checksum.java

java ant的源码！非常值得看的源码

/*
 *  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.tools.ant.taskdefs;

import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.BufferedReader;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Iterator;
import java.util.Hashtable;
import java.util.Enumeration;
import java.util.Set;
import java.util.Arrays;
import java.text.MessageFormat;
import java.text.ParseException;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.taskdefs.condition.Condition;
import org.apache.tools.ant.types.EnumeratedAttribute;
import org.apache.tools.ant.types.FileSet;
import org.apache.tools.ant.types.ResourceCollection;
import org.apache.tools.ant.types.resources.Union;
import org.apache.tools.ant.types.resources.Restrict;
import org.apache.tools.ant.types.resources.FileResource;
import org.apache.tools.ant.types.resources.selectors.Type;
import org.apache.tools.ant.util.FileUtils;
import org.apache.tools.ant.util.StringUtils;

/**
 * Used to create or verify file checksums.
 *
 * @since Ant 1.5
 *
 * @ant.task category="control"
 */
public class Checksum extends MatchingTask implements Condition {
    private static class FileUnion extends Restrict {
        private Union u;
        FileUnion() {
            u = new Union();
            super.add(u);
            super.add(Type.FILE);
        }
        public void add(ResourceCollection rc) {
            u.add(rc);
        }
    }

    /**
     * File for which checksum is to be calculated.
     */
    private File file = null;

    /**
     * Root directory in which the checksum files will be written.
     * If not specified, the checksum files will be written
     * in the same directory as each file.
     */
    private File todir;

    /**
     * MessageDigest algorithm to be used.
     */
    private String algorithm = "MD5";
    /**
     * MessageDigest Algorithm provider
     */
    private String provider = null;
    /**
     * File Extension that is be to used to create or identify
     * destination file
     */
    private String fileext;
    /**
     * Holds generated checksum and gets set as a Project Property.
     */
    private String property;
    /**
     * Holds checksums for all files (both calculated and cached on disk).
     * Key:   java.util.File (source file)
     * Value: java.lang.String (digest)
     */
    private Map allDigests = new HashMap();
    /**
     * Holds relative file names for all files (always with a forward slash).
     * This is used to calculate the total hash.
     * Key:   java.util.File (source file)
     * Value: java.lang.String (relative file name)
     */
    private Map relativeFilePaths = new HashMap();
    /**
     * Property where totalChecksum gets set.
     */
    private String totalproperty;
    /**
     * Whether or not to create a new file.
     * Defaults to <code>false</code>.
     */
    private boolean forceOverwrite;
    /**
     * Contains the result of a checksum verification. ("true" or "false")
     */
    private String verifyProperty;
    /**
     * Resource Collection.
     */
    private FileUnion resources = null;
    /**
     * Stores SourceFile, DestFile pairs and SourceFile, Property String pairs.
     */
    private Hashtable includeFileMap = new Hashtable();
    /**
     * Message Digest instance
     */
    private MessageDigest messageDigest;
    /**
     * is this task being used as a nested condition element?
     */
    private boolean isCondition;
    /**
     * Size of the read buffer to use.
     */
    private int readBufferSize = 8 * 1024;

    /**
     * Formater for the checksum file.
     */
    private MessageFormat format = FormatElement.getDefault().getFormat();

    /**
     * Sets the file for which the checksum is to be calculated.
     * @param file a <code>File</code> value
     */
    public void setFile(File file) {
        this.file = file;
    }

    /**
     * Sets the root directory where checksum files will be
     * written/read
     * @param todir the directory to write to
     * @since Ant 1.6
     */
    public void setTodir(File todir) {
        this.todir = todir;
    }

    /**
     * Specifies the algorithm to be used to compute the checksum.
     * Defaults to "MD5". Other popular algorithms like "SHA" may be used as well.
     * @param algorithm a <code>String</code> value
     */
    public void setAlgorithm(String algorithm) {
        this.algorithm = algorithm;
    }

    /**
     * Sets the MessageDigest algorithm provider to be used
     * to calculate the checksum.
     * @param provider a <code>String</code> value
     */
    public void setProvider(String provider) {
        this.provider = provider;
    }

    /**
     * Sets the file extension that is be to used to
     * create or identify destination file.
     * @param fileext a <code>String</code> value
     */
    public void setFileext(String fileext) {
        this.fileext = fileext;
    }

    /**
     * Sets the property to hold the generated checksum.
     * @param property a <code>String</code> value
     */
    public void setProperty(String property) {
        this.property = property;
    }

    /**
     * Sets the property to hold the generated total checksum
     * for all files.
     * @param totalproperty a <code>String</code> value
     *
     * @since Ant 1.6
     */
    public void setTotalproperty(String totalproperty) {
        this.totalproperty = totalproperty;
    }

    /**
     * Sets the verify property.  This project property holds
     * the result of a checksum verification - "true" or "false"
     * @param verifyProperty a <code>String</code> value
     */
    public void setVerifyproperty(String verifyProperty) {
        this.verifyProperty = verifyProperty;
    }

    /**
     * Whether or not to overwrite existing file irrespective of
     * whether it is newer than
     * the source file.  Defaults to false.
     * @param forceOverwrite a <code>boolean</code> value
     */
    public void setForceOverwrite(boolean forceOverwrite) {
        this.forceOverwrite = forceOverwrite;
    }

    /**
     * The size of the read buffer to use.
     * @param size an <code>int</code> value
     */
    public void setReadBufferSize(int size) {
        this.readBufferSize = size;
    }

    /**
     * Select the in/output pattern via a well know format name.
     * @param e an <code>enumerated</code> value
     *
     * @since 1.7.0
     */
    public void setFormat(FormatElement e) {
        format = e.getFormat();
    }

    /**
     * Specify the pattern to use as a MessageFormat pattern.
     *
     * <p>{0} gets replaced by the checksum, {1} by the filename.</p>
     * @param p a <code>String</code> value
     *
     * @since 1.7.0
     */
    public void setPattern(String p) {
        format = new MessageFormat(p);
    }

    /**
     * Files to generate checksums for.
     * @param set a fileset of files to generate checksums for.
     */
    public void addFileset(FileSet set) {
        add(set);
    }

    /**
     * Add a resource collection.
     * @param rc the ResourceCollection to add.
     */
    public void add(ResourceCollection rc) {
        if (rc == null) {
            return;
        }
        resources = (resources == null) ? new FileUnion() : resources;
        resources.add(rc);
    }

    /**
     * Calculate the checksum(s).
     * @throws BuildException on error
     */
    public void execute() throws BuildException {
        isCondition = false;
        boolean value = validateAndExecute();
        if (verifyProperty != null) {
            getProject().setNewProperty(
                verifyProperty,
                (value ? Boolean.TRUE.toString() : Boolean.FALSE.toString()));
        }
    }

    /**
     * Calculate the checksum(s)
     *
     * @return Returns true if the checksum verification test passed,
     * false otherwise.
     * @throws BuildException on error
     */
    public boolean eval() throws BuildException {
        isCondition = true;
        return validateAndExecute();
    }

    /**
     * Validate attributes and get down to business.
     */
    private boolean validateAndExecute() throws BuildException {
        String savedFileExt = fileext;

        if (file == null && (resources == null || resources.size() == 0)) {
            throw new BuildException(
                "Specify at least one source - a file or a resource collection.");
        }
        if (!(resources == null || resources.isFilesystemOnly())) {
            throw new BuildException("Can only calculate checksums for file-based resources.");
        }
        if (file != null && file.exists() && file.isDirectory()) {
            throw new BuildException("Checksum cannot be generated for directories");
        }
        if (file != null && totalproperty != null) {
            throw new BuildException("File and Totalproperty cannot co-exist.");
        }
        if (property != null && fileext != null) {
            throw new BuildException("Property and FileExt cannot co-exist.");
        }
        if (property != null) {
            if (forceOverwrite) {
                throw new BuildException(
                    "ForceOverwrite cannot be used when Property is specified");
            }
            int ct = 0;
            if (resources != null) {
                ct += resources.size();
            }
            if (file != null) {