How to display reflection frame of StackFrame in Java 9?-javaTutorial-php.cn

How to display reflection frame of StackFrame in Java 9?

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Release： 2023-09-04 17:09:03

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如何在Java 9中显示StackFrame的反射框架？

A standard API is provided in Java 9, using the java.lang.StackWalker class. This class is designed to be efficient, by allowing delayed access to stack frames. Additionally, there are several options to include implementation and/or reflection frames in the stack trace, which can be useful for debugging purposes. For example, we add the SHOW_REFLECT_FRAMES option when creating a StackWalker instance in order to print the frames of the reflection method.

In the following example, we can display the reflection frame of the StackFrame

Example

import java.lang.StackWalker.Option;
import java.lang.StackWalker.StackFrame;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.List;
import java.util.stream.Collectors;

public class ReflectionFrameTest {
   public static void main(String args[]) throws NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
      <strong>Method </strong>test1Method = Test1.class.<strong>getDeclaredMethod</strong>("test1", (Class<!--?-->[]) null);
      test1Method.<strong>invoke</strong>(null, (Object[]) null);
   }
}
class Test1 {
   protected static void test1() {
      Test2.test2();
   }
}
class Test2 {
   protected static void test2() {
      <strong>// show reflection methods</strong>
      <strong>List<StackFrame></strong> stack = <strong>StackWalker.getInstance</strong>(Option.<strong>SHOW_REFLECT_FRAMES</strong>).walk((s) -> s.collect(Collectors.toList()));
      for(<strong>StackFrame </strong>frame : stack) {
         System.out.println(frame.<strong>getClassName()</strong> + " " + frame.<strong>getLineNumber()</strong> + " " + frame.<strong>getMethodName()</strong>);
      }
   }
}

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Output

<strong>Test2 22 test2
Test1 16 test1
jdk.internal.reflect.NativeMethodAccessorImpl -2 invoke0
jdk.internal.reflect.NativeMethodAccessorImpl 62 invoke
jdk.internal.reflect.DelegatingMethodAccessorImpl 43 invoke
java.lang.reflect.Method 564 invoke
ReflectionFrameTest 11 main</strong>

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