Dependency the toolkit, such as using maven or gradle

Dependency the toolkit, such as using maven or gradle

   <dependency>
      <groupId>org.apache.skywalking</groupId>
      <artifactId>apm-toolkit-trace</artifactId>
      <version>${skywalking.version}</version>
   </dependency>

Use TraceContext.traceId() API to obtain traceId.

import TraceContext;
...

modelAndView.addObject("traceId", TraceContext.traceId());

Use TraceContext.segmentId() API to obtain segmentId.

import TraceContext;
...

modelAndView.addObject("segmentId", TraceContext.segmentId());

Use TraceContext.spanId() API to obtain spanId.

import TraceContext;
...

modelAndView.addObject("spanId", TraceContext.spanId());

Sample codes only

Add @Trace to any method you want to trace. After that, you can see the span in the Stack.
Methods annotated with @Tag will try to tag the current active span with the given key (Tag#key()) and (Tag#value()), if there is no active span at all, this annotation takes no effect. @Tag can be repeated, and can be used in companion with @Trace, see examples below. The value of Tag is the same as what are supported in Customize Enhance Trace.
Add custom tag in the context of traced method, ActiveSpan.tag("key", "val").
ActiveSpan.error() Mark the current span as error status.
ActiveSpan.error(String errorMsg) Mark the current span as error status with a message.
ActiveSpan.error(Throwable throwable) Mark the current span as error status with a Throwable.
ActiveSpan.debug(String debugMsg) Add a debug level log message in the current span.
ActiveSpan.info(String infoMsg) Add an info level log message in the current span.
ActiveSpan.setOperationName(String operationName) Customize an operation name.

ActiveSpan.tag("my_tag", "my_value");
ActiveSpan.error();
ActiveSpan.error("Test-Error-Reason");

ActiveSpan.error(new RuntimeException("Test-Error-Throwable"));
ActiveSpan.info("Test-Info-Msg");
ActiveSpan.debug("Test-debug-Msg");

/**
 * The codes below will generate a span,
 * and two types of tags, 
      one type tag: keys are `tag1` and `tag2`, values are the passed-in parameters, respectively, 
      the other type tag: keys are `username`  and `age`, values are the return value in User, respectively
 */
@Trace
@Tag(key = "tag1", value = "arg[0]")
@Tag(key = "tag2", value = "arg[1]")
@Tag(key = "username", value = "returnedObj.username")
@Tag(key = "age", value = "returnedObj.age")
public User methodYouWantToTrace(String param1, String param2) {
    // ActiveSpan.setOperationName("Customize your own operation name, if this is an entry span, this would be an endpoint name");
    // ...
}

Use TraceContext.putCorrelation() API to put custom data in tracing context.

Optional<String> previous = TraceContext.putCorrelation("customKey", "customValue");

CorrelationContext will remove the item when the value is null or empty.

Use TraceContext.getCorrelation() API to get custom data.

Optional<String> value = TraceContext.getCorrelation("customKey");

CorrelationContext configuration descriptions could be found in the agent configuration documentation, with correlation. as the prefix.

skywalking-java