Javassist读取类信息非常简单，使用ClassPool对象获取到CtClass对象后就可以像使用Java反射API一样去读取类信息了。
    Javassist读取类信息示例代码：

    1. package com.anbai.sec.bytecode.javassist;
    3. import javassist.*;
    5. import java.util.Arrays;
    7. public class JavassistClassAccessTest {
    9.   public static void main(String[] args) {
    10.     // 创建ClassPool对象
    11.     ClassPool classPool = ClassPool.getDefault();
    13.     try {
    14.       CtClass ctClass = classPool.get("com.anbai.sec.bytecode.TestHelloWorld");
    16.       System.out.println(
    17.           "解析类名：" + ctClass.getName() + "，父类：" + ctClass.getSuperclass().getName() +
    18.               "，实现接口：" + Arrays.toString(ctClass.getInterfaces())
    19.       );
    21.       System.out.println("-----------------------------------------------------------------------------");
    23.       // 获取所有的构造方法
    24.       CtConstructor[] ctConstructors = ctClass.getDeclaredConstructors();
    26.       // 获取所有的成员变量
    27.       CtField[] ctFields = ctClass.getDeclaredFields();
    29.       // 获取所有的成员方法
    30.       CtMethod[] ctMethods = ctClass.getDeclaredMethods();
    32.       // 输出所有的构造方法
    33.       for (CtConstructor ctConstructor : ctConstructors) {
    34.         System.out.println(ctConstructor.getMethodInfo());
    35.       }
    37.       System.out.println("-----------------------------------------------------------------------------");
    39.       // 输出所有成员变量
    40.       for (CtField ctField : ctFields) {
    41.         System.out.println(ctField);
    42.       }
    44.       System.out.println("-----------------------------------------------------------------------------");
    46.       // 输出所有的成员方法
    47.       for (CtMethod ctMethod : ctMethods) {
    48.         System.out.println(ctMethod);
    49.       }
    50.     } catch (NotFoundException e) {
    51.       e.printStackTrace();
    52.     }
    53.   }
    55. }

    程序执行结果：

    1. 解析类名：com.anbai.sec.bytecode.TestHelloWorld，父类：java.lang.Object，实现接口：[javassist.CtClassType@60addb54[public abstract interface class java.io.Serializable fields= constructors= methods=]]
    2. -----------------------------------------------------------------------------
    3. <init> ()V
    4. -----------------------------------------------------------------------------
    5. com.anbai.sec.bytecode.TestHelloWorld.serialVersionUID:J
    6. com.anbai.sec.bytecode.TestHelloWorld.id:J
    7. com.anbai.sec.bytecode.TestHelloWorld.username:Ljava/lang/String;
    8. com.anbai.sec.bytecode.TestHelloWorld.password:Ljava/lang/String;
    9. -----------------------------------------------------------------------------
    10. javassist.CtMethod@ca717109[public hello (Ljava/lang/String;)Ljava/lang/String;]
    11. javassist.CtMethod@44a4fe33[public static main ([Ljava/lang/String;)V]
    12. javassist.CtMethod@fb809fd2[public getId ()J]
    13. javassist.CtMethod@5321790a[public setId (J)V]
    14. javassist.CtMethod@7a2b684d[public getUsername ()Ljava/lang/String;]
    15. javassist.CtMethod@7942008f[public setUsername (Ljava/lang/String;)V]
    16. javassist.CtMethod@3b463cd2[public getPassword ()Ljava/lang/String;]
    17. javassist.CtMethod@da549dd4[public setPassword (Ljava/lang/String;)V]
    18. javassist.CtMethod@69cb6c6d[public toString ()Ljava/lang/String;]