Tomcat example source code file (Compiler.java)

This example Tomcat source code file (Compiler.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

deleting, errordispatcher, exception, exception, file, file, filenotfoundexception, filenotfoundexception, io, jasperexception, net, network, outputstreamwriter, pageinfo, servletwriter, string, string, util

The Tomcat Compiler.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.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.net.URLConnection;
import java.util.Iterator;
import java.util.List;

import org.apache.jasper.JasperException;
import org.apache.jasper.JspCompilationContext;
import org.apache.jasper.Options;
import org.apache.jasper.servlet.JspServletWrapper;

/**
 * Main JSP compiler class. This class uses Ant for compiling.
 * 
 * @author Anil K. Vijendran
 * @author Mandar Raje
 * @author Pierre Delisle
 * @author Kin-man Chung
 * @author Remy Maucherat
 * @author Mark Roth
 */
public abstract class Compiler {
    
    protected org.apache.juli.logging.Log log = org.apache.juli.logging.LogFactory
            .getLog(Compiler.class);

    // ----------------------------------------------------- Instance Variables

    protected JspCompilationContext ctxt;

    protected ErrorDispatcher errDispatcher;

    protected PageInfo pageInfo;

    protected JspServletWrapper jsw;

    protected TagFileProcessor tfp;

    protected Options options;

    protected Node.Nodes pageNodes;

    // ------------------------------------------------------------ Constructor

    public void init(JspCompilationContext ctxt, JspServletWrapper jsw) {
        this.jsw = jsw;
        this.ctxt = ctxt;
        this.options = ctxt.getOptions();
    }

    // --------------------------------------------------------- Public Methods

    /**
     * <p>
     * Retrieves the parsed nodes of the JSP page, if they are available. May
     * return null. Used in development mode for generating detailed error
     * messages. http://issues.apache.org/bugzilla/show_bug.cgi?id=37062.
     * </p>
     */
    public Node.Nodes getPageNodes() {
        return this.pageNodes;
    }

    /**
     * Compile the jsp file into equivalent servlet in .java file
     * 
     * @return a smap for the current JSP page, if one is generated, null
     *         otherwise
     */
    protected String[] generateJava() throws Exception {

        String[] smapStr = null;

        long t1, t2, t3, t4;

        t1 = t2 = t3 = t4 = 0;

        if (log.isDebugEnabled()) {
            t1 = System.currentTimeMillis();
        }

        // Setup page info area
        pageInfo = new PageInfo(new BeanRepository(ctxt.getClassLoader(),
                errDispatcher), ctxt.getJspFile());

        JspConfig jspConfig = options.getJspConfig();
        JspConfig.JspProperty jspProperty = jspConfig.findJspProperty(ctxt
                .getJspFile());

        /*
         * If the current uri is matched by a pattern specified in a
         * jsp-property-group in web.xml, initialize pageInfo with those
         * properties.
         */
        if (jspProperty.isELIgnored() != null) {
            pageInfo.setELIgnored(JspUtil.booleanValue(jspProperty
                    .isELIgnored()));
        }
        if (jspProperty.isScriptingInvalid() != null) {
            pageInfo.setScriptingInvalid(JspUtil.booleanValue(jspProperty
                    .isScriptingInvalid()));
        }
        if (jspProperty.getIncludePrelude() != null) {
            pageInfo.setIncludePrelude(jspProperty.getIncludePrelude());
        }
        if (jspProperty.getIncludeCoda() != null) {
            pageInfo.setIncludeCoda(jspProperty.getIncludeCoda());
        }
        if (jspProperty.isDeferedSyntaxAllowedAsLiteral() != null) {
            pageInfo.setDeferredSyntaxAllowedAsLiteral(JspUtil.booleanValue(jspProperty
                    .isDeferedSyntaxAllowedAsLiteral()));
        }
        if (jspProperty.isTrimDirectiveWhitespaces() != null) {
            pageInfo.setTrimDirectiveWhitespaces(JspUtil.booleanValue(jspProperty
                    .isTrimDirectiveWhitespaces()));
        }

        ctxt.checkOutputDir();
        String javaFileName = ctxt.getServletJavaFileName();

        ServletWriter writer = null;
        try {

            // Reset the temporary variable counter for the generator.
            JspUtil.resetTemporaryVariableName();

            // Parse the file
            ParserController parserCtl = new ParserController(ctxt, this);
            pageNodes = parserCtl.parse(ctxt.getJspFile());

            if (ctxt.isPrototypeMode()) {
                // generate prototype .java file for the tag file
                writer = setupContextWriter(javaFileName);
                Generator.generate(writer, this, pageNodes);
                writer.close();
                writer = null;
                return null;
            }

