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再探 JDK Proxy ASM 字节码

原创 数据库开发技术 作者：DevXTalk 时间：2023-02-03 22:29:03 0 删除 编辑

再探 JDK Proxy ASM 字节码

上期内容 JDK Proxy 生成的代理对象源码 探究了JDK 动态代理生成的代理对象 java 源代码，本期内容继续探究 JDK 动态代理使用 ASM 技术生成的字节码.

使用 jdk 动态代理创建代理对象 

public class JdkProxyDemo {

    interface Foo {
        void foo();
    }

    static final class Target implements Foo {
        @Override
        public void foo() {
            System.out.println("Target foo");
        }
    }

    public static void main(String[] args) throws Exception {

        Target target = new Target();

        Foo proxy = (Foo) Proxy.newProxyInstance(JdkProxyDemo.class.getClassLoader(), new Class[]{Foo.class}, new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                System.out.println("before --------------------------------");
                Object ret = method.invoke(target, args);
                System.out.println("after --------------------------------");
                return ret;
            }
        });

        System.out.println(proxy.getClass());

        proxy.foo();

        System.in.read();
    }
}

jdk 动态代理生成代理类源码 

package org.devx.spring.certified.professional.edu.course.a12;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.UndeclaredThrowableException;
import org.devx.spring.certified.professional.edu.course.a12.JdkProxyDemo;

final class $Proxy0
        extends Proxy
        implements JdkProxyDemo.Foo {
    private static Method m1;
    private static Method m2;
    private static Method m3;
    private static Method m0;

    public $Proxy0(InvocationHandler invocationHandler) {
        super(invocationHandler);
    }

    public final boolean equals(Object object) {
        try {
            return (Boolean)this.h.invoke(this, m1, new Object[]{object});
        }
        catch (Error | RuntimeException throwable) {
            throw throwable;
        }
        catch (Throwable throwable) {
            throw new UndeclaredThrowableException(throwable);
        }
    }

    public final String toString() {
        try {
            return (String)this.h.invoke(this, m2, null);
        }
        catch (Error | RuntimeException throwable) {
            throw throwable;
        }
        catch (Throwable throwable) {
            throw new UndeclaredThrowableException(throwable);
        }
    }

    public final void foo() {
        try {
            this.h.invoke(this, m3, null);
            return;
        }
        catch (Error | RuntimeException throwable) {
            throw throwable;
        }
        catch (Throwable throwable) {
            throw new UndeclaredThrowableException(throwable);
        }
    }

    public final int hashCode() {
        try {
            return (Integer)this.h.invoke(this, m0, null);
        }
        catch (Error | RuntimeException throwable) {
            throw throwable;
        }
        catch (Throwable throwable) {
            throw new UndeclaredThrowableException(throwable);
        }
    }

    static {
        try {
            m1 = Class.forName("java.lang.Object").getMethod("equals", Class.forName("java.lang.Object"));
            m2 = Class.forName("java.lang.Object").getMethod("toString", new Class[0]);
            m3 = Class.forName("org.devx.spring.certified.professional.edu.course.a12.JdkProxyDemo$Foo").getMethod("foo", new Class[0]);
            m0 = Class.forName("java.lang.Object").getMethod("hashCode", new Class[0]);
        }
        catch (NoSuchMethodException noSuchMethodException) {
            throw new NoSuchMethodError(noSuchMethodException.getMessage());
        }
        catch (ClassNotFoundException classNotFoundException) {
            throw new NoClassDefFoundError(classNotFoundException.getMessage());
        }
    }
}

ASM Bytecode Outline 插件

在 idea 中安装 ASM Bytecode Outline 插件,将生成的代理类源码拷贝为 .java 源文件，使用ASM Bytecode Outline 查看 ASM 生成的字节码。

ASM 生成的代理对象字节码

该代码由 ASM Bytecode Outline 插件提供.

// class version 52.0 (52)
// access flags 0x30
final class org/devx/spring/certified/professional/edu/course/a12/$Proxy0 extends java/lang/reflect/Proxy  implements org/devx/spring/certified/professional/edu/course/a12/JdkProxyDemo$Foo  {

  // compiled from: $Proxy0.java
  // access flags 0x608
  static abstract INNERCLASS org/devx/spring/certified/professional/edu/course/a12/JdkProxyDemo$Foo org/devx/spring/certified/professional/edu/course/a12/JdkProxyDemo Foo

