Tomcat example source code file (ErrorDispatcher.java)

This example Tomcat source code file (ErrorDispatcher.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

errorvisitor, exception, io, ioexception, jasperexception, jasperexception, javacerrordetail, javacerrordetail, net, network, node, object, object, sax, saxexception, string, string, stringbuffer, util

The Tomcat ErrorDispatcher.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.jasper.compiler;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.StringReader;
import java.net.MalformedURLException;
import java.util.ArrayList;

import org.apache.jasper.JasperException;
import org.apache.jasper.JspCompilationContext;
import org.xml.sax.SAXException;

/**
 * Class responsible for dispatching JSP parse and javac compilation errors
 * to the configured error handler.
 *
 * This class is also responsible for localizing any error codes before they
 * are passed on to the configured error handler.
 * 
 * In the case of a Java compilation error, the compiler error message is
 * parsed into an array of JavacErrorDetail instances, which is passed on to 
 * the configured error handler.
 *
 * @author Jan Luehe
 * @author Kin-man Chung
 */
public class ErrorDispatcher {

    // Custom error handler
    private ErrorHandler errHandler;

    // Indicates whether the compilation was initiated by JspServlet or JspC
    private boolean jspcMode = false;


    /*
     * Constructor.
     *
     * @param jspcMode true if compilation has been initiated by JspC, false
     * otherwise
     */
    public ErrorDispatcher(boolean jspcMode) {
	// XXX check web.xml for custom error handler
	errHandler = new DefaultErrorHandler();
        this.jspcMode = jspcMode;
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param errCode Error code
     */
    public void jspError(String errCode) throws JasperException {
	dispatch(null, errCode, null, null);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param where Error location
     * @param errCode Error code
     */
    public void jspError(Mark where, String errCode) throws JasperException {
	dispatch(where, errCode, null, null);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param n Node that caused the error
     * @param errCode Error code
     */
    public void jspError(Node n, String errCode) throws JasperException {
	dispatch(n.getStart(), errCode, null, null);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param errCode Error code
     * @param arg Argument for parametric replacement
     */
    public void jspError(String errCode, String arg) throws JasperException {
	dispatch(null, errCode, new Object[] {arg}, null);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param where Error location
     * @param errCode Error code
     * @param arg Argument for parametric replacement
     */
    public void jspError(Mark where, String errCode, String arg)
	        throws JasperException {
	dispatch(where, errCode, new Object[] {arg}, null);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param n Node that caused the error
     * @param errCode Error code
     * @param arg Argument for parametric replacement
     */
    public void jspError(Node n, String errCode, String arg)
	        throws JasperException {
	dispatch(n.getStart(), errCode, new Object[] {arg}, null);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param errCode Error code
     * @param arg1 First argument for parametric replacement
     * @param arg2 Second argument for parametric replacement
     */
    public void jspError(String errCode, String arg1, String arg2)
	        throws JasperException {
	dispatch(null, errCode, new Object[] {arg1, arg2}, null);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param errCode Error code
     * @param arg1 First argument for parametric replacement
     * @param arg2 Second argument for parametric replacement
     * @param arg3 Third argument for parametric replacement
     */
    public void jspError(String errCode, String arg1, String arg2, String arg3)
	        throws JasperException {
	dispatch(null, errCode, new Object[] {arg1, arg2, arg3}, null);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param where Error location
     * @param errCode Error code
     * @param arg1 First argument for parametric replacement
     * @param arg2 Second argument for parametric replacement
     */
    public void jspError(Mark where, String errCode, String arg1, String arg2)
	        throws JasperException {
	dispatch(where, errCode, new Object[] {arg1, arg2}, null);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param where Error location
     * @param errCode Error code
     * @param arg1 First argument for parametric replacement
     * @param arg2 Second argument for parametric replacement
     * @param arg3 Third argument for parametric replacement
     */

    public void jspError(Mark where, String errCode, String arg1, String arg2,
                         String arg3)
                throws JasperException {
        dispatch(where, errCode, new Object[] {arg1, arg2, arg3}, null);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param n Node that caused the error
     * @param errCode Error code
     * @param arg1 First argument for parametric replacement
     * @param arg2 Second argument for parametric replacement
     */

    public void jspError(Node n, String errCode, String arg1, String arg2)
	        throws JasperException {
	dispatch(n.getStart(), errCode, new Object[] {arg1, arg2}, null);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param n Node that caused the error
     * @param errCode Error code
     * @param arg1 First argument for parametric replacement
     * @param arg2 Second argument for parametric replacement
     * @param arg3 Third argument for parametric replacement
     */

    public void jspError(Node n, String errCode, String arg1, String arg2,
                         String arg3)
	        throws JasperException {
	dispatch(n.getStart(), errCode, new Object[] {arg1, arg2, arg3}, null);
    }

