字节码编程bytebuddy之获取方法信息和方法入参信息

写在前面

本文看下通过bytebuddy如何获取方法信息和方法的入参信息。

1：代码

package com.dahuyou.bytebuddy.bb;import com.dahuyou.bytebuddy.TT;
import net.bytebuddy.ByteBuddy;
import net.bytebuddy.dynamic.DynamicType;
import net.bytