com.adaptris.util.text.mime.ReadonlyFileDataSource.java Source code

Introduction

Here is the source code for com.adaptris.util.text.mime.ReadonlyFileDataSource.java

Source

/*
 * Copyright 2018 Adaptris Ltd.
 * 
 * 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 com.adaptris.util.text.mime;

import java.io.BufferedInputStream;
import java.io.Closeable;
import java.io.File;
import java.io.FileInputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

import javax.activation.DataSource;
import javax.mail.MessagingException;
import javax.mail.internet.InternetHeaders;
import javax.mail.internet.SharedInputStream;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang.StringUtils;

import com.adaptris.core.util.Args;

class ReadonlyFileDataSource implements DataSource, Closeable, MimeConstants, MimeHeaders {

    private transient File wrappedFile;
    private transient List<SharedFileInputStream> children;
    private transient InternetHeaders headers;
    private transient String contentType = null;
    private transient String messageId = null;

    ReadonlyFileDataSource(File f) throws IOException, MessagingException {
        wrappedFile = f;
        headers = readHeaders(wrappedFile);
        children = new ArrayList<>();

    }

    private static InternetHeaders readHeaders(File f) throws IOException, MessagingException {
        InternetHeaders hdrs = null;
        try (InputStream in = new FileInputStream(f)) {
            hdrs = new InternetHeaders(in);
        }
        return hdrs;
    }

    @Override
    public String getContentType() {
        if (contentType == null) {
            contentType = get(HEADER_CONTENT_TYPE);
        }
        return contentType;
    }

    @Override
    public InputStream getInputStream() throws IOException {
        SharedFileInputStream child = new SharedFileInputStream();
        children.add(child);
        return child;
    }

    @Override
    public String getName() {
        if (messageId == null) {
            messageId = get(HEADER_MESSAGE_ID);
        }
        return messageId;
    }

    private String get(String headerName) {
        String result = null;
        try {
            String[] s = Args.notNull(headers.getHeader(headerName), headerName);
            result = s[0];
        } catch (IllegalArgumentException e) {

        }
        return StringUtils.defaultIfEmpty(result, "");
    }

    @Override
    public OutputStream getOutputStream() throws IOException {
        throw new UnsupportedOperationException();
    }

    @Override
    @SuppressWarnings("deprecation")
    public void close() throws IOException {
        for (SharedFileInputStream child : children) {
            IOUtils.closeQuietly(child);
        }
    }

    @Override
    public InternetHeaders getHeaders() {
        return headers;
    }

    private class SharedFileInputStream extends FilterInputStream implements SharedInputStream {
        private final long myStart;
        private final long myLength;

        private long currentPos;
        private long markedPos;

        public SharedFileInputStream() throws IOException {
            this(0, wrappedFile.length());
        }

        private SharedFileInputStream(long start, long length) throws IOException {
            super(new BufferedInputStream(new FileInputStream(wrappedFile)));
            myStart = start;
            myLength = length;
            in.skip(start);
        }

        public long getPosition() {
            return currentPos;
        }

        public InputStream newStream(long start, long finish) {
            SharedFileInputStream stream = null;

            try {
                if (finish < 0) {
                    if (myLength > 0) {
                        stream = new SharedFileInputStream(myStart + start, myLength - start);
                    } else if (myLength == 0) {
                        stream = new SharedFileInputStream(myStart + start, 0);
                    } else {
                        stream = new SharedFileInputStream(myStart + start, -1);
                    }
                } else {
                    stream = new SharedFileInputStream(myStart + start, finish - start);
                }
                children.add(stream);
            } catch (IOException e) {
                throw new IllegalStateException(e);
            }
            return stream;

        }

        public int read(byte[] buf) throws IOException {
            return this.read(buf, 0, buf.length);
        }

        public int read(byte[] buf, int off, int len) throws IOException {
            if ((currentPos + len) > myLength) {
                // we would read past the end of what we're allowed to.
                // so just read the rest of it.
                return read(buf, off, Long.valueOf(myLength - currentPos).intValue());
            }
            int bytesRead = in.read(buf, off, len);
            if (bytesRead == 0) {
                return -1;
            }
            currentPos += bytesRead;
            return bytesRead;
        }

        public int read() throws IOException {
            if (currentPos == myLength) {
                return -1;
            }
            currentPos++;
            return in.read();
        }

        public boolean markSupported() {
            return true;
        }

        public long skip(long n) throws IOException {
            long count;
            for (count = 0; count != n; count++) {
                if (this.read() < 0) {
                    break;
                }
            }
            return count;
        }

        public synchronized void mark(int readLimit) {
            markedPos = currentPos;
            in.mark(readLimit);
        }

        public synchronized void reset() throws IOException {
            currentPos = markedPos;
            in.reset();
        }
    }

}