Tomcat example source code file (SSIProcessor.java)

This example Tomcat source code file (SSIProcessor.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Tomcat tags/keywords

command_end, command_start, hashmap, io, ssicommand, ssicommand, ssiconditional, ssiconditional, ssimediator, ssiprocessor, string, string, stringbuffer, stringbuffer, stringwriter, util

The Tomcat SSIProcessor.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.catalina.ssi;


import java.io.IOException;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.StringTokenizer;
import org.apache.catalina.util.IOTools;
/**
 * The entry point to SSI processing. This class does the actual parsing,
 * delegating to the SSIMediator, SSICommand, and SSIExternalResolver as
 * necessary[
 * 
 * @author Dan Sandberg
 * @author David Becker
 * @version $Revision: 531303 $, $Date: 2007-04-23 02:24:01 +0200 (lun., 23 avr. 2007) $
 */
public class SSIProcessor {
    /** The start pattern */
    protected final static String COMMAND_START = "<!--#";
    /** The end pattern */
    protected final static String COMMAND_END = "-->";
    protected final static int BUFFER_SIZE = 4096;
    protected SSIExternalResolver ssiExternalResolver;
    protected HashMap commands = new HashMap();
    protected int debug;


    public SSIProcessor(SSIExternalResolver ssiExternalResolver, int debug) {
        this.ssiExternalResolver = ssiExternalResolver;
        this.debug = debug;
        addBuiltinCommands();
    }


    protected void addBuiltinCommands() {
        addCommand("config", new SSIConfig());
        addCommand("echo", new SSIEcho());
        addCommand("exec", new SSIExec());
        addCommand("include", new SSIInclude());
        addCommand("flastmod", new SSIFlastmod());
        addCommand("fsize", new SSIFsize());
        addCommand("printenv", new SSIPrintenv());
        addCommand("set", new SSISet());
        SSIConditional ssiConditional = new SSIConditional();
        addCommand("if", ssiConditional);
        addCommand("elif", ssiConditional);
        addCommand("endif", ssiConditional);
        addCommand("else", ssiConditional);
    }


    public void addCommand(String name, SSICommand command) {
        commands.put(name, command);
    }


    /**
     * Process a file with server-side commands, reading from reader and
     * writing the processed version to writer. NOTE: We really should be doing
     * this in a streaming way rather than converting it to an array first.
     * 
     * @param reader
     *            the reader to read the file containing SSIs from
     * @param writer
     *            the writer to write the file with the SSIs processed.
     * @return the most current modified date resulting from any SSI commands
     * @throws IOException
     *             when things go horribly awry. Should be unlikely since the
     *             SSICommand usually catches 'normal' IOExceptions.
     */
    public long process(Reader reader, long lastModifiedDate,
            PrintWriter writer) throws IOException {
        SSIMediator ssiMediator = new SSIMediator(ssiExternalResolver,
                lastModifiedDate, debug);
        StringWriter stringWriter = new StringWriter();
        IOTools.flow(reader, stringWriter);
        String fileContents = stringWriter.toString();
        stringWriter = null;
        int index = 0;
        boolean inside = false;
        StringBuffer command = new StringBuffer();
        try {
            while (index < fileContents.length()) {
                char c = fileContents.charAt(index);
                if (!inside) {
                    if (c == COMMAND_START.charAt(0)
                            && charCmp(fileContents, index, COMMAND_START)) {
                        inside = true;
                        index += COMMAND_START.length();
                        command.setLength(0); //clear the command string
                    } else {
                        if (!ssiMediator.getConditionalState().processConditionalCommandsOnly) {
                            writer.write(c);
                        }
                        index++;
                    }
                } else {
                    if (c == COMMAND_END.charAt(0)
                            && charCmp(fileContents, index, COMMAND_END)) {
                        inside = false;
                        index += COMMAND_END.length();
                        String strCmd = parseCmd(command);
                        if (debug > 0) {
                            ssiExternalResolver.log(
                                    "SSIProcessor.process -- processing command: "
                                            + strCmd, null);
                        }
                        String[] paramNames = parseParamNames(command, strCmd
                                .length());
                        String[] paramValues = parseParamValues(command,
                                strCmd.length(), paramNames.length);
                        //We need to fetch this value each time, since it may
                        // change
                        // during the loop
                        String configErrMsg = ssiMediator.getConfigErrMsg();
                        SSICommand ssiCommand = (SSICommand)commands
                                .get(strCmd.toLowerCase());
                        String errorMessage = null;
                        if (ssiCommand == null) {
                            errorMessage = "Unknown command: " + strCmd;
                        } else if (paramValues == null) {
                            errorMessage = "Error parsing directive parameters.";
                        } else if (paramNames.length != paramValues.length) {
                            errorMessage = "Parameter names count does not match parameter values count on command: "
                                    + strCmd;
                        } else {
                            // don't process the command if we are processing
                            // conditional
                            // commands only and the
                            // command is not conditional
                            if (!ssiMediator.getConditionalState().processConditionalCommandsOnly
                                    || ssiCommand instanceof SSIConditional) {
                                long lmd = ssiCommand.process(ssiMediator, strCmd,
                                               paramNames, paramValues, writer);
                                if (lmd > lastModifiedDate) {
                                    lastModifiedDate = lmd;
                                }                                    
                            }
                        }
                        if (errorMessage != null) {
                            ssiExternalResolver.log(errorMessage, null);
                            writer.write(configErrMsg);
                        }
                    } else {
                        command.append(c);
                        index++;
                    }
                }
            }
        } catch (SSIStopProcessingException e) {
            //If we are here, then we have already stopped processing, so all
            // is good
        }
        return lastModifiedDate;
    }