    /*
     * Dispatches the given parsing exception to the configured error handler.
     *
     * @param e Parsing exception
     */
    public void jspError(Exception e) throws JasperException {
	dispatch(null, null, null, e);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param errCode Error code
     * @param arg Argument for parametric replacement
     * @param e Parsing exception
     */
    public void jspError(String errCode, String arg, Exception e)
	        throws JasperException {
	dispatch(null, errCode, new Object[] {arg}, e);
    }

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param n Node that caused the error
     * @param errCode Error code
     * @param arg Argument for parametric replacement
     * @param e Parsing exception
     */
    public void jspError(Node n, String errCode, String arg, Exception e)
	        throws JasperException {
	dispatch(n.getStart(), errCode, new Object[] {arg}, e);
    }

    /**
     * Parses the given error message into an array of javac compilation error
     * messages (one per javac compilation error line number).
     *
     * @param errMsg Error message
     * @param fname Name of Java source file whose compilation failed
     * @param page Node representation of JSP page from which the Java source
     * file was generated
     *
     * @return Array of javac compilation errors, or null if the given error
     * message does not contain any compilation error line numbers
     */
    public static JavacErrorDetail[] parseJavacErrors(String errMsg,
                                                      String fname,
                                                      Node.Nodes page)
            throws JasperException, IOException {

	return parseJavacMessage(errMsg, fname, page);
    }

    /*
     * Dispatches the given javac compilation errors to the configured error
     * handler.
     *
     * @param javacErrors Array of javac compilation errors
     */
    public void javacError(JavacErrorDetail[] javacErrors)
            throws JasperException {

        errHandler.javacError(javacErrors);
    }


    /*
     * Dispatches the given compilation error report and exception to the
     * configured error handler.
     *
     * @param errorReport Compilation error report
     * @param e Compilation exception
     */
    public void javacError(String errorReport, Exception e)
                throws JasperException {

        errHandler.javacError(errorReport, e);
    }


    //*********************************************************************
    // Private utility methods

    /*
     * Dispatches the given JSP parse error to the configured error handler.
     *
     * The given error code is localized. If it is not found in the
     * resource bundle for localized error messages, it is used as the error
     * message.
     *
     * @param where Error location
     * @param errCode Error code
     * @param args Arguments for parametric replacement
     * @param e Parsing exception
     */
    private void dispatch(Mark where, String errCode, Object[] args,
			  Exception e) throws JasperException {
	String file = null;
	String errMsg = null;
	int line = -1;
	int column = -1;
	boolean hasLocation = false;

	// Localize
	if (errCode != null) {
	    errMsg = Localizer.getMessage(errCode, args);
	} else if (e != null) {
	    // give a hint about what's wrong
	    errMsg = e.getMessage();
	}

	// Get error location
	if (where != null) {
            if (jspcMode) {
                // Get the full URL of the resource that caused the error
                try {
                    file = where.getURL().toString();
                } catch (MalformedURLException me) {
                    // Fallback to using context-relative path
                    file = where.getFile();
                }
            } else {
                // Get the context-relative resource path, so as to not
                // disclose any local filesystem details
                file = where.getFile();
            }
	    line = where.getLineNumber();
	    column = where.getColumnNumber();
	    hasLocation = true;
	}

	// Get nested exception
	Exception nestedEx = e;
	if ((e instanceof SAXException)
	        && (((SAXException) e).getException() != null)) {
	    nestedEx = ((SAXException) e).getException();
	}

	if (hasLocation) {
	    errHandler.jspError(file, line, column, errMsg, nestedEx);
	} else {
	    errHandler.jspError(errMsg, nestedEx);
	}
    }

    /*
     * Parses the given Java compilation error message, which may contain one
     * or more compilation errors, into an array of JavacErrorDetail instances.
     *
     * Each JavacErrorDetail instance contains the information about a single
     * compilation error.
     *
     * @param errMsg Compilation error message that was generated by the
     * javac compiler
     * @param fname Name of Java source file whose compilation failed
     * @param page Node representation of JSP page from which the Java source
     * file was generated
     *
     * @return Array of JavacErrorDetail instances corresponding to the
     * compilation errors
     */
    private static JavacErrorDetail[] parseJavacMessage(
                                String errMsg, String fname, Node.Nodes page)
	        throws IOException, JasperException {

        ArrayList<JavacErrorDetail> errors = new ArrayList();
        StringBuffer errMsgBuf = null;
        int lineNum = -1;
        JavacErrorDetail javacError = null;
        
        BufferedReader reader = new BufferedReader(new StringReader(errMsg));
        
        /*
         * Parse compilation errors. Each compilation error consists of a file
         * path and error line number, followed by a number of lines describing
         * the error.
         */
        String line = null;
        while ((line = reader.readLine()) != null) {
            
