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Android example source code file (Base64OutputStream.java)

This example Android source code file (Base64OutputStream.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

base64outputstream, empty, filteroutputstream, io, ioexception

The Base64OutputStream.java Android example source code

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * 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 android.util;

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * An OutputStream that does Base64 encoding on the data written to
 * it, writing the resulting data to another OutputStream.
 */
public class Base64OutputStream extends FilterOutputStream {
    private final Base64.Coder coder;
    private final int flags;

    private byte[] buffer = null;
    private int bpos = 0;

    private static byte[] EMPTY = new byte[0];

    /**
     * Performs Base64 encoding on the data written to the stream,
     * writing the encoded data to another OutputStream.
     *
     * @param out the OutputStream to write the encoded data to
     * @param flags bit flags for controlling the encoder; see the
     *        constants in {@link Base64}
     */
    public Base64OutputStream(OutputStream out, int flags) {
        this(out, flags, true);
    }

    /**
     * Performs Base64 encoding or decoding on the data written to the
     * stream, writing the encoded/decoded data to another
     * OutputStream.
     *
     * @param out the OutputStream to write the encoded data to
     * @param flags bit flags for controlling the encoder; see the
     *        constants in {@link Base64}
     * @param encode true to encode, false to decode
     *
     * @hide
     */
    public Base64OutputStream(OutputStream out, int flags, boolean encode) {
        super(out);
        this.flags = flags;
        if (encode) {
            coder = new Base64.Encoder(flags, null);
        } else {
            coder = new Base64.Decoder(flags, null);
        }
    }

    public void write(int b) throws IOException {
        // To avoid invoking the encoder/decoder routines for single
        // bytes, we buffer up calls to write(int) in an internal
        // byte array to transform them into writes of decently-sized
        // arrays.

        if (buffer == null) {
            buffer = new byte[1024];
        }
        if (bpos >= buffer.length) {
            // internal buffer full; write it out.
            internalWrite(buffer, 0, bpos, false);
            bpos = 0;
        }
        buffer[bpos++] = (byte) b;
    }

    /**
     * Flush any buffered data from calls to write(int).  Needed
     * before doing a write(byte[], int, int) or a close().
     */
    private void flushBuffer() throws IOException {
        if (bpos > 0) {
            internalWrite(buffer, 0, bpos, false);
            bpos = 0;
        }
    }

    public void write(byte[] b, int off, int len) throws IOException {
        if (len <= 0) return;
        flushBuffer();
        internalWrite(b, off, len, false);
    }

    public void close() throws IOException {
        IOException thrown = null;
        try {
            flushBuffer();
            internalWrite(EMPTY, 0, 0, true);
        } catch (IOException e) {
            thrown = e;
        }

        try {
            if ((flags & Base64.NO_CLOSE) == 0) {
                out.close();
            } else {
                out.flush();
            }
        } catch (IOException e) {
            if (thrown != null) {
                thrown = e;
            }
        }

        if (thrown != null) {
            throw thrown;
        }
    }

    /**
     * Write the given bytes to the encoder/decoder.
     *
     * @param finish true if this is the last batch of input, to cause
     *        encoder/decoder state to be finalized.
     */
    private void internalWrite(byte[] b, int off, int len, boolean finish) throws IOException {
        coder.output = embiggen(coder.output, coder.maxOutputSize(len));
        if (!coder.process(b, off, len, finish)) {
            throw new IOException("bad base-64");
        }
        out.write(coder.output, 0, coder.op);
    }

    /**
     * If b.length is at least len, return b.  Otherwise return a new
     * byte array of length len.
     */
    private byte[] embiggen(byte[] b, int len) {
        if (b == null || b.length < len) {
            return new byte[len];
        } else {
            return b;
        }
    }
}

Other Android examples (source code examples)

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