    /**
     * Parse a StringBuffer and take out the param type token. Called from
     * <code>requestHandler
     * 
     * @param cmd
     *            a value of type 'StringBuffer'
     * @return a value of type 'String[]'
     */
    protected String[] parseParamNames(StringBuffer cmd, int start) {
        int bIdx = start;
        int i = 0;
        int quotes = 0;
        boolean inside = false;
        StringBuffer retBuf = new StringBuffer();
        while (bIdx < cmd.length()) {
            if (!inside) {
                while (bIdx < cmd.length() && isSpace(cmd.charAt(bIdx)))
                    bIdx++;
                if (bIdx >= cmd.length()) break;
                inside = !inside;
            } else {
                while (bIdx < cmd.length() && cmd.charAt(bIdx) != '=') {
                    retBuf.append(cmd.charAt(bIdx));
                    bIdx++;
                }
                retBuf.append('=');
                inside = !inside;
                quotes = 0;
                boolean escaped = false;
                for (; bIdx < cmd.length() && quotes != 2; bIdx++) {
                    char c = cmd.charAt(bIdx);
                    // Need to skip escaped characters
                    if (c == '\\' && !escaped) {
                        escaped = true;
                        bIdx++;
                        continue;
                    }
                    escaped = false;
                    if (c == '"') quotes++;
                }
            }
        }
        StringTokenizer str = new StringTokenizer(retBuf.toString(), "=");
        String[] retString = new String[str.countTokens()];
        while (str.hasMoreTokens()) {
            retString[i++] = str.nextToken().trim();
        }
        return retString;
    }


    /**
     * Parse a StringBuffer and take out the param token. Called from
     * <code>requestHandler
     * 
     * @param cmd
     *            a value of type 'StringBuffer'
     * @return a value of type 'String[]'
     */
    protected String[] parseParamValues(StringBuffer cmd, int start, int count) {
        int valIndex = 0;
        boolean inside = false;
        String[] vals = new String[count];
        StringBuffer sb = new StringBuffer();
        char endQuote = 0;
        for (int bIdx = start; bIdx < cmd.length(); bIdx++) {
            if (!inside) {
                while (bIdx < cmd.length() && !isQuote(cmd.charAt(bIdx)))
                    bIdx++;
                if (bIdx >= cmd.length()) break;
                inside = !inside;
                endQuote = cmd.charAt(bIdx);
            } else {
                boolean escaped = false;
                for (; bIdx < cmd.length(); bIdx++) {
                    char c = cmd.charAt(bIdx);
                    // Check for escapes
                    if (c == '\\' && !escaped) {
                        escaped = true;
                        continue;
                    }
                    // If we reach the other " then stop
                    if (c == endQuote && !escaped) break;
                    // Since parsing of attributes and var
                    // substitution is done in separate places,
                    // we need to leave escape in the string
                    if (c == '$' && escaped) sb.append('\\');
                    escaped = false;
                    sb.append(c);
                }
                // If we hit the end without seeing a quote
                // the signal an error
                if (bIdx == cmd.length()) return null;
                vals[valIndex++] = sb.toString();
                sb.delete(0, sb.length()); // clear the buffer
                inside = !inside;
            }
        }
        return vals;
    }


    /**
     * Parse a StringBuffer and take out the command token. Called from
     * <code>requestHandler
     * 
     * @param cmd
     *            a value of type 'StringBuffer'
     * @return a value of type 'String', or null if there is none
     */
    private String parseCmd(StringBuffer cmd) {
        int firstLetter = -1;
        int lastLetter = -1;
        for (int i = 0; i < cmd.length(); i++) {
            char c = cmd.charAt(i);
            if (Character.isLetter(c)) {
                if (firstLetter == -1) {
                    firstLetter = i;
                }
                lastLetter = i;
            } else if (isSpace(c)) {
                if (lastLetter > -1) {
                    break;
                }
            } else {
                break;
            }
        }
        String command = null;
        if (firstLetter != -1) {
            command = cmd.substring(firstLetter, lastLetter + 1);
        }
        return command;
    }


    protected boolean charCmp(String buf, int index, String command) {
        return buf.regionMatches(index, command, 0, command.length());
    }


    protected boolean isSpace(char c) {
        return c == ' ' || c == '\n' || c == '\t' || c == '\r';
    }
    
    protected boolean isQuote(char c) {
        return c == '\'' || c == '\"' || c == '`';
    }
}