            // Validate and process attributes
            Validator.validate(this, pageNodes);

            if (log.isDebugEnabled()) {
                t2 = System.currentTimeMillis();
            }

            // Collect page info
            Collector.collect(this, pageNodes);

            // Compile (if necessary) and load the tag files referenced in
            // this compilation unit.
            tfp = new TagFileProcessor();
            tfp.loadTagFiles(this, pageNodes);

            if (log.isDebugEnabled()) {
                t3 = System.currentTimeMillis();
            }

            // Determine which custom tag needs to declare which scripting vars
            ScriptingVariabler.set(pageNodes, errDispatcher);

            // Optimizations by Tag Plugins
            TagPluginManager tagPluginManager = options.getTagPluginManager();
            tagPluginManager.apply(pageNodes, errDispatcher, pageInfo);

            // Optimization: concatenate contiguous template texts.
            TextOptimizer.concatenate(this, pageNodes);

            // Generate static function mapper codes.
            ELFunctionMapper.map(this, pageNodes);

            // generate servlet .java file
            writer = setupContextWriter(javaFileName);
            Generator.generate(writer, this, pageNodes);
            writer.close();
            writer = null;

            // The writer is only used during the compile, dereference
            // it in the JspCompilationContext when done to allow it
            // to be GC'd and save memory.
            ctxt.setWriter(null);

            if (log.isDebugEnabled()) {
                t4 = System.currentTimeMillis();
                log.debug("Generated " + javaFileName + " total=" + (t4 - t1)
                        + " generate=" + (t4 - t3) + " validate=" + (t2 - t1));
            }

        } catch (Exception e) {
            if (writer != null) {
                try {
                    writer.close();
                    writer = null;
                } catch (Exception e1) {
                    // do nothing
                }
            }
            // Remove the generated .java file
            new File(javaFileName).delete();
            throw e;
        } finally {
            if (writer != null) {
                try {
                    writer.close();
                } catch (Exception e2) {
                    // do nothing
                }
            }
        }

        // JSR45 Support
        if (!options.isSmapSuppressed()) {
            smapStr = SmapUtil.generateSmap(ctxt, pageNodes);
        }

        // If any proto type .java and .class files was generated,
        // the prototype .java may have been replaced by the current
        // compilation (if the tag file is self referencing), but the
        // .class file need to be removed, to make sure that javac would
        // generate .class again from the new .java file just generated.
        tfp.removeProtoTypeFiles(ctxt.getClassFileName());

        return smapStr;
    }

	private ServletWriter setupContextWriter(String javaFileName)
			throws FileNotFoundException, JasperException {
		ServletWriter writer;
		// Setup the ServletWriter
		String javaEncoding = ctxt.getOptions().getJavaEncoding();
		OutputStreamWriter osw = null;

		try {
		    osw = new OutputStreamWriter(
		            new FileOutputStream(javaFileName), javaEncoding);
		} catch (UnsupportedEncodingException ex) {
		    errDispatcher.jspError("jsp.error.needAlternateJavaEncoding",
		            javaEncoding);
		}

		writer = new ServletWriter(new PrintWriter(osw));
		ctxt.setWriter(writer);
		return writer;
	}

    /**
     * Compile the servlet from .java file to .class file
     */
    protected abstract void generateClass(String[] smap)
            throws FileNotFoundException, JasperException, Exception;

    /**
     * Compile the jsp file from the current engine context
     */
    public void compile() throws FileNotFoundException, JasperException,
            Exception {
        compile(true);
    }

    /**
     * Compile the jsp file from the current engine context. As an side- effect,
     * tag files that are referenced by this page are also compiled.
     * 
     * @param compileClass
     *            If true, generate both .java and .class file If false,
     *            generate only .java file
     */
    public void compile(boolean compileClass) throws FileNotFoundException,
            JasperException, Exception {
        compile(compileClass, false);
    }

    /**
     * Compile the jsp file from the current engine context. As an side- effect,
     * tag files that are referenced by this page are also compiled.
     * 
     * @param compileClass
     *            If true, generate both .java and .class file If false,
     *            generate only .java file
     * @param jspcMode
     *            true if invoked from JspC, false otherwise
     */
    public void compile(boolean compileClass, boolean jspcMode)
            throws FileNotFoundException, JasperException, Exception {
        if (errDispatcher == null) {
            this.errDispatcher = new ErrorDispatcher(jspcMode);
        }

        try {
            String[] smap = generateJava();
            if (compileClass) {
                generateClass(smap);
            }
        } finally {
            if (tfp != null) {
                tfp.removeProtoTypeFiles(null);
            }
            // Make sure these object which are only used during the
            // generation and compilation of the JSP page get
            // dereferenced so that they can be GC'd and reduce the
            // memory footprint.
            tfp = null;
            errDispatcher = null;
            pageInfo = null;

