java - 使用 Java 反射测试空方法体

Question

正如标题所暗示的，有什么方法可以使用反射来查看一个方法是否有空体？

Answer 1

仔细一想，我不这么认为。你可以看看 BCEL虽然……

The Byte Code Engineering Library is intended to give users a convenient possibility to analyze, create, and manipulate (binary) Java class files

这里有一个片段可以让你从这个 article 开始...

public class ClassViewer{
   private JavaClass clazz;
   public ClassViewer(String clazz){
      this.clazz = Repository.lookupClass(clazz);
    }
   public static void main(String args[]){
      if(args.length != 1)
        throw new IllegalArgumentException(
          "One and only one class at a time!");
      ClassViewer viewer = new ClassViewer(args[0]);
      viewer.start();
    }
   private void start(){
      if(this.clazz != null){
        // first print the structure 
        // of the class file
        System.err.println(clazz);
        // next print the methods
        Method[] methods = clazz.getMethods();
       for(int i=0; i<methods.length; i++){
          System.err.println(methods[i]);
          // now print the actual
          // byte code for each method
          Code code = methods[i].getCode();
         if(code != null)
            System.err.println(code);
       }
     }else
        throw new RuntimeException(
          "Class file is null!");
    }
}