首先，需要在pom.xml文件中添加
Netty和
Spring Boot的依赖：
```xml
<dependency>
<groupId>io.
netty</groupId>
<artifactId>
netty-all</artifactId>
<version>4.1.43.Final</version>
</dependency>
<dependency>
<groupId>org.
springframework.boot</groupId>
<artifactId>
spring-boot-starter-
websocket</artifactId>
</dependency>
```
然后，创建一个
WebSocket客户端类，继承自 `ChannelInboundHandlerAdapter`，实现
WebSocket协议相关的方法：
```
java
@Component
public class
WebSocketClient extends ChannelInboundHandlerAdapter {
private
WebSocketClientHandshaker handshaker;
private ChannelPromise handshakeFuture;
@Autowired
private
WebSocketClientHandler handler;
public void connect(String url) thro
ws Exception {
URI uri = new URI(url);
String scheme = uri.getScheme() == null ? "
ws" : uri.getScheme();
String host = uri.getHost() == null ? "127.0.0.1" : uri.getHost();
int port = uri.getPort();
if (port == -1) {
if ("
ws".equalsIgnoreCase(scheme)) {
port = 80;
} else if ("
wss".equalsIgnoreCase(scheme)) {
port = 443;
}
}
if (!"
ws".equalsIgnoreCase(scheme) && !"
wss".equalsIgnoreCase(scheme)) {
throw new IllegalArgumentException("Unsupported scheme: "
+ scheme);
}
final
WebSocketClientHandler handler = this.handler;
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(group)
.option(ChannelOption.SO_KEEPALIVE, true)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) thro
ws Exception {
ChannelPipeline pipeline = ch.pipeline();
if ("
wss".equalsIgnoreCase(scheme)) {
SslContext sslContext = SslContextBuilder.for
Client().build();
pipeline.addLast(sslContext.newHandler(ch.alloc(), host, port));
}
pipeline.addLast(new Http
ClientCodec(),
new HttpObjectAggregator(8192),
WebSocketClientCompressionHandler.INSTANCE,
handler);
}
});
Channel channel = bootstrap.connect(uri.getHost(), port).sync().channel();
handshaker =
WebSocketClientHandshakerFactory.newHandshaker(
uri,
WebSocketVersion.V13, null, true, new DefaultHttpHeaders());
handshakeFuture = channel.newPromise();
handler.setHandshakeFuture(handshakeFuture);
channel.writeAndFlush(new DefaultHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.GET, uri.getRawPath()))
.addListener(new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture future) {
if (future.isSuccess()) {
handshaker.handshake(future.channel());
} else {
handshakeFuture.setFailure(future.cause());
}
}
});
handshakeFuture.sync();
channel.closeFuture().sync();
} finally {
group.shutdownGracefully();
}
}
@Override
public void channelActive(ChannelHandlerContext ctx) thro
ws Exception {
handler.setCtx(ctx);
handshaker.handshake(ctx.channel());
}
@Override
public void channelInactive(ChannelHandlerContext ctx) thro
ws Exception {
System.out.println("
WebSocket Client disconnected!");
handler.setCtx(null);
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) thro
ws Exception {
Channel ch = ctx.channel();
if (!handshaker.isHandshakeComplete()) {
try {
handshaker.finishHandshake(ch, (FullHttpResponse) msg);
System.out.println("
WebSocket Client connected!");
handshakeFuture.setSuccess();
} catch (
WebSocketHandshakeException e) {
System.out.println("
WebSocket Client failed to connect");
handshakeFuture.setFailure(e);
}
return;
}
if (msg instanceof FullHttpResponse) {
FullHttpResponse response = (FullHttpResponse) msg;
throw new IllegalStateException(
"Unexpected FullHttpResponse (getStatus="
+ response.status()
+
", content="
+ response.content().toString(CharsetUtil.UTF_8)
+ ')');
}
WebSocketFrame frame = (
WebSocketFrame) msg;
if (frame instanceof Text
WebSocketFrame) {
Text
WebSocketFrame textFrame = (Text
WebSocketFrame) frame;
System.out.println("
WebSocket Client received message: "
+ textFrame.text());
} else if (frame instanceof Pong
WebSocketFrame) {
System.out.println("
WebSocket Client received pong");
} else if (frame instanceof Close
WebSocketFrame) {
System.out.println("
WebSocket Client received closing");
ch.close();
}
}
}
```
在这个类中，我们注入了一个 `
WebSocketClientHandler` 的实例，它也是一个 `ChannelInboundHandlerAdapter`，用于处理
WebSocket消息。在 `connect()` 方法中，我们使用
Netty创建了一个Bootstrap实例，并设置了一些参数，然后连接到
WebSocket服务器。在连接成功后，进行了握手操作，以确保连接正常建立。
下面是 `
WebSocketClientHandler` 的实现：
```
java
@Component
public class
WebSocketClientHandler extends ChannelInboundHandlerAdapter {
private ChannelHandlerContext ctx;
private ChannelPromise handshakeFuture;
public void setCtx(ChannelHandlerContext ctx) {
this.ctx = ctx;
}
public void setHandshakeFuture(ChannelPromise handshakeFuture) {
this.handshakeFuture = handshakeFuture;
}
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) thro
ws Exception {
if (evt ==
WebSocketClientProtocolHandler.
ClientHandshakeStateEvent.HANDSHAKE_COMPLETE) {
handshakeFuture.setSuccess();
} else {
super.userEventTriggered(ctx, evt);
}
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) thro
ws Exception {
// Handle
WebSocket message
}
// Other methods
}
```
在这个类中，我们重写了 `channelRead()` 方法，用于处理
WebSocket消息。我们也保存了当前的 `ChannelHandlerContext` 和握手操作的 `ChannelPromise`，以便在连接成功后进行操作。
最后，在
Spring Boot的主类中，可以通过注入 `
WebSocketClient` 的方式来启动
WebSocket客户端：
```
java
@
SpringBootApplication
public class Application {
@Autowired
private
WebSocketClient webSocketClient;
public static void main(String[] args) thro
ws Exception {
SpringApplication.run(Application.class, args);
}
@EventListener(ApplicationReadyEvent.class)
public void connect() thro
ws Exception {
webSocketClient.connect("
ws://localhost:8080/
websocket");
}
}
```
在 `connect()` 方法中，我们调用了 `
WebSocketClient` 的 `connect()` 方法，来连接到
WebSocket服务器。注意，这个方法是阻塞的，直到连接关闭或连接失败。
这样，我们就成功地使用
Netty和
Spring Boot实现了一个
WebSocket客户端，并且可以将其注入到
Spring Boot的Bean容器中，以方便管理和使用。
扫一扫
1086
被折叠的 条评论
为什么被折叠?
到【灌水乐园】发言