            // Only get rid of the pageNodes if in production.
            // In development mode, they are used for detailed
            // error messages.
            // http://issues.apache.org/bugzilla/show_bug.cgi?id=37062
            if (!this.options.getDevelopment()) {
                pageNodes = null;
            }

            if (ctxt.getWriter() != null) {
                ctxt.getWriter().close();
                ctxt.setWriter(null);
            }
        }
    }

    /**
     * This is a protected method intended to be overridden by subclasses of
     * Compiler. This is used by the compile method to do all the compilation.
     */
    public boolean isOutDated() {
        return isOutDated(true);
    }

    /**
     * Determine if a compilation is necessary by checking the time stamp of the
     * JSP page with that of the corresponding .class or .java file. If the page
     * has dependencies, the check is also extended to its dependeants, and so
     * on. This method can by overidden by a subclasses of Compiler.
     * 
     * @param checkClass
     *            If true, check against .class file, if false, check against
     *            .java file.
     */
    public boolean isOutDated(boolean checkClass) {

        String jsp = ctxt.getJspFile();

        if (jsw != null
                && (ctxt.getOptions().getModificationTestInterval() > 0)) {

            if (jsw.getLastModificationTest()
                    + (ctxt.getOptions().getModificationTestInterval() * 1000) > System
                    .currentTimeMillis()) {
                return false;
            } else {
                jsw.setLastModificationTest(System.currentTimeMillis());
            }
        }

        long jspRealLastModified = 0;
        try {
            URL jspUrl = ctxt.getResource(jsp);
            if (jspUrl == null) {
                ctxt.incrementRemoved();
                return false;
            }
            URLConnection uc = jspUrl.openConnection();
            jspRealLastModified = uc.getLastModified();
            uc.getInputStream().close();
        } catch (Exception e) {
            return true;
        }

        long targetLastModified = 0;
        File targetFile;

        if (checkClass) {
            targetFile = new File(ctxt.getClassFileName());
        } else {
            targetFile = new File(ctxt.getServletJavaFileName());
        }

        if (!targetFile.exists()) {
            return true;
        }

        targetLastModified = targetFile.lastModified();
        if (checkClass && jsw != null) {
            jsw.setServletClassLastModifiedTime(targetLastModified);
        }
        if (targetLastModified < jspRealLastModified) {
            if (log.isDebugEnabled()) {
                log.debug("Compiler: outdated: " + targetFile + " "
                        + targetLastModified);
            }
            return true;
        }

        // determine if source dependent files (e.g. includes using include
        // directives) have been changed.
        if (jsw == null) {
            return false;
        }

        List depends = jsw.getDependants();
        if (depends == null) {
            return false;
        }

        Iterator it = depends.iterator();
        while (it.hasNext()) {
            String include = (String) it.next();
            try {
                URL includeUrl = ctxt.getResource(include);
                if (includeUrl == null) {
                    return true;
                }

                URLConnection includeUconn = includeUrl.openConnection();
                long includeLastModified = includeUconn.getLastModified();
                includeUconn.getInputStream().close();

                if (includeLastModified > targetLastModified) {
                    return true;
                }
            } catch (Exception e) {
                return true;
            }
        }

        return false;

    }

    /**
     * Gets the error dispatcher.
     */
    public ErrorDispatcher getErrorDispatcher() {
        return errDispatcher;
    }

    /**
     * Gets the info about the page under compilation
     */
    public PageInfo getPageInfo() {
        return pageInfo;
    }

    public JspCompilationContext getCompilationContext() {
        return ctxt;
    }

    /**
     * Remove generated files
     */
    public void removeGeneratedFiles() {
        try {
            String classFileName = ctxt.getClassFileName();
            if (classFileName != null) {
                File classFile = new File(classFileName);
                if (log.isDebugEnabled())
                    log.debug("Deleting " + classFile);
                classFile.delete();
            }
        } catch (Exception e) {
            // Remove as much as possible, ignore possible exceptions
        }
        try {
            String javaFileName = ctxt.getServletJavaFileName();
            if (javaFileName != null) {
                File javaFile = new File(javaFileName);
                if (log.isDebugEnabled())
                    log.debug("Deleting " + javaFile);
                javaFile.delete();
            }
        } catch (Exception e) {
            // Remove as much as possible, ignore possible exceptions
        }
    }

    public void removeGeneratedClassFiles() {
        try {
            String classFileName = ctxt.getClassFileName();
            if (classFileName != null) {
                File classFile = new File(classFileName);
                if (log.isDebugEnabled())
                    log.debug("Deleting " + classFile);
                classFile.delete();
            }
        } catch (Exception e) {
            // Remove as much as possible, ignore possible exceptions
        }
    }
}