这篇文章给大家介绍netty中EmbeddedChannel如何使用，内容非常详细，感兴趣的小伙伴们可以参考借鉴，希望对大家能有所帮助。
一种特殊的Channel实现----EmbeddedChannel，它是Netty专门为改进针对ChannelHandler的单元测试而提供的。
| 名称 | 职责 |
|---|---|
| writeInbound | 将入站消息写到EmbeddedChannel中。如果可以通过readInbound方法从EmbeddedChannel中读取数据，则返回true |
| readInbound | 从EmbeddedChannel中读取入站消息。任何返回东西都经过整个ChannelPipeline。如果没有任何可供读取的，则返回null |
| writeOutbound | 将出站消息写到EmbeddedChannel中，如果现在可以通过readOutbound从EmbeddedChannel中读取到东西，则返回true |
| readOutbound | 从EmbeddedChannel中读取出站消息。任何返回东西都经过整个ChannelPipeline。如果没有任何可供读取的，则返回null |
| finish | 将EmbeddedChannel标记为完成，如果有可读取的入站或出站数据，则返回true。这个方法还将会调用EmbeddedChannel上的close方法 |
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public class FixedLengthFrameDecoder extends ByteToMessageDecoder {
private final int frameLength;
public FixedLengthFrameDecoder(int frameLength) {
if (frameLength <= 0) {
throw new IllegalArgumentException("frameLength must be positive integer: " + frameLength);
}
this.frameLength = frameLength;
}
@Override
protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<object> out) throws Exception {
while (in.readableBytes() >= frameLength) {
ByteBuf buf = in.readBytes(frameLength);
out.add(buf);
}
}
}public class FixedLengthFrameDecoderTest {
@Test
public void testFramesDecoded() {
ByteBuf buf = Unpooled.buffer();
for (int i = 0; i < 9; i++) {
buf.writeByte(i);
}
ByteBuf input = buf.duplicate();
EmbeddedChannel channel = new EmbeddedChannel(new FixedLengthFrameDecoder(3));
Assert.assertTrue(channel.writeInbound(input.retain()));
Assert.assertTrue(channel.finish());
ByteBuf read = channel.readInbound();
Assert.assertEquals(buf.readSlice(3), read);
read.release();
read = channel.readInbound();
Assert.assertEquals(buf.readSlice(3), read);
read.release();
read = channel.readInbound();
Assert.assertEquals(buf.readSlice(3), read);
read.release();
Assert.assertNull(channel.readInbound());
buf.release();
}
@Test
public void testFramesDecoded2() {
ByteBuf buf = Unpooled.buffer();
for (int i = 0; i < 9; i++) {
buf.writeByte(i);
}
ByteBuf input = buf.duplicate();
EmbeddedChannel channel = new EmbeddedChannel(new FixedLengthFrameDecoder(3));
Assert.assertFalse(channel.writeInbound(input.readBytes(2)));
Assert.assertTrue(channel.writeInbound(input.readBytes(7)));
Assert.assertTrue(channel.finish());
ByteBuf read = channel.readInbound();
Assert.assertEquals(buf.readSlice(3), read);
read.release();
read = channel.readInbound();
Assert.assertEquals(buf.readSlice(3), read);
read.release();
read = channel.readInbound();
Assert.assertEquals(buf.readSlice(3), read);
read.release();
Assert.assertNull(channel.readInbound());
buf.release();
}
}public class AbsIntegerEncoder extends MessageToMessageEncoder<bytebuf> {
@Override
protected void encode(ChannelHandlerContext channelHandlerContext, ByteBuf in, List<object> out) throws Exception {
while (in.readableBytes() >= 4) {
int value = Math.abs(in.readInt());
out.add(value);
}
}
}public class AbsIntegerEncoderTest {
@Test
public void testEncoded() {
ByteBuf buf = Unpooled.buffer();
for (int i = 0; i < 10; i++) {
buf.writeInt(i * -1);
}
EmbeddedChannel channel = new EmbeddedChannel(new AbsIntegerEncoder());
Assert.assertTrue(channel.writeOutbound(buf));
Assert.assertTrue(channel.finish());
for (int i = 0; i < 10; i++) {
Assert.assertEquals(Integer.valueOf(i), channel.readOutbound());
}
Assert.assertNull(channel.readOutbound());
}
}public class FrameChunkDecoder extends ByteToMessageDecoder {
private final int maxFrameSize;
public FrameChunkDecoder(int maxFrameSize) {
this.maxFrameSize = maxFrameSize;
}
@Override
protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<object> out) throws Exception {
int readableBytes = in.readableBytes();
if (readableBytes > maxFrameSize) {
in.clear();
throw new TooLongFrameException();
}
ByteBuf buf = in.readBytes(readableBytes);
out.add(buf);
}
}public class FrameChunkDecoderTest {
@Test
public void testFramesDecoded() {
ByteBuf buf = Unpooled.buffer();
for (int i = 0; i < 9; i++) {
buf.writeByte(i);
}
ByteBuf input = buf.duplicate();
EmbeddedChannel channel = new EmbeddedChannel(new FrameChunkDecoder(3));
Assert.assertTrue(channel.writeInbound(input.readBytes(2)));
try {
channel.writeInbound(input.readBytes(4));
Assert.fail();
} catch (TooLongFrameException e) {
}
Assert.assertTrue(channel.writeInbound(input.readBytes(3)));
Assert.assertTrue(channel.finish());
ByteBuf read = channel.readInbound();
Assert.assertEquals(buf.readSlice(2), read);
read.release();
read = channel.readInbound();
Assert.assertEquals(buf.skipBytes(4).readSlice(3), read);
read.release();
buf.release();
}
}关于netty中EmbeddedChannel如何使用就分享到这里了，希望以上内容可以对大家有一定的帮助，可以学到更多知识。如果觉得文章不错，可以把它分享出去让更多的人看到。
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原文链接：https://my.oschina.net/u/4176467/blog/3082428
