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Java example source code file (AsciiHeadersEncoder.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

asciiheadersencoder, asciistring, bytebuf, charsequence, colon_space, crlf, error, newlinetype, nullpointerexception, separatortype

The AsciiHeadersEncoder.java Java example source code

/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project 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 io.netty.handler.codec;


import java.util.Map.Entry;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufUtil;
import io.netty.util.AsciiString;

public final class AsciiHeadersEncoder {

    /**
     * The separator characters to insert between a header name and a header value.
     */
    public enum SeparatorType {
        /**
         * {@code ':'}
         */
        COLON,
        /**
         * {@code ': '}
         */
        COLON_SPACE,
    }

    /**
     * The newline characters to insert between header entries.
     */
    public enum NewlineType {
        /**
         * {@code '\n'}
         */
        LF,
        /**
         * {@code '\r\n'}
         */
        CRLF
    }

    private final ByteBuf buf;
    private final SeparatorType separatorType;
    private final NewlineType newlineType;

    public AsciiHeadersEncoder(ByteBuf buf) {
        this(buf, SeparatorType.COLON_SPACE, NewlineType.CRLF);
    }

    public AsciiHeadersEncoder(ByteBuf buf, SeparatorType separatorType, NewlineType newlineType) {
        if (buf == null) {
            throw new NullPointerException("buf");
        }
        if (separatorType == null) {
            throw new NullPointerException("separatorType");
        }
        if (newlineType == null) {
            throw new NullPointerException("newlineType");
        }

        this.buf = buf;
        this.separatorType = separatorType;
        this.newlineType = newlineType;
    }

    public void encode(Entry<CharSequence, CharSequence> entry) {
        final CharSequence name = entry.getKey();
        final CharSequence value = entry.getValue();
        final ByteBuf buf = this.buf;
        final int nameLen = name.length();
        final int valueLen = value.length();
        final int entryLen = nameLen + valueLen + 4;
        int offset = buf.writerIndex();
        buf.ensureWritable(entryLen);
        writeAscii(buf, offset, name, nameLen);
        offset += nameLen;

        switch (separatorType) {
            case COLON:
                buf.setByte(offset ++, ':');
                break;
            case COLON_SPACE:
                buf.setByte(offset ++, ':');
                buf.setByte(offset ++, ' ');
                break;
            default:
                throw new Error();
        }

        writeAscii(buf, offset, value, valueLen);
        offset += valueLen;

        switch (newlineType) {
            case LF:
                buf.setByte(offset ++, '\n');
                break;
            case CRLF:
                buf.setByte(offset ++, '\r');
                buf.setByte(offset ++, '\n');
                break;
            default:
                throw new Error();
        }

        buf.writerIndex(offset);
    }

    private static void writeAscii(ByteBuf buf, int offset, CharSequence value, int valueLen) {
        if (value instanceof AsciiString) {
            writeAsciiString(buf, offset, (AsciiString) value, valueLen);
        } else {
            writeCharSequence(buf, offset, value, valueLen);
        }
    }

    private static void writeAsciiString(ByteBuf buf, int offset, AsciiString value, int valueLen) {
        ByteBufUtil.copy(value, 0, buf, offset, valueLen);
    }

    private static void writeCharSequence(ByteBuf buf, int offset, CharSequence value, int valueLen) {
        for (int i = 0; i < valueLen; i ++) {
            buf.setByte(offset ++, c2b(value.charAt(i)));
        }
    }

    private static int c2b(char ch) {
        return ch < 256? (byte) ch : '?';
    }
}

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