net.bytebuddy.asm

Annotation Type Advice.OnMethodEnter

@Documented
 @Retention(value=RUNTIME)
 @Target(value=METHOD)
public static @interface Advice.OnMethodEnter

Indicates that this method should be inlined before the matched method is invoked. Any class must declare at most one method with this annotation. The annotated method must be static. When instrumenting constructors, the this values can only be accessed for writing fields but not for reading fields or invoking methods.

The annotated method can return a value that is made accessible to another method annotated by Advice.OnMethodExit.

See Also:

Advice, Advice.Argument, Advice.This

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
boolean	inline Determines if the annotated method should be inlined into the instrumented method or invoked from it.
boolean	prependLineNumber If set to true, the instrumented method's line number information is adjusted such that stack traces generated within this advice method appear as if they were generated within the first line of the instrumented method.
Class<?>	skipOn Setting any non-primitive type allows to specify that the instrumented method should not be invoked if a instanceof check of the return value of this advice method is returned.
Class<? extends Throwable>	suppress Indicates that this advice should suppress any Throwable type being thrown during the advice's execution.

Element Detail

inline

public abstract boolean inline

Determines if the annotated method should be inlined into the instrumented method or invoked from it. When a method is inlined, its byte code is copied into the body of the target method. this makes it is possible to execute code with the visibility privileges of the instrumented method while loosing the privileges of the declared method methods. When a method is not inlined, it is invoked similarly to a common Java method call. Note that it is not possible to set breakpoints within a method when it is inlined as no debugging information is copied from the advice method into the instrumented method.

Returns:

true if the annotated method should be inlined into the instrumented method.

Default:

true

suppress

public abstract Class<? extends Throwable> suppress

Indicates that this advice should suppress any Throwable type being thrown during the advice's execution.

Returns:

The type of Throwable to suppress.

Default:

net.bytebuddy.asm.Advice.NoExceptionHandler.class

skipOn

public abstract Class<?> skipOn

Setting any non-primitive type allows to specify that the instrumented method should not be invoked if a instanceof check of the return value of this advice method is returned. It is not allowed to specify a primitive type whereas specifying void indicates that the instrumented method should never be skipped. This is the default behavior. Finally, it is possible to set this property to Advice.DefaultValueOrTrue where the instrumented method is not invoked if this advice method returns the return type's default value, i.e. 0 for primitive types or null for reference types. For a boolean method, a return value of true indicates to skip the instrumented method.

Returns:

void if the instrumented method should never be skipped, Advice.DefaultValueOrTrue or any non-primitive type if the instrumented method should be skipped upon returning any instance of the specified type.

Default:

void.class

prependLineNumber

public abstract boolean prependLineNumber

If set to true, the instrumented method's line number information is adjusted such that stack traces generated within this advice method appear as if they were generated within the first line of the instrumented method. If set to false, no line number information is made available for such stack traces.

Returns:

true if this advice code should appear as if it was added within the first line of the instrumented method.

Default:

true