dwrpplainjsmarshaller.java

Ajax 框架,可以用来做数型菜单或者联动下拉列表

/*
 * Copyright 2005 Joe Walker
 *
 * 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 org.directwebremoting.dwrp;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.directwebremoting.AccessControl;
import org.directwebremoting.Calls;
import org.directwebremoting.ConverterManager;
import org.directwebremoting.Creator;
import org.directwebremoting.CreatorManager;
import org.directwebremoting.InboundContext;
import org.directwebremoting.InboundVariable;
import org.directwebremoting.MarshallException;
import org.directwebremoting.Marshaller;
import org.directwebremoting.OutboundContext;
import org.directwebremoting.OutboundVariable;
import org.directwebremoting.Replies;
import org.directwebremoting.Reply;
import org.directwebremoting.ScriptSession;
import org.directwebremoting.TypeHintContext;
import org.directwebremoting.WebContext;
import org.directwebremoting.WebContextFactory;
import org.directwebremoting.util.DebuggingPrintWriter;
import org.directwebremoting.util.JavascriptUtil;
import org.directwebremoting.util.LocalUtil;
import org.directwebremoting.util.Logger;
import org.directwebremoting.util.Messages;
import org.directwebremoting.util.MimeConstants;

/**
 * A Marshaller that output plain Javascript.
 * This marshaller can be tweaked to output Javascript in an HTML context.
 * This class works in concert with DirectScriptConduit, they should be
 * considered closely related and it is important to understand what one does
 * while editing the other.
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class DwrpPlainJsMarshaller implements Marshaller
{
    /* (non-Javadoc)
     * @see org.directwebremoting.Marshaller#marshallInbound(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    public Calls marshallInbound(HttpServletRequest request, HttpServletResponse response) throws IOException
    {
        // We must parse the parameters before we setup the conduit because it's
        // only after doing this that we know the scriptSessionId
        CallsWithContext calls = parseRequest(request);

        // Get the output stream and setup the mimetype
        response.setContentType(getOutboundMimeType());
        PrintWriter out;
        if (log.isDebugEnabled())
        {
            // This might be considered evil - altering the program flow
            // depending on the log status, however DebuggingPrintWriter is
            // very thin and only about logging
            out = new DebuggingPrintWriter("", response.getWriter()); //$NON-NLS-1$
        }
        else
        {
            out = response.getWriter();
        }

        // Save the output stream so the outbound marshaller can get at it
        request.setAttribute(ATTRIBUTE_REQUEST, out);

        // The conduit to pass on reverse ajax scripts
        DirectScriptConduit conduit = new DirectScriptConduit(out, response, this);
        request.setAttribute(ATTRIBUTE_CONDUIT, conduit);

        // Setup a debugging prefix
        if (out instanceof DebuggingPrintWriter)
        {
            DebuggingPrintWriter dpw = (DebuggingPrintWriter) out;
            dpw.setPrefix("out(" + conduit.hashCode() + "): "); //$NON-NLS-1$ //$NON-NLS-2$
        }

        // Send the script prefix (if any)
        sendOutboundScriptPrefix(out, response);
        out.flush();
        response.flushBuffer();

        // From the call to addScriptConduit() there could be 2 threads writing
        // to 'out' so we synchronize on 'out' to make sure there are no
        // clashes
        ScriptSession scriptSession = WebContextFactory.get().getScriptSession();
        scriptSession.addScriptConduit(conduit);

        // Debug the environment
        if (log.isDebugEnabled() && calls.getCallCount() > 0)
        {
            // We can just use 0 because they are all shared
            InboundContext inctx = calls.getCallWithContext(0).getInboundContext();
            StringBuffer buffer = new StringBuffer();

            for (Iterator it = inctx.getInboundVariableNames(); it.hasNext();)
            {
                String key = (String) it.next();
                InboundVariable value = inctx.getInboundVariable(key);
                if (key.startsWith(ConversionConstants.INBOUND_CALLNUM_PREFIX) &&
                    key.indexOf(ConversionConstants.INBOUND_CALLNUM_SUFFIX + ConversionConstants.INBOUND_KEY_ENV) != -1)
                {
                    buffer.append(key + '=' + value.toString() + ", "); //$NON-NLS-1$
                }
            }

            if (buffer.length() > 0)
            {
                log.debug("Environment:  " + buffer.toString()); //$NON-NLS-1$
            }
        }

        callLoop:
        for (int callNum = 0; callNum < calls.getCallCount(); callNum++)
        {
            CallWithContext call = calls.getCallWithContext(callNum);
            InboundContext inctx = call.getInboundContext();


            // Get a list of the available matching methods with the coerced
            // parameters that we will use to call it if we choose to use
            // that method.
            Creator creator = creatorManager.getCreator(call.getScriptName());

            // Which method are we using?
            Method method = findMethod(call);
            call.setMethod(method);
            if (method == null)
            {
                String name = call.getScriptName() + '.' + call.getMethodName();
                throw new IllegalArgumentException(Messages.getString("DefaultRemoter.UnknownMethod", name)); //$NON-NLS-1$
            }

            // Check this method is accessible
            String reason = accessControl.getReasonToNotExecute(creator, call.getScriptName(), method);
            if (reason != null)
            {
                throw new SecurityException(Messages.getString("ExecuteQuery.AccessDenied")); //$NON-NLS-1$
            }

