使用ASM的一個類的所有超類java java字節碼代碼

Question

如何獲得一個類的所有超類使用ASM java字節碼？

Answer 1

這樣做的一個簡單方法是訪問類的構造函數的字節碼並記錄第一個構造函數調用指令，即調用您可以找到的invokespecial。這應該會給你當前感興趣的課程名稱super。

Answer 2

這有點棘手，因爲類文件只包含直接的超類。因此，你必須遞歸讀取所有的超類。

您可以通過使用帶有重寫訪問（int版本，int訪問，字符串名稱，字符串簽名，String superName，String [] interfaces）方法來讀取超類名稱的ClassVisitor來處理每個類。

僞代碼：

List<String> getSuperClasses(className){ 
    superClass=getSuperClass(className) 
    return superClass+getSuperClasses(superClass) 
} 

String getSuperClass(className) { 
    cw=new ClassWriter() 
    v=new SuperClassReadingClassVisitor(cw) 
    new ClassReader(className).accept(v) 
    return v.superClass 
} 

class SuperClassReadingClassVisitor{ 
    String superClass 
    @Override 
    visit(int version, int access, String name, String signature, String superName, String[] interfaces) { 
    superClass=superName 
    super.visit(version, access, name, ...) 
} 

Answer 3

package com.eg.agent; 

import java.lang.instrument.ClassFileTransformer; 
import java.lang.instrument.IllegalClassFormatException; 
import java.lang.instrument.Instrumentation; 
import java.security.ProtectionDomain; 

import java.io.IOException; 
import java.io.InputStream; 
import java.util.ArrayList; 

import org.objectweb.asm.ClassReader; 

public class EgClassFileTransformer implements ClassFileTransformer { 

    protected String agentArgString = ""; 
    protected Instrumentation instrumentation; 

    public EgClassFileTransformer(String agentArgs, Instrumentation inst){ 
     agentArgString = agentArgs; 
     instrumentation = inst; 
     instrumentation.addTransformer(this); 
    } 

    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, 
      ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException 
     { 
      //System.out.println("ClassName :"+className); 
      InputStream in = loader.getResourceAsStream(className.replace('.', '/') + ".class"); 
      try{ 
       ClassReader classReader=new ClassReader(in); 
       String superClassName = classReader.getSuperName(); 
       String[] interfaces = classReader.getInterfaces(); 
       if(interfaces!=null && interfaces.length > 0){ 
        for(int k=0;k<interfaces.length;k++){ 
         String inface = interfaces[k]; 
         System.out.println(" \t interface :"+inface); 
        } 
       } 
       //System.out.println("superClassName :"+superClassName); 
       ArrayList thisList = new ArrayList(); 
       thisList.add(superClassName); 
       ArrayList superList = printSuperClassNames(superClassName , thisList); 
       System.out.println("className :"+className +" ==>"+ " superList :"+superList); 
      } catch (IOException e) { 
       //e.printStackTrace(); 
       System.out.println("[EXECEPTION] ..."+className); 
      } 
      return null; 
     } 

    public static ArrayList printSuperClassNames(String className, ArrayList list) 
    { 
     ClassReader cr=null; 
     try { 
      cr = new ClassReader(className); 
     } catch (IOException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
     String superName = cr.getSuperName(); 
     //System.out.println("[superName]"+superName); 
     if(superName!=null && !superName.equals("java/lang/Object")) 
     { 
      list.add(superName); 
      String superClass = superName.replace('.', '/'); 
      printSuperClassNames(superClass, list); 
     } 
     return list; 
    } 
}