  // access flags 0xA
  private static Ljava/lang/reflect/Method; m1

  // access flags 0xA
  private static Ljava/lang/reflect/Method; m2

  // access flags 0xA
  private static Ljava/lang/reflect/Method; m3

  // access flags 0xA
  private static Ljava/lang/reflect/Method; m0

  // access flags 0x8
  static <clinit>()V
    TRYCATCHBLOCK L0 L1 L2 java/lang/NoSuchMethodException
    TRYCATCHBLOCK L0 L1 L3 java/lang/ClassNotFoundException
   L0
    LINENUMBER 72 L0
    LDC "java.lang.Object"
    INVOKESTATIC java/lang/Class.forName (Ljava/lang/String;)Ljava/lang/Class;
    LDC "equals"
    ICONST_1
    ANEWARRAY java/lang/Class
    DUP
    ICONST_0
    LDC "java.lang.Object"
    INVOKESTATIC java/lang/Class.forName (Ljava/lang/String;)Ljava/lang/Class;
    AASTORE
    INVOKEVIRTUAL java/lang/Class.getMethod (Ljava/lang/String;[Ljava/lang/Class;)Ljava/lang/reflect/Method;
    PUTSTATIC org/devx/spring/certified/professional/edu/course/a12/$Proxy0.m1 : Ljava/lang/reflect/Method;
   L4
    LINENUMBER 73 L4
    LDC "java.lang.Object"
    INVOKESTATIC java/lang/Class.forName (Ljava/lang/String;)Ljava/lang/Class;
    LDC "toString"
    ICONST_0
    ANEWARRAY java/lang/Class
    INVOKEVIRTUAL java/lang/Class.getMethod (Ljava/lang/String;[Ljava/lang/Class;)Ljava/lang/reflect/Method;
    PUTSTATIC org/devx/spring/certified/professional/edu/course/a12/$Proxy0.m2 : Ljava/lang/reflect/Method;
   L5
    LINENUMBER 74 L5
    LDC "org.devx.spring.certified.professional.edu.course.a12.JdkProxyDemo$Foo"
    INVOKESTATIC java/lang/Class.forName (Ljava/lang/String;)Ljava/lang/Class;
    LDC "foo"
    ICONST_0
    ANEWARRAY java/lang/Class
    INVOKEVIRTUAL java/lang/Class.getMethod (Ljava/lang/String;[Ljava/lang/Class;)Ljava/lang/reflect/Method;
    PUTSTATIC org/devx/spring/certified/professional/edu/course/a12/$Proxy0.m3 : Ljava/lang/reflect/Method;
   L6
    LINENUMBER 75 L6
    LDC "java.lang.Object"
    INVOKESTATIC java/lang/Class.forName (Ljava/lang/String;)Ljava/lang/Class;
    LDC "hashCode"
    ICONST_0
    ANEWARRAY java/lang/Class
    INVOKEVIRTUAL java/lang/Class.getMethod (Ljava/lang/String;[Ljava/lang/Class;)Ljava/lang/reflect/Method;
    PUTSTATIC org/devx/spring/certified/professional/edu/course/a12/$Proxy0.m0 : Ljava/lang/reflect/Method;
   L1
    LINENUMBER 76 L1
    GOTO L7
   L2
    LINENUMBER 77 L2
   FRAME SAME1 java/lang/NoSuchMethodException
    ASTORE 0
   L8
    LINENUMBER 78 L8
    NEW java/lang/NoSuchMethodError
    DUP
    ALOAD 0
    INVOKEVIRTUAL java/lang/NoSuchMethodException.getMessage ()Ljava/lang/String;
    INVOKESPECIAL java/lang/NoSuchMethodError.<init> (Ljava/lang/String;)V
    ATHROW
   L3
    LINENUMBER 80 L3
   FRAME SAME1 java/lang/ClassNotFoundException
    ASTORE 0
   L9
    LINENUMBER 81 L9
    NEW java/lang/NoClassDefFoundError
    DUP
    ALOAD 0
    INVOKEVIRTUAL java/lang/ClassNotFoundException.getMessage ()Ljava/lang/String;
    INVOKESPECIAL java/lang/NoClassDefFoundError.<init> (Ljava/lang/String;)V
    ATHROW
   L7
    LINENUMBER 83 L7
   FRAME SAME
    RETURN
    LOCALVARIABLE noSuchMethodException Ljava/lang/NoSuchMethodException; L8 L3 0
    LOCALVARIABLE classNotFoundException Ljava/lang/ClassNotFoundException; L9 L7 0
    MAXSTACK = 6
    MAXLOCALS = 1

  // access flags 0x1
  public <init>(Ljava/lang/reflect/InvocationHandler;)V
  ATTRIBUTE org.aspectj.weaver.MethodDeclarationLineNumber : unknown
   L0
    LINENUMBER 18 L0
    ALOAD 0
    ALOAD 1
    INVOKESPECIAL java/lang/reflect/Proxy.<init> (Ljava/lang/reflect/InvocationHandler;)V
   L1
    LINENUMBER 19 L1
    RETURN
   L2
    LOCALVARIABLE this Lorg/devx/spring/certified/professional/edu/course/a12/$Proxy0; L0 L2 0
    LOCALVARIABLE invocationHandler Ljava/lang/reflect/InvocationHandler; L0 L2 1
    MAXSTACK = 2
    MAXLOCALS = 2

