statenavigationhashfilter.java

ajax patterns 这是关于ajax设计模式方面的原代码

/*
    Copyright 2006 Christian Gross http://www.devspace.com
    From the book Ajax Patterns and Best Practices

   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 devspace.ajax.statenavigation;
import javax.servlet.http.*;
import devspace.testDrivenDevelopment.tracer.*;
import javax.servlet.*;
import java.io.*;

public class StateNavigationHashFilter extends NavigationBase< StateNavigationHashData> {
    public StateNavigationHashData initializeRequest() {
        return new StateNavigationHashData();
    }
    public void destroyRequest( StateNavigationHashData objData) {
        
    }
    
    public boolean isTrigger( StateNavigationHashData data, HttpServletRequest httprequest, HttpServletResponse httpresponse) {
        if( httprequest.getRequestURI().length() <= _URLStateIdentifierLength) {
            return false;
        }
        String tail = httprequest.getRequestURI().substring(
            httprequest.getRequestURI().length() - _URLStateIdentifierLength);
        GenerateOutput.Write( "StateNavigationFilter.IsTrigger", "Checking if path (" + httprequest.getRequestURI() +
                             ") ending (" + tail + ") has (" + _URLStateIdentifier + ")");
        String stateHeader = httprequest.getHeader( _XPageState);
        GenerateOutput.Write( "StateNavigationFilter.IsTrigger", "Getting the Page State Identifier eg #10->10 (" + stateHeader + ")");
        
        if (tail.compareTo(_URLStateIdentifier) == 0) {
            data._path = httprequest.getRequestURI().substring( 0,
                                                               httprequest.getRequestURI().length() - _URLStateIdentifierLength);
        }
        else {
            if (stateHeader == null) {
                return false;
            }
            data._path = httprequest.getRequestURI();
        }
        
        data._method = httprequest.getMethod();
        data._stateHeader = stateHeader;
        data._operation = StateNavigationHashData.OP_NONE;
        GenerateOutput.Write( "StateNavigationFilter.IsTrigger", "data.ToString (" + data.toString() + ")");
        if (data._method.compareTo("GET") == 0) {
            GenerateOutput.Write( "StateNavigationFilter.IsTrigger", "This is a retrieval HTTP GET");
            data._operation = StateNavigationHashData.OP_RETRIEVE;
            return true;
        }
        else if (data._method.compareTo("PUT") == 0 || data._method.compareTo("POST") == 0) {
            GenerateOutput.Write( "StateNavigationFilter.IsTrigger", "This is a retrieval HTTP POST");
            data._operation = StateNavigationHashData.OP_POST;
            return true;
        }
        data.reset();
        return false;
    }
    public void runFilter( StateNavigationHashData data, HttpServletRequest httprequest, HttpServletResponse httpresponse, FilterChain chain) throws IOException, ServletException  {
        GenerateOutput.Write( "StateNavigationFilter.RunFilter", "Running the filter");
        if (data._operation == StateNavigationHashData.OP_RETRIEVE) {
            GenerateOutput.Write( "StateNavigationFilter.RunFilter", "Doing a retrieval");
            State state;
            if (data._stateHeader == null || data._stateHeader.compareTo("none") == 0) {
                GenerateOutput.Write( "StateNavigationFilter.RunFilter", "There is no state so get an empty state");
                state = _stateManager.getEmptyState();
            }
            else {
                GenerateOutput.Write( "StateNavigationFilter.RunFilter", "There is a state so retrieve it from the state manager");
                state = _stateManager.copyState(data._stateHeader);
            }
            httpresponse.setContentType( _resourceStateContentType);
            httpresponse.setHeader( _XPageState, state.getStateIdentifier());
            httpresponse.setStatus( 200, "success");
            PrintWriter out = httpresponse.getWriter();
            out.print( state.getBuffer());
            return;
        }
        else if (data._operation == StateNavigationHashData.OP_POST) {
            GenerateOutput.Write( "StateNavigationFilter.RunFilter", "Doing a posting");
            ServletInputStream input = httprequest.getInputStream();
            byte[] bytearray = new byte[ httprequest.getContentLength()];
            input.read( bytearray);
            State state = _stateManager.getState(data._stateHeader);
            state.setURL( data._path);
            state.setBuffer( new String( bytearray).toString());
            GenerateOutput.Write( "StateNavigationFilter.RunFilter", "Save state buffer is (" + state.toString() + ")");
            httpresponse.addHeader( _XPageState, state.getStateIdentifier());
            httpresponse.setStatus( 200);
            chain.doFilter( httprequest, httpresponse);
            return;
        }
    }
    
    public void destroy() {
    }
    
}