我是 Netty 新手,仍在努力寻找自己的方法。我正在寻找创建一个异步工作的 http 客户端。
http的netty例子只展示了如何等待IO操作,并没有展示如何使用添加监听器,所以最近几天我一直在努力解决这个问题。
我正在尝试创建一个请求类,它将处理请求的所有不同状态,从连接、发送数据、处理响应,然后关闭连接。
为了做到这一点,我的课程延长了SimpleChannelUpstreamHandler并实施ChannelFutureListener。我用一个ChannelPipelineFactory它将(this)实例添加到类(作为SimpleChannelUpstreamHandler) 作为处理程序添加到管道。
连接是这样创建的:
this.state = State.Connecting;
this.clientBootstrap.connect(this.address).addListener(this);
然后操作完成 method:
@Override
public void operationComplete(ChannelFuture future) throws Exception {
State oldState = this.state;
if (!future.isSuccess()) {
this.status = Status.Failed;
future.getChannel().disconnect().addListener(this);
}
else if (future.isCancelled()) {
this.status = Status.Canceled;
future.getChannel().disconnect().addListener(this);
}
else switch (this.state) {
case Connecting:
this.state = State.Sending;
Channel channel = future.getChannel();
channel.write(this.createRequest()).addListener(this);
break;
case Sending:
this.state = State.Disconnecting;
future.getChannel().disconnect().addListener(this);
break;
case Disconnecting:
this.state = State.Closing;
future.getChannel().close().addListener(this);
break;
case Closing:
this.state = State.Finished;
break;
}
System.out.println("request operationComplete start state: " + oldState + ", end state: " + this.state + ", status: " + this.status);
}
private HttpRequest createRequest() {
String url = this.url.toString();
HttpRequest request = new DefaultHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.GET, url);
request.setHeader(HttpHeaders.Names.HOST, this.url.getHost());
request.setHeader(HttpHeaders.Names.CONNECTION, HttpHeaders.Values.CLOSE);
request.setHeader(HttpHeaders.Names.ACCEPT_ENCODING, HttpHeaders.Values.GZIP);
return request;
}
该类还覆盖了收到消息 method:
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
System.out.println("messageReceived");
HttpResponse response = (HttpResponse) e.getMessage();
ChannelBuffer content = response.getContent();
if (content.readable()) {
System.out.println("CONTENT: " + content.toString(CharsetUtil.UTF_8));
}
}
问题是我得到这个输出:
request operationComplete start state: Connecting, end state: Sending, status: Unknown
request operationComplete start state: Sending, end state: Disconnecting, status: Unknown
request operationComplete start state: Closing, end state: Finished, status: Unknown
request operationComplete start state: Disconnecting, end state: Finished, status: Unknown
正如你所看到的收到消息由于某种原因,即使管道工厂将此类的实例添加到管道中,也不会执行该类的实例。
我在这里缺少什么想法吗?
谢谢。
Edit
感谢 @JestanNirojan 的帮助,我终于成功完成了这项工作,以防有人对解决方案感兴趣:
public class ClientRequest extends SimpleChannelUpstreamHandler {
....
public void connect() {
this.state = State.Connecting;
System.out.println(this.state);
this.clientBootstrap.connect(this.address);
}
@Override
public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
this.state = State.Sending;
System.out.println(this.state);
ctx.getChannel().write(this.createRequest());
}
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
HttpResponse response = (HttpResponse) e.getMessage();
ChannelBuffer content = response.getContent();
if (content.readable()) {
System.out.println("CONTENT: " + content.toString(CharsetUtil.UTF_8));
}
this.state = State.Disconnecting;
System.out.println(this.state);
}
@Override
public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
this.state = State.Closing;
System.out.println(this.state);
}
@Override
public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
this.state = State.Finished;
System.out.println(this.state);
}
private HttpRequest createRequest() {
String url = this.url.toString();
HttpRequest request = new DefaultHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.GET, url);
request.setHeader(HttpHeaders.Names.HOST, this.url.getHost());
request.setHeader(HttpHeaders.Names.CONNECTION, HttpHeaders.Values.CLOSE);
request.setHeader(HttpHeaders.Names.ACCEPT_ENCODING, HttpHeaders.Values.GZIP);
return request;
}
}