            // Convert all the parameters to the correct types
            Object[] params = new Object[method.getParameterTypes().length];
            for (int j = 0; j < method.getParameterTypes().length; j++)
            {
                try
                {
                    Class paramType = method.getParameterTypes()[j];
                    InboundVariable param = inctx.getParameter(callNum, j);
                    TypeHintContext incc = new TypeHintContext(converterManager, method, j);
                    params[j] = converterManager.convertInbound(paramType, param, inctx, incc);
                }
                catch (MarshallException ex)
                {
                    log.debug("Marshalling exception: " + ex.getMessage()); //$NON-NLS-1$

                    call.setMethod(null);
                    call.setParameters(null);
                    call.setException(ex);

                    continue callLoop;
                }
            }

            call.setParameters(params);
        }

        return calls;
    }

    /**
     * Find the method the best matches the method name and parameters
     * @param call The function call we are going to make
     * @return A matching method, or null if one was not found.
     */
    private Method findMethod(CallWithContext call)
    {
        if (call.getScriptName() == null)
        {
            throw new IllegalArgumentException(Messages.getString("DefaultRemoter.MissingClassParam")); //$NON-NLS-1$
        }

        if (call.getMethodName() == null)
        {
            throw new IllegalArgumentException(Messages.getString("DefaultRemoter.MissingMethodParam")); //$NON-NLS-1$
        }

        Creator creator = creatorManager.getCreator(call.getScriptName());
        Method[] methods = creator.getType().getMethods();
        List available = new ArrayList();

        methods:
        for (int i = 0; i < methods.length; i++)
        {
            // Check method name and access
            if (methods[i].getName().equals(call.getMethodName()))
            {
                // Check number of parameters
                if (methods[i].getParameterTypes().length == call.getInboundContext().getParameterCount())
                {
                    // Clear the previous conversion attempts (the param types
                    // will probably be different)
                    call.getInboundContext().clearConverted();

                    // Check parameter types
                    for (int j = 0; j < methods[i].getParameterTypes().length; j++)
                    {
                        Class paramType = methods[i].getParameterTypes()[j];
                        if (!converterManager.isConvertable(paramType))
                        {
                            // Give up with this method and try the next
                            continue methods;
                        }
                    }

                    available.add(methods[i]);
                }
            }
        }

        // Pick a method to call
        if (available.size() > 1)
        {
            log.warn("Warning multiple matching methods. Using first match."); //$NON-NLS-1$
        }

        if (available.isEmpty())
        {
            String name = call.getScriptName() + '.' + call.getMethodName();
            throw new IllegalArgumentException(Messages.getString("DefaultRemoter.UnknownMethod", name)); //$NON-NLS-1$
        }

        // At the moment we are just going to take the first match, for a
        // later increment we might pick the best implementation
        return (Method) available.get(0);
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.Marshaller#marshallOutbound(org.directwebremoting.Replies, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    public void marshallOutbound(Replies replies, HttpServletRequest request, HttpServletResponse response) throws IOException
    {
        // We build the answer up in a StringBuffer because that makes is easier
        // to debug, and because that's only what the compiler does anyway.
        PrintWriter out = (PrintWriter) request.getAttribute(ATTRIBUTE_REQUEST);
        DirectScriptConduit conduit = (DirectScriptConduit) request.getAttribute(ATTRIBUTE_CONDUIT);

        ScriptSession scriptSession = WebContextFactory.get().getScriptSession();

        OutboundContext converted = new OutboundContext();
        for (int i = 0; i < replies.getReplyCount(); i++)
        {
            Reply reply = replies.getReply(i);

            // The existance of a throwable indicates that something went wrong
            if (reply.getThrowable() != null)
            {
                Throwable ex = reply.getThrowable();
                OutboundVariable ov = convertException(ex, converted);

                String script = ov.getInitCode() + "DWREngine._handleServerError('" + reply.getId() + "', " + ov.getAssignCode() + ");"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
                sendScript(out, response, script);

                log.warn("--Erroring: id[" + reply.getId() + "] message[" + ex.toString() + ']'); //$NON-NLS-1$ //$NON-NLS-2$
            }
            else
            {
                Object data = reply.getReply();

                try
                {
                    OutboundVariable ov = converterManager.convertOutbound(data, converted);

                    String script = ov.getInitCode() + "DWREngine._handleResponse('" + reply.getId() + "', " + ov.getAssignCode() + ");"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
                    sendScript(out, response, script);
                }
                catch (MarshallException ex)
                {
                    OutboundVariable ov = convertException(ex, converted);

                    String script = ov.getInitCode() + "DWREngine._handleServerError('" + reply.getId() + "', " + ov.getAssignCode() + ");"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
                    sendScript(out, response, script);

                    log.warn("--Erroring: id[" + reply.getId() + "] message[" + ex.toString() + ']'); //$NON-NLS-1$ //$NON-NLS-2$
                }                
            }
        }

        scriptSession.removeScriptConduit(conduit);
        conduit.close();

        sendOutboundScriptSuffix(out, response);

        // log.debug(replyString);
    }

    /**
     * Send a script to the browser
     * @param out The stream to write to
     * @param response The http response so we can flush
     * @param script The script to send
     * @throws IOException If the write fails
     */
    protected void sendScript(PrintWriter out, HttpServletResponse response, String script) throws IOException
    {
        if (script.trim().length() == 0)
        {
            log.warn("Skipping empty script", new Exception()); //$NON-NLS-1$
            return;
        }

        synchronized (out)
        {
            out.println(ConversionConstants.SCRIPT_START_MARKER);
            out.println(script);
            out.println(ConversionConstants.SCRIPT_END_MARKER);

            out.flush();
            response.flushBuffer();
        }
    }

    /**
     * iframe mode starts as HTML, so get into script mode
     * @return A script prefix
     */
    protected String getOutboundMimeType()
    {
        return MimeConstants.MIME_PLAIN;
    }

    /**
     * iframe mode starts as HTML, so get into script mode
     * @param out The stream to write to