputStream extends ServletOutputStream {

    private static final String LSTRING_FILE =
	"javax.servlet.http.LocalStrings";
    private static ResourceBundle lStrings =
	ResourceBundle.getBundle(LSTRING_FILE);

    private int		contentLength = 0;

    // file private
    NoBodyOutputStream() {}

    // file private
    int getContentLength() {
	return contentLength;
    }

    public void write(int b) {
	contentLength++;
    }

    public void write(byte buf[], int offset, int len)
	throws IOException
    {
	if (len >= 0) {
	    contentLength += len;
	} else {
	    // XXX
	    // isn't this really an IllegalArgumentException?
	    
	    String msg = lStrings.getString("err.io.negativelength");
	    throw new IOException("negative length");
	}
    }
}