            /*
             * Error line number is delimited by set of colons.
             * Ignore colon following drive letter on Windows (fromIndex = 2).
             * XXX Handle deprecation warnings that don't have line info
             */
            int beginColon = line.indexOf(':', 2); 
            int endColon = line.indexOf(':', beginColon + 1);
            if ((beginColon >= 0) && (endColon >= 0)) {
                if (javacError != null) {
                    // add previous error to error vector
                    errors.add(javacError);
                }
                
                String lineNumStr = line.substring(beginColon + 1, endColon);
                try {
                    lineNum = Integer.parseInt(lineNumStr);
                } catch (NumberFormatException e) {
                    lineNum = -1;
                }
                
                errMsgBuf = new StringBuffer();
                
                javacError = createJavacError(fname, page, errMsgBuf, lineNum);
            }
            
            // Ignore messages preceding first error
            if (errMsgBuf != null) {
                errMsgBuf.append(line);
                errMsgBuf.append("\n");
            }
        }
        
        // Add last error to error vector
        if (javacError != null) {
            errors.add(javacError);
        } 
        
        reader.close();
        
        JavacErrorDetail[] errDetails = null;
        if (errors.size() > 0) {
            errDetails = new JavacErrorDetail[errors.size()];
            errors.toArray(errDetails);
        }
        
        return errDetails;
    }


    /**
     * @param fname
     * @param page
     * @param errMsgBuf
     * @param lineNum
     * @return JavacErrorDetail The error details
     * @throws JasperException
     */
    public static JavacErrorDetail createJavacError(String fname,
            Node.Nodes page, StringBuffer errMsgBuf, int lineNum)
    throws JasperException {
        return createJavacError(fname, page, errMsgBuf, lineNum, null);
    }
    
    
    /**
     * @param fname
     * @param page
     * @param errMsgBuf
     * @param lineNum
     * @param ctxt
     * @return JavacErrorDetail The error details
     * @throws JasperException
     */
    public static JavacErrorDetail createJavacError(String fname,
            Node.Nodes page, StringBuffer errMsgBuf, int lineNum,
            JspCompilationContext ctxt) throws JasperException {
        JavacErrorDetail javacError;
        // Attempt to map javac error line number to line in JSP page
        ErrorVisitor errVisitor = new ErrorVisitor(lineNum);
        page.visit(errVisitor);
        Node errNode = errVisitor.getJspSourceNode();
        if ((errNode != null) && (errNode.getStart() != null)) {
            // If this is a scriplet node then there is a one to one mapping
            // between JSP lines and Java lines
            if (errVisitor.getJspSourceNode() instanceof Node.Scriptlet) {
                javacError = new JavacErrorDetail(
                        fname,
                        lineNum,
                        errNode.getStart().getFile(),
                        errNode.getStart().getLineNumber() + lineNum -
                            errVisitor.getJspSourceNode().getBeginJavaLine(),
                        errMsgBuf,
                        ctxt);
            } else {
                javacError = new JavacErrorDetail(
                        fname,
                        lineNum,
                        errNode.getStart().getFile(),
                        errNode.getStart().getLineNumber(),
                        errMsgBuf,
                        ctxt);
            }
        } else {
            /*
             * javac error line number cannot be mapped to JSP page
             * line number. For example, this is the case if a 
             * scriptlet is missing a closing brace, which causes
             * havoc with the try-catch-finally block that the code
             * generator places around all generated code: As a result
             * of this, the javac error line numbers will be outside
             * the range of begin and end java line numbers that were
             * generated for the scriptlet, and therefore cannot be
             * mapped to the start line number of the scriptlet in the
             * JSP page.
             * Include just the javac error info in the error detail.
             */
            javacError = new JavacErrorDetail(
                    fname,
                    lineNum,
                    errMsgBuf);
        }
        return javacError;
    }


    /*
     * Visitor responsible for mapping a line number in the generated servlet
     * source code to the corresponding JSP node.
     */
    static class ErrorVisitor extends Node.Visitor {

	// Java source line number to be mapped
	private int lineNum;

	/*
	 * JSP node whose Java source code range in the generated servlet
	 * contains the Java source line number to be mapped
	 */
	Node found;

	/*
	 * Constructor.
	 *
	 * @param lineNum Source line number in the generated servlet code
	 */
	public ErrorVisitor(int lineNum) {
	    this.lineNum = lineNum;
	}

	public void doVisit(Node n) throws JasperException {
	    if ((lineNum >= n.getBeginJavaLine())
		    && (lineNum < n.getEndJavaLine())) {
		found = n;
	    }
        }

	/*
	 * Gets the JSP node to which the source line number in the generated
	 * servlet code was mapped.
	 *
	 * @return JSP node to which the source line number in the generated
	 * servlet code was mapped
	 */
	public Node getJspSourceNode() {
	    return found;
	}
    }
}