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Java example source code file (SmtpRequestEncoder.java)

This example Java source code file (SmtpRequestEncoder.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

bytebuf, crlf, dot_crlf, exception, illegalstateexception, messagetomessageencoder, object, override, randomaccess, smtpcontent, smtprequest, smtprequestencoder, unstableapi, util

The SmtpRequestEncoder.java Java example source code

/*
 * Copyright 2016 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.smtp;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufUtil;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageEncoder;
import io.netty.util.internal.UnstableApi;

import java.util.Iterator;
import java.util.List;
import java.util.RandomAccess;

/**
 * Encoder for SMTP requests.
 */
@UnstableApi
public final class SmtpRequestEncoder extends MessageToMessageEncoder<Object> {
    private static final byte[] CRLF = {'\r', '\n'};
    private static final byte[] DOT_CRLF = {'.', '\r', '\n'};
    private static final byte SP = ' ';
    private static final ByteBuf DOT_CRLF_BUFFER = Unpooled.unreleasableBuffer(
            Unpooled.directBuffer(3).writeBytes(DOT_CRLF));

    private boolean contentExpected;

    @Override
    public boolean acceptOutboundMessage(Object msg) throws Exception {
        return msg instanceof SmtpRequest || msg instanceof SmtpContent;
    }

    @Override
    protected void encode(ChannelHandlerContext ctx, Object msg, List<Object> out) throws Exception {
        if (msg instanceof SmtpRequest) {
            if (contentExpected) {
                throw new IllegalStateException("SmtpContent expected");
            }
            boolean release = true;
            final ByteBuf buffer = ctx.alloc().buffer();
            try {
                final SmtpRequest req = (SmtpRequest) msg;
                req.command().encode(buffer);
                writeParameters(req.parameters(), buffer);
                buffer.writeBytes(CRLF);
                out.add(buffer);
                release = false;
                if (req.command().isContentExpected()) {
                    contentExpected = true;
                }
            } finally {
                if (release) {
                    buffer.release();
                }
            }
        }

        if (msg instanceof SmtpContent) {
            if (!contentExpected) {
                throw new IllegalStateException("No SmtpContent expected");
            }
            final ByteBuf content = ((SmtpContent) msg).content();
            out.add(content.retain());
            if (msg instanceof LastSmtpContent) {
                out.add(DOT_CRLF_BUFFER.retainedDuplicate());
                contentExpected = false;
            }
        }
    }

    private static void writeParameters(List<CharSequence> parameters, ByteBuf out) {
        if (parameters.isEmpty()) {
            return;
        }
        out.writeByte(SP);
        if (parameters instanceof RandomAccess) {
            final int sizeMinusOne = parameters.size() - 1;
            for (int i = 0; i < sizeMinusOne; i++) {
                ByteBufUtil.writeAscii(out, parameters.get(i));
                out.writeByte(SP);
            }
            ByteBufUtil.writeAscii(out, parameters.get(sizeMinusOne));
        } else {
            final Iterator<CharSequence> params = parameters.iterator();
            for (;;) {
                ByteBufUtil.writeAscii(out, params.next());
                if (params.hasNext()) {
                    out.writeByte(SP);
                } else {
                    break;
                }
            }
        }
    }
}

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