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本文主要研究一下dubbo的ConsumerContextFilter

ConsumerContextFilter

dubbo-2.7.2/dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/filter/ConsumerContextFilter.java

@Activate(group = CONSUMER, order = -10000)public class ConsumerContextFilter extends ListenableFilter {    public ConsumerContextFilter() {        super.listener = new ConsumerContextListener();    }    @Override    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {        RpcContext.getContext()                .setInvoker(invoker)                .setInvocation(invocation)                .setLocalAddress(NetUtils.getLocalHost(), 0)                .setRemoteAddress(invoker.getUrl().getHost(),                        invoker.getUrl().getPort());        if (invocation instanceof RpcInvocation) {            ((RpcInvocation) invocation).setInvoker(invoker);        }        try {            RpcContext.removeServerContext();            return invoker.invoke(invocation);        } finally {            RpcContext.removeContext();        }    }    static class ConsumerContextListener implements Listener {        @Override        public void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {            RpcContext.getServerContext().setAttachments(appResponse.getAttachments());        }        @Override        public void onError(Throwable t, Invoker<?> invoker, Invocation invocation) {        }    }}
  • ConsumerContextFilter继承了ListenableFilter，其invoke方法在invoke之前会给RpcContext.getContext()设置invoker、invocation、localAddress、remoteAddress并移除serverContext；在invoke之后移除当前context；其listener为ConsumerContextListener，在onResponse的时候，会给RpcContext.getServerContext()设置attachments

实例

dubbo-2.7.2/dubbo-rpc/dubbo-rpc-api/src/test/java/org/apache/dubbo/rpc/filter/ConsumerContextFilterTest.java

public class ConsumerContextFilterTest {    Filter consumerContextFilter = new ConsumerContextFilter();    @Test    public void testSetContext() {        URL url = URL.valueOf("test://test:11/test?group=dubbo&version=1.1");        Invoker<DemoService> invoker = new MyInvoker<DemoService>(url);        Invocation invocation = new MockInvocation();        Result asyncResult = consumerContextFilter.invoke(invoker, invocation);        asyncResult.thenApplyWithContext(result -> {            assertEquals(invoker, RpcContext.getContext().getInvoker());            assertEquals(invocation, RpcContext.getContext().getInvocation());            assertEquals(NetUtils.getLocalHost() + ":0", RpcContext.getContext().getLocalAddressString());            assertEquals("test:11", RpcContext.getContext().getRemoteAddressString());            return result;        });    }}
  • 这里使用asyncResult.thenApplyWithContext来验证一下RpcContext.getContext()的invoker、invocation、localhost、remoteAddress值

小结

ConsumerContextFilter继承了ListenableFilter，其invoke方法在invoke之前会给RpcContext.getContext()设置invoker、invocation、localAddress、remoteAddress并移除serverContext；在invoke之后移除当前context；其listener为ConsumerContextListener，在onResponse的时候，会给RpcContext.getServerContext()设置attachments

doc

  • ConsumerContextFilter