  // access flags 0x11
  public final equals(Ljava/lang/Object;)Z
  ATTRIBUTE org.aspectj.weaver.MethodDeclarationLineNumber : unknown
    TRYCATCHBLOCK L0 L1 L2 java/lang/Error
    TRYCATCHBLOCK L0 L1 L2 java/lang/RuntimeException
    TRYCATCHBLOCK L0 L1 L3 java/lang/Throwable
   L0
    LINENUMBER 23 L0
    ALOAD 0
    GETFIELD org/devx/spring/certified/professional/edu/course/a12/$Proxy0.h : Ljava/lang/reflect/InvocationHandler;
    ALOAD 0
    GETSTATIC org/devx/spring/certified/professional/edu/course/a12/$Proxy0.m1 : Ljava/lang/reflect/Method;
    ICONST_1
    ANEWARRAY java/lang/Object
    DUP
    ICONST_0
    ALOAD 1
    AASTORE
    INVOKEINTERFACE java/lang/reflect/InvocationHandler.invoke (Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;
    CHECKCAST java/lang/Boolean
    INVOKEVIRTUAL java/lang/Boolean.booleanValue ()Z
   L1
    IRETURN
   L2
    LINENUMBER 25 L2
   FRAME SAME1 java/lang/Throwable
    ASTORE 2
   L4
    LINENUMBER 26 L4
    ALOAD 2
    ATHROW
   L3
    LINENUMBER 28 L3
   FRAME SAME1 java/lang/Throwable
    ASTORE 2
   L5
    LINENUMBER 29 L5
    NEW java/lang/reflect/UndeclaredThrowableException
    DUP
    ALOAD 2
    INVOKESPECIAL java/lang/reflect/UndeclaredThrowableException.<init> (Ljava/lang/Throwable;)V
    ATHROW
   L6
    LOCALVARIABLE this Lorg/devx/spring/certified/professional/edu/course/a12/$Proxy0; L0 L6 0
    LOCALVARIABLE object Ljava/lang/Object; L0 L6 1
    LOCALVARIABLE throwable Ljava/lang/Throwable; L4 L3 2
    LOCALVARIABLE throwable Ljava/lang/Throwable; L5 L6 2
    MAXSTACK = 7
    MAXLOCALS = 3

  // access flags 0x11
  public final toString()Ljava/lang/String;
  ATTRIBUTE org.aspectj.weaver.MethodDeclarationLineNumber : unknown
    TRYCATCHBLOCK L0 L1 L2 java/lang/Error
    TRYCATCHBLOCK L0 L1 L2 java/lang/RuntimeException
    TRYCATCHBLOCK L0 L1 L3 java/lang/Throwable
   L0
    LINENUMBER 35 L0
    ALOAD 0
    GETFIELD org/devx/spring/certified/professional/edu/course/a12/$Proxy0.h : Ljava/lang/reflect/InvocationHandler;
    ALOAD 0
    GETSTATIC org/devx/spring/certified/professional/edu/course/a12/$Proxy0.m2 : Ljava/lang/reflect/Method;
    ACONST_NULL
    INVOKEINTERFACE java/lang/reflect/InvocationHandler.invoke (Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;
    CHECKCAST java/lang/String
   L1
    ARETURN
   L2
    LINENUMBER 37 L2
   FRAME SAME1 java/lang/Throwable
    ASTORE 1
   L4
    LINENUMBER 38 L4
    ALOAD 1
    ATHROW
   L3
    LINENUMBER 40 L3
   FRAME SAME1 java/lang/Throwable
    ASTORE 1
   L5
    LINENUMBER 41 L5
    NEW java/lang/reflect/UndeclaredThrowableException
    DUP
    ALOAD 1
    INVOKESPECIAL java/lang/reflect/UndeclaredThrowableException.<init> (Ljava/lang/Throwable;)V
    ATHROW
   L6
    LOCALVARIABLE this Lorg/devx/spring/certified/professional/edu/course/a12/$Proxy0; L0 L6 0
    LOCALVARIABLE throwable Ljava/lang/Throwable; L4 L3 1
    LOCALVARIABLE throwable Ljava/lang/Throwable; L5 L6 1
    MAXSTACK = 4
    MAXLOCALS = 2

  // access flags 0x11
  public final foo()V
  ATTRIBUTE org.aspectj.weaver.MethodDeclarationLineNumber : unknown
    TRYCATCHBLOCK L0 L1 L2 java/lang/Error
    TRYCATCHBLOCK L0 L1 L2 java/lang/RuntimeException
    TRYCATCHBLOCK L0 L1 L3 java/lang/Throwable
   L0
    LINENUMBER 47 L0
    ALOAD 0
    GETFIELD org/devx/spring/certified/professional/edu/course/a12/$Proxy0.h : Ljava/lang/reflect/InvocationHandler;
    ALOAD 0
    GETSTATIC org/devx/spring/certified/professional/edu/course/a12/$Proxy0.m3 : Ljava/lang/reflect/Method;
    ACONST_NULL
    INVOKEINTERFACE java/lang/reflect/InvocationHandler.invoke (Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;
    POP
   L1
    LINENUMBER 48 L1
    RETURN
   L2
    LINENUMBER 50 L2
   FRAME SAME1 java/lang/Throwable
    ASTORE 1
   L4
    LINENUMBER 51 L4
    ALOAD 1
    ATHROW
   L3
    LINENUMBER 53 L3
   FRAME SAME1 java/lang/Throwable
    ASTORE 1
   L5
    LINENUMBER 54 L5
    NEW java/lang/reflect/UndeclaredThrowableException
    DUP
    ALOAD 1
    INVOKESPECIAL java/lang/reflect/UndeclaredThrowableException.<init> (Ljava/lang/Throwable;)V
    ATHROW
   L6
    LOCALVARIABLE this Lorg/devx/spring/certified/professional/edu/course/a12/$Proxy0; L0 L6 0
    LOCALVARIABLE throwable Ljava/lang/Throwable; L4 L3 1
    LOCALVARIABLE throwable Ljava/lang/Throwable; L5 L6 1
    MAXSTACK = 4
    MAXLOCALS = 2

  // access flags 0x11
  public final hashCode()I
  ATTRIBUTE org.aspectj.weaver.MethodDeclarationLineNumber : unknown
    TRYCATCHBLOCK L0 L1 L2 java/lang/Error
    TRYCATCHBLOCK L0 L1 L2 java/lang/RuntimeException
    TRYCATCHBLOCK L0 L1 L3 java/lang/Throwable
   L0
    LINENUMBER 60 L0
    ALOAD 0
    GETFIELD org/devx/spring/certified/professional/edu/course/a12/$Proxy0.h : Ljava/lang/reflect/InvocationHandler;
    ALOAD 0
    GETSTATIC org/devx/spring/certified/professional/edu/course/a12/$Proxy0.m0 : Ljava/lang/reflect/Method;
    ACONST_NULL
    INVOKEINTERFACE java/lang/reflect/InvocationHandler.invoke (Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;
    CHECKCAST java/lang/Integer
    INVOKEVIRTUAL java/lang/Integer.intValue ()I
   L1
    IRETURN
   L2
    LINENUMBER 62 L2
   FRAME SAME1 java/lang/Throwable
    ASTORE 1
   L4
    LINENUMBER 63 L4
    ALOAD 1
    ATHROW
   L3
    LINENUMBER 65 L3
   FRAME SAME1 java/lang/Throwable
    ASTORE 1
   L5
    LINENUMBER 66 L5
    NEW java/lang/reflect/UndeclaredThrowableException
    DUP
    ALOAD 1
    INVOKESPECIAL java/lang/reflect/UndeclaredThrowableException.<init> (Ljava/lang/Throwable;)V
    ATHROW
   L6
    LOCALVARIABLE this Lorg/devx/spring/certified/professional/edu/course/a12/$Proxy0; L0 L6 0
    LOCALVARIABLE throwable Ljava/lang/Throwable; L4 L3 1
    LOCALVARIABLE throwable Ljava/lang/Throwable; L5 L6 1
    MAXSTACK = 4
    MAXLOCALS = 2
}

生成代理对象字节码的代码

该代码由 ASM Bytecode Outline 插件提供.

package asm.org.devx.spring.certified.professional.edu.course.a12;

import java.util.*;

import org.objectweb.asm.*;

public class $Proxy0Dump implements Opcodes {

    public static byte[] dump() throws Exception {

        ClassWriter cw = new ClassWriter(0);
        FieldVisitor fv;
        MethodVisitor mv;
        AnnotationVisitor av0;

        cw.visit(52, ACC_FINAL + ACC_SUPER, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", null, "java/lang/reflect/Proxy", new String[]{"org/devx/spring/certified/professional/edu/course/a12/JdkProxyDemo$Foo"});

        cw.visitSource("$Proxy0.java", null);

        cw.visitInnerClass("org/devx/spring/certified/professional/edu/course/a12/JdkProxyDemo$Foo", "org/devx/spring/certified/professional/edu/course/a12/JdkProxyDemo", "Foo", ACC_STATIC + ACC_ABSTRACT + ACC_INTERFACE);

        {
            fv = cw.visitField(ACC_PRIVATE + ACC_STATIC, "m1", "Ljava/lang/reflect/Method;", null, null);
            fv.visitEnd();
        }
        {
            fv = cw.visitField(ACC_PRIVATE + ACC_STATIC, "m2", "Ljava/lang/reflect/Method;", null, null);
            fv.visitEnd();
        }
        {
            fv = cw.visitField(ACC_PRIVATE + ACC_STATIC, "m3", "Ljava/lang/reflect/Method;", null, null);
            fv.visitEnd();
        }
        {
            fv = cw.visitField(ACC_PRIVATE + ACC_STATIC, "m0", "Ljava/lang/reflect/Method;", null, null);
            fv.visitEnd();
        }
        {
            mv = cw.visitMethod(ACC_STATIC, "<clinit>", "()V", null, null);
            mv.visitCode();
            Label l0 = new Label();
            Label l1 = new Label();
            Label l2 = new Label();
            mv.visitTryCatchBlock(l0, l1, l2, "java/lang/NoSuchMethodException");
            Label l3 = new Label();
            mv.visitTryCatchBlock(l0, l1, l3, "java/lang/ClassNotFoundException");
            mv.visitLabel(l0);
            mv.visitLineNumber(72, l0);
            mv.visitLdcInsn("java.lang.Object");
            mv.visitMethodInsn(INVOKESTATIC, "java/lang/Class", "forName", "(Ljava/lang/String;)Ljava/lang/Class;", false);
            mv.visitLdcInsn("equals");
            mv.visitInsn(ICONST_1);
            mv.visitTypeInsn(ANEWARRAY, "java/lang/Class");
            mv.visitInsn(DUP);
            mv.visitInsn(ICONST_0);
            mv.visitLdcInsn("java.lang.Object");
            mv.visitMethodInsn(INVOKESTATIC, "java/lang/Class", "forName", "(Ljava/lang/String;)Ljava/lang/Class;", false);
            mv.visitInsn(AASTORE);
            mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Class", "getMethod", "(Ljava/lang/String;[Ljava/lang/Class;)Ljava/lang/reflect/Method;", false);
            mv.visitFieldInsn(PUTSTATIC, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", "m1", "Ljava/lang/reflect/Method;");
            Label l4 = new Label();
            mv.visitLabel(l4);
            mv.visitLineNumber(73, l4);
            mv.visitLdcInsn("java.lang.Object");
            mv.visitMethodInsn(INVOKESTATIC, "java/lang/Class", "forName", "(Ljava/lang/String;)Ljava/lang/Class;", false);
            mv.visitLdcInsn("toString");
            mv.visitInsn(ICONST_0);
            mv.visitTypeInsn(ANEWARRAY, "java/lang/Class");
            mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Class", "getMethod", "(Ljava/lang/String;[Ljava/lang/Class;)Ljava/lang/reflect/Method;", false);
            mv.visitFieldInsn(PUTSTATIC, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", "m2", "Ljava/lang/reflect/Method;");
            Label l5 = new Label();
            mv.visitLabel(l5);
            mv.visitLineNumber(74, l5);
            mv.visitLdcInsn("org.devx.spring.certified.professional.edu.course.a12.JdkProxyDemo$Foo");
            mv.visitMethodInsn(INVOKESTATIC, "java/lang/Class", "forName", "(Ljava/lang/String;)Ljava/lang/Class;", false);
            mv.visitLdcInsn("foo");
            mv.visitInsn(ICONST_0);
            mv.visitTypeInsn(ANEWARRAY, "java/lang/Class");
            mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Class", "getMethod", "(Ljava/lang/String;[Ljava/lang/Class;)Ljava/lang/reflect/Method;", false);
            mv.visitFieldInsn(PUTSTATIC, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", "m3", "Ljava/lang/reflect/Method;");
            Label l6 = new Label();
            mv.visitLabel(l6);
            mv.visitLineNumber(75, l6);
            mv.visitLdcInsn("java.lang.Object");
            mv.visitMethodInsn(INVOKESTATIC, "java/lang/Class", "forName", "(Ljava/lang/String;)Ljava/lang/Class;", false);
            mv.visitLdcInsn("hashCode");
            mv.visitInsn(ICONST_0);
            mv.visitTypeInsn(ANEWARRAY, "java/lang/Class");
            mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Class", "getMethod", "(Ljava/lang/String;[Ljava/lang/Class;)Ljava/lang/reflect/Method;", false);
            mv.visitFieldInsn(PUTSTATIC, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", "m0", "Ljava/lang/reflect/Method;");
            mv.visitLabel(l1);
            mv.visitLineNumber(76, l1);
            Label l7 = new Label();
            mv.visitJumpInsn(GOTO, l7);
            mv.visitLabel(l2);
            mv.visitLineNumber(77, l2);
            mv.visitFrame(Opcodes.F_SAME1, 0, null, 1, new Object[]{"java/lang/NoSuchMethodException"});
            mv.visitVarInsn(ASTORE, 0);
            Label l8 = new Label();
            mv.visitLabel(l8);
            mv.visitLineNumber(78, l8);
            mv.visitTypeInsn(NEW, "java/lang/NoSuchMethodError");
            mv.visitInsn(DUP);
            mv.visitVarInsn(ALOAD, 0);
            mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/NoSuchMethodException", "getMessage", "()Ljava/lang/String;", false);
            mv.visitMethodInsn(INVOKESPECIAL, "java/lang/NoSuchMethodError", "<init>", "(Ljava/lang/String;)V", false);
            mv.visitInsn(ATHROW);
            mv.visitLabel(l3);
            mv.visitLineNumber(80, l3);
            mv.visitFrame(Opcodes.F_SAME1, 0, null, 1, new Object[]{"java/lang/ClassNotFoundException"});
            mv.visitVarInsn(ASTORE, 0);
            Label l9 = new Label();
            mv.visitLabel(l9);
            mv.visitLineNumber(81, l9);
            mv.visitTypeInsn(NEW, "java/lang/NoClassDefFoundError");
            mv.visitInsn(DUP);
            mv.visitVarInsn(ALOAD, 0);
            mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/ClassNotFoundException", "getMessage", "()Ljava/lang/String;", false);
            mv.visitMethodInsn(INVOKESPECIAL, "java/lang/NoClassDefFoundError", "<init>", "(Ljava/lang/String;)V", false);
            mv.visitInsn(ATHROW);
            mv.visitLabel(l7);
            mv.visitLineNumber(83, l7);
            mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
            mv.visitInsn(RETURN);
            mv.visitLocalVariable("noSuchMethodException", "Ljava/lang/NoSuchMethodException;", null, l8, l3, 0);
            mv.visitLocalVariable("classNotFoundException", "Ljava/lang/ClassNotFoundException;", null, l9, l7, 0);
            mv.visitMaxs(6, 1);
            mv.visitEnd();
        }
        {
            mv = cw.visitMethod(ACC_PUBLIC, "<init>", "(Ljava/lang/reflect/InvocationHandler;)V", null, null);
// ATTRIBUTE org.aspectj.weaver.MethodDeclarationLineNumber
            mv.visitCode();
            Label l0 = new Label();
            mv.visitLabel(l0);
            mv.visitLineNumber(18, l0);
            mv.visitVarInsn(ALOAD, 0);
            mv.visitVarInsn(ALOAD, 1);
            mv.visitMethodInsn(INVOKESPECIAL, "java/lang/reflect/Proxy", "<init>", "(Ljava/lang/reflect/InvocationHandler;)V", false);
            Label l1 = new Label();
            mv.visitLabel(l1);
            mv.visitLineNumber(19, l1);
            mv.visitInsn(RETURN);
            Label l2 = new Label();
            mv.visitLabel(l2);
            mv.visitLocalVariable("this", "Lorg/devx/spring/certified/professional/edu/course/a12/$Proxy0;", null, l0, l2, 0);
            mv.visitLocalVariable("invocationHandler", "Ljava/lang/reflect/InvocationHandler;", null, l0, l2, 1);
            mv.visitMaxs(2, 2);
            mv.visitEnd();
        }
        {
            mv = cw.visitMethod(ACC_PUBLIC + ACC_FINAL, "equals", "(Ljava/lang/Object;)Z", null, null);
// ATTRIBUTE org.aspectj.weaver.MethodDeclarationLineNumber
            mv.visitCode();
            Label l0 = new Label();
            Label l1 = new Label();
            Label l2 = new Label();
            mv.visitTryCatchBlock(l0, l1, l2, "java/lang/Error");
            mv.visitTryCatchBlock(l0, l1, l2, "java/lang/RuntimeException");
            Label l3 = new Label();
            mv.visitTryCatchBlock(l0, l1, l3, "java/lang/Throwable");
            mv.visitLabel(l0);
            mv.visitLineNumber(23, l0);
            mv.visitVarInsn(ALOAD, 0);
            mv.visitFieldInsn(GETFIELD, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", "h", "Ljava/lang/reflect/InvocationHandler;");
            mv.visitVarInsn(ALOAD, 0);
            mv.visitFieldInsn(GETSTATIC, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", "m1", "Ljava/lang/reflect/Method;");
            mv.visitInsn(ICONST_1);
            mv.visitTypeInsn(ANEWARRAY, "java/lang/Object");
            mv.visitInsn(DUP);
            mv.visitInsn(ICONST_0);
            mv.visitVarInsn(ALOAD, 1);
            mv.visitInsn(AASTORE);
            mv.visitMethodInsn(INVOKEINTERFACE, "java/lang/reflect/InvocationHandler", "invoke", "(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;", true);
            mv.visitTypeInsn(CHECKCAST, "java/lang/Boolean");
            mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Boolean", "booleanValue", "()Z", false);
            mv.visitLabel(l1);
            mv.visitInsn(IRETURN);
            mv.visitLabel(l2);
            mv.visitLineNumber(25, l2);
            mv.visitFrame(Opcodes.F_SAME1, 0, null, 1, new Object[]{"java/lang/Throwable"});
            mv.visitVarInsn(ASTORE, 2);
            Label l4 = new Label();
            mv.visitLabel(l4);
            mv.visitLineNumber(26, l4);
            mv.visitVarInsn(ALOAD, 2);
            mv.visitInsn(ATHROW);
            mv.visitLabel(l3);
            mv.visitLineNumber(28, l3);
            mv.visitFrame(Opcodes.F_SAME1, 0, null, 1, new Object[]{"java/lang/Throwable"});
            mv.visitVarInsn(ASTORE, 2);
            Label l5 = new Label();
            mv.visitLabel(l5);
            mv.visitLineNumber(29, l5);
            mv.visitTypeInsn(NEW, "java/lang/reflect/UndeclaredThrowableException");
            mv.visitInsn(DUP);
            mv.visitVarInsn(ALOAD, 2);
            mv.visitMethodInsn(INVOKESPECIAL, "java/lang/reflect/UndeclaredThrowableException", "<init>", "(Ljava/lang/Throwable;)V", false);
            mv.visitInsn(ATHROW);
            Label l6 = new Label();
            mv.visitLabel(l6);
            mv.visitLocalVariable("this", "Lorg/devx/spring/certified/professional/edu/course/a12/$Proxy0;", null, l0, l6, 0);
            mv.visitLocalVariable("object", "Ljava/lang/Object;", null, l0, l6, 1);
            mv.visitLocalVariable("throwable", "Ljava/lang/Throwable;", null, l4, l3, 2);
            mv.visitLocalVariable("throwable", "Ljava/lang/Throwable;", null, l5, l6, 2);
            mv.visitMaxs(7, 3);
            mv.visitEnd();
        }
        {
            mv = cw.visitMethod(ACC_PUBLIC + ACC_FINAL, "toString", "()Ljava/lang/String;", null, null);
// ATTRIBUTE org.aspectj.weaver.MethodDeclarationLineNumber
            mv.visitCode();
            Label l0 = new Label();
            Label l1 = new Label();
            Label l2 = new Label();
            mv.visitTryCatchBlock(l0, l1, l2, "java/lang/Error");
            mv.visitTryCatchBlock(l0, l1, l2, "java/lang/RuntimeException");
            Label l3 = new Label();
            mv.visitTryCatchBlock(l0, l1, l3, "java/lang/Throwable");
            mv.visitLabel(l0);
            mv.visitLineNumber(35, l0);
            mv.visitVarInsn(ALOAD, 0);
            mv.visitFieldInsn(GETFIELD, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", "h", "Ljava/lang/reflect/InvocationHandler;");
            mv.visitVarInsn(ALOAD, 0);
            mv.visitFieldInsn(GETSTATIC, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", "m2", "Ljava/lang/reflect/Method;");
            mv.visitInsn(ACONST_NULL);
            mv.visitMethodInsn(INVOKEINTERFACE, "java/lang/reflect/InvocationHandler", "invoke", "(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;", true);
            mv.visitTypeInsn(CHECKCAST, "java/lang/String");
            mv.visitLabel(l1);
            mv.visitInsn(ARETURN);
            mv.visitLabel(l2);
            mv.visitLineNumber(37, l2);
            mv.visitFrame(Opcodes.F_SAME1, 0, null, 1, new Object[]{"java/lang/Throwable"});
            mv.visitVarInsn(ASTORE, 1);
            Label l4 = new Label();
            mv.visitLabel(l4);
            mv.visitLineNumber(38, l4);
            mv.visitVarInsn(ALOAD, 1);
            mv.visitInsn(ATHROW);
            mv.visitLabel(l3);
            mv.visitLineNumber(40, l3);
            mv.visitFrame(Opcodes.F_SAME1, 0, null, 1, new Object[]{"java/lang/Throwable"});
            mv.visitVarInsn(ASTORE, 1);
            Label l5 = new Label();
            mv.visitLabel(l5);
            mv.visitLineNumber(41, l5);
            mv.visitTypeInsn(NEW, "java/lang/reflect/UndeclaredThrowableException");
            mv.visitInsn(DUP);
            mv.visitVarInsn(ALOAD, 1);
            mv.visitMethodInsn(INVOKESPECIAL, "java/lang/reflect/UndeclaredThrowableException", "<init>", "(Ljava/lang/Throwable;)V", false);
            mv.visitInsn(ATHROW);
            Label l6 = new Label();
            mv.visitLabel(l6);
            mv.visitLocalVariable("this", "Lorg/devx/spring/certified/professional/edu/course/a12/$Proxy0;", null, l0, l6, 0);
            mv.visitLocalVariable("throwable", "Ljava/lang/Throwable;", null, l4, l3, 1);
            mv.visitLocalVariable("throwable", "Ljava/lang/Throwable;", null, l5, l6, 1);
            mv.visitMaxs(4, 2);
            mv.visitEnd();
        }
        {
            mv = cw.visitMethod(ACC_PUBLIC + ACC_FINAL, "foo", "()V", null, null);
// ATTRIBUTE org.aspectj.weaver.MethodDeclarationLineNumber
            mv.visitCode();
            Label l0 = new Label();
            Label l1 = new Label();
            Label l2 = new Label();
            mv.visitTryCatchBlock(l0, l1, l2, "java/lang/Error");
            mv.visitTryCatchBlock(l0, l1, l2, "java/lang/RuntimeException");
            Label l3 = new Label();
            mv.visitTryCatchBlock(l0, l1, l3, "java/lang/Throwable");
            mv.visitLabel(l0);
            mv.visitLineNumber(47, l0);
            mv.visitVarInsn(ALOAD, 0);
            mv.visitFieldInsn(GETFIELD, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", "h", "Ljava/lang/reflect/InvocationHandler;");
            mv.visitVarInsn(ALOAD, 0);
            mv.visitFieldInsn(GETSTATIC, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", "m3", "Ljava/lang/reflect/Method;");
            mv.visitInsn(ACONST_NULL);
            mv.visitMethodInsn(INVOKEINTERFACE, "java/lang/reflect/InvocationHandler", "invoke", "(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;", true);
            mv.visitInsn(POP);
            mv.visitLabel(l1);
            mv.visitLineNumber(48, l1);
            mv.visitInsn(RETURN);
            mv.visitLabel(l2);
            mv.visitLineNumber(50, l2);
            mv.visitFrame(Opcodes.F_SAME1, 0, null, 1, new Object[]{"java/lang/Throwable"});
            mv.visitVarInsn(ASTORE, 1);
            Label l4 = new Label();
            mv.visitLabel(l4);
            mv.visitLineNumber(51, l4);
            mv.visitVarInsn(ALOAD, 1);
            mv.visitInsn(ATHROW);
            mv.visitLabel(l3);
            mv.visitLineNumber(53, l3);
            mv.visitFrame(Opcodes.F_SAME1, 0, null, 1, new Object[]{"java/lang/Throwable"});
            mv.visitVarInsn(ASTORE, 1);
            Label l5 = new Label();
            mv.visitLabel(l5);
            mv.visitLineNumber(54, l5);
            mv.visitTypeInsn(NEW, "java/lang/reflect/UndeclaredThrowableException");
            mv.visitInsn(DUP);
            mv.visitVarInsn(ALOAD, 1);
            mv.visitMethodInsn(INVOKESPECIAL, "java/lang/reflect/UndeclaredThrowableException", "<init>", "(Ljava/lang/Throwable;)V", false);
            mv.visitInsn(ATHROW);
            Label l6 = new Label();
            mv.visitLabel(l6);
            mv.visitLocalVariable("this", "Lorg/devx/spring/certified/professional/edu/course/a12/$Proxy0;", null, l0, l6, 0);
            mv.visitLocalVariable("throwable", "Ljava/lang/Throwable;", null, l4, l3, 1);
            mv.visitLocalVariable("throwable", "Ljava/lang/Throwable;", null, l5, l6, 1);
            mv.visitMaxs(4, 2);
            mv.visitEnd();
        }
        {
            mv = cw.visitMethod(ACC_PUBLIC + ACC_FINAL, "hashCode", "()I", null, null);
// ATTRIBUTE org.aspectj.weaver.MethodDeclarationLineNumber
            mv.visitCode();
            Label l0 = new Label();
            Label l1 = new Label();
            Label l2 = new Label();
            mv.visitTryCatchBlock(l0, l1, l2, "java/lang/Error");
            mv.visitTryCatchBlock(l0, l1, l2, "java/lang/RuntimeException");
            Label l3 = new Label();
            mv.visitTryCatchBlock(l0, l1, l3, "java/lang/Throwable");
            mv.visitLabel(l0);
            mv.visitLineNumber(60, l0);
            mv.visitVarInsn(ALOAD, 0);
            mv.visitFieldInsn(GETFIELD, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", "h", "Ljava/lang/reflect/InvocationHandler;");
            mv.visitVarInsn(ALOAD, 0);
            mv.visitFieldInsn(GETSTATIC, "org/devx/spring/certified/professional/edu/course/a12/$Proxy0", "m0", "Ljava/lang/reflect/Method;");
            mv.visitInsn(ACONST_NULL);
            mv.visitMethodInsn(INVOKEINTERFACE, "java/lang/reflect/InvocationHandler", "invoke", "(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;", true);
            mv.visitTypeInsn(CHECKCAST, "java/lang/Integer");
            mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Integer", "intValue", "()I", false);
            mv.visitLabel(l1);
            mv.visitInsn(IRETURN);
            mv.visitLabel(l2);
            mv.visitLineNumber(62, l2);
            mv.visitFrame(Opcodes.F_SAME1, 0, null, 1, new Object[]{"java/lang/Throwable"});
            mv.visitVarInsn(ASTORE, 1);
            Label l4 = new Label();
            mv.visitLabel(l4);
            mv.visitLineNumber(63, l4);
            mv.visitVarInsn(ALOAD, 1);
            mv.visitInsn(ATHROW);
            mv.visitLabel(l3);
            mv.visitLineNumber(65, l3);
            mv.visitFrame(Opcodes.F_SAME1, 0, null, 1, new Object[]{"java/lang/Throwable"});
            mv.visitVarInsn(ASTORE, 1);
            Label l5 = new Label();
            mv.visitLabel(l5);
            mv.visitLineNumber(66, l5);
            mv.visitTypeInsn(NEW, "java/lang/reflect/UndeclaredThrowableException");
            mv.visitInsn(DUP);
            mv.visitVarInsn(ALOAD, 1);
            mv.visitMethodInsn(INVOKESPECIAL, "java/lang/reflect/UndeclaredThrowableException", "<init>", "(Ljava/lang/Throwable;)V", false);
            mv.visitInsn(ATHROW);
            Label l6 = new Label();
            mv.visitLabel(l6);
            mv.visitLocalVariable("this", "Lorg/devx/spring/certified/professional/edu/course/a12/$Proxy0;", null, l0, l6, 0);
            mv.visitLocalVariable("throwable", "Ljava/lang/Throwable;", null, l4, l3, 1);
            mv.visitLocalVariable("throwable", "Ljava/lang/Throwable;", null, l5, l6, 1);
            mv.visitMaxs(4, 2);
            mv.visitEnd();
        }
        cw.visitEnd();

        return cw.toByteArray();
    }
}

验证

使用上面生成代理对象字节码的java代码进行验证，测试生成的代理对象能否正常工作.

public class TestProxy0Dump {

    public static void main(String[] args) throws Exception {

        byte[] bytes = $Proxy0Dump.dump();

        ClassLoader classLoader = new ClassLoader() {
            @Override
            protected Class<?> findClass(String name) throws ClassNotFoundException {
                return super.defineClass(name, bytes, 0, bytes.length);
            }
        };

        JdkProxyDemo.Target target = new JdkProxyDemo.Target();

        Class<?> proxyClass = classLoader.loadClass("org.devx.spring.certified.professional.edu.course.a12.$Proxy0");
        Constructor<?> constructor = proxyClass.getConstructor(InvocationHandler.class);
        JdkProxyDemo.Foo proxy = (JdkProxyDemo.Foo) constructor.newInstance(new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                System.out.println("before --------------------------------");
                Object ret = method.invoke(target, args);
                System.out.println("after --------------------------------");
                return ret;
            }
        });

        proxy.foo();
    }

更多技术干货会在后续内容中提供。该文章会同步在微信公众号 【DevXJava】, 方便在微信客户端阅读。

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原文作者：DevXTalk；如有侵权，请联系管理员删除。

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