当您将 HTTP URI 调用从 direct:parent 传播到 direct:a 但在 direct:parent 中维护嵌套异常子句时，direct:a 中引发的异常不会向上传播到父级路线。但是，您应该将嵌套异常子句重构为全局异常子句。
我创建了一个简单的测试用例，它可以模拟 204 消息上引发的异常，也可以调用真实服务并在 204 响应的情况下失败：
import org.apache.camel.Produce;
import org.apache.camel.ProducerTemplate;
import org.apache.camel.builder.AdviceWithRouteBuilder;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.http.common.HttpOperationFailedException;
import org.apache.camel.test.junit4.CamelTestSupport;
import org.junit.Test;
import java.util.HashMap;
import java.util.Map;
import static org.hamcrest.CoreMatchers.equalTo;
import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.CoreMatchers.nullValue;
public class Http4ExceptionHandlingTest extends CamelTestSupport {
@Produce(uri = "direct:parent")
protected ProducerTemplate template;
@Override
public boolean isUseAdviceWith() {
return true;
}
@Override
protected RouteBuilder createRouteBuilder() {
return new RouteBuilder() {
@Override
public void configure() throws Exception {
onException(HttpOperationFailedException.class)
.onWhen(exchange -> {
HttpOperationFailedException
exe = exchange.getException(HttpOperationFailedException.class);
return 204 == exe.getStatusCode();
})
.log("HTTP exception handled")
.handled(true)
//.continued(true)
.setBody(constant(null));
from("direct:parent").routeId("parent")
// .onException(HttpOperationFailedException.class)
// .onWhen(exchange -> {
// HttpOperationFailedException
// exe = exchange.getException(HttpOperationFailedException.class);
// return 204 == exe.getStatusCode();
// })
// .setBody(constant(null))
// .end()
.log("Parent start");
.to("direct:a")
.log("Parent done");
from("direct:a").routeId("a")
.log("a start")
.to("http4://localhost:8022/test/service?okStatusCodeRange=200-201")
.convertBodyTo(String.class)
.log("a done");
}
};
}
@Test
public void testExceptionHandling() throws Exception {
// comment the following line out if you want to invoke the real service instead!
weaveRoute();
context.start();
Object response = template.requestBody("foo");
assertThat(response, is(nullValue()));
}
@Test
public void testSuccessfulResponse() throws Exception {
// comment the following line out if you want to invoke the real service instead!
weaveRoute();
context.start();
Object response = template.requestBody("bar");
assertThat(response, is(equalTo("bar")));
}
private void weaveRoute() throws Exception {
context.getRouteDefinition("a").adviceWith(context, new AdviceWithRouteBuilder() {
@Override
public void configure() throws Exception {
this.interceptSendToEndpoint("http4*")
.skipSendToOriginalEndpoint()
.process(exchange -> {
String body = exchange.getIn().getBody(String.class);
if ("foo".equals(body)) {
Map<String, String> headers = new HashMap<>();
String location = "";
HttpOperationFailedException exe =
new HttpOperationFailedException("http://bla", 204, "No Content", location,
headers, "response body");
throw exe;
}
});
}
});
}
}
我已将原始嵌套异常子句留在父路由中，以便您比较结果。全局异常处理程序获得了一个额外的 .handled(true)` 语句，它刚刚脱离了当前路由。因此，该文档声明如下：
如果handled为真，那么抛出的异常会被处理，Camel不会在原来的路由中继续路由，而是爆发。但是，您可以在 onException 中配置一个路由，该路由将被使用。如果您需要创建一些自定义响应消息返回给调用者，或者因为抛出异常而进行任何其他处理，您可以使用此路由。 (Source)
不将捕获的异常设置为.handled(true) 实际上会导致堆栈跟踪的呈现，而不是继续执行。
我添加了更多日志语句以可视化异常处理中的行为。执行上面的代码，你会得到如下输出：
[INFO ] - - Parent start [ ] [parent] [ ] [main]
[INFO ] - - a start [ ] [a] [ ] [main]
[INFO ] - - HTTP exception handled [ ] [a] [ ] [main]
除了.handled(true)，您还可以使用.continued(true) 来继续执行记录：
如果 continue 为真，那么 Camel 将捕获异常，实际上只是忽略它并继续在原始路由中路由。但是，如果您在 onException 中配置了路由，它将首先路由该路由，然后再继续在原始路由中路由。
在全局异常子句中使用启用的.continued(true) 和禁用的.handled(true) 运行测试将产生以下日志：
[INFO ] - - Parent start [ ] [parent] [ ] [main]
[INFO ] - - a start [ ] [a] [ ] [main]
[INFO ] - - HTTP exception handled [ ] [a] [ ] [main]
[ERROR] - - Failed delivery for (MessageId: ...). Exhausted after delivery attempt: 1 caught: null. Handled and continue routing.
Message History
---------------------------------------------------------------------------------------------------------------------------------------
RouteId ProcessorId Processor Elapsed (ms)
[parent ] [parent ] [direct://parent ] [ 8]
[parent ] [log9 ] [log ] [ 0]
[parent ] [to4 ] [direct:a ] [ 8]
[a ] [log7 ] [log ] [ 1]
[a ] [to3 ] [http4://localhost:8022/test/service?okStatusCodeRange=200-201 ] [ 8]
[ ] [process2 ] [Processor@0x3c7f66c4 ] [ 8]
[a ] [log6 ] [log ] [ 1]
[a ] [setBody2 ] [setBody[{null}] ] [ 0]
Stacktrace
--------------------------------------------------------------------------------------------------------------------------------------- [ ] [o.a.c.p.DefaultErrorHandler] [ ] [main]
org.apache.camel.http.common.HttpOperationFailedException: HTTP operation failed invoking http://bla with statusCode: 204, redirectLocation:
at at.erpel.messaginghub.services.unit.routes.rest.Http4ExceptionHandlingTest$2.lambda$configure$1(Http4ExceptionHandlingTest.java:103)
at org.apache.camel.processor.DelegateSyncProcessor.process(DelegateSyncProcessor.java:63)
...
[INFO ] - - a done [ ] [a] [ ] [main]
[INFO ] - - Parent done [ ] [parent] [ ] [main]
从简化日志中可以看出，.continued(true) 不会跳出路由，但会记录消息历史记录以及被忽略异常的堆栈跟踪。
如果父路由中存在嵌套异常子句，而子路由确实遇到异常，则在嵌套异常子句中添加 .handled(true) 或 .continuted(true) 无效，因为子路由中捕获的实际异常是没有传播到父嵌套异常子句，因此根本没有处理。
我已经针对模拟和真实服务测试了代码示例，该服务在接收到foo 正文时返回204 响应，在接收到其他任何内容时返回200 响应。因此，?okStatusCodeRange=200-201 配置参数在我的情况下按预期工作。为了完整性：我使用的是 Camel 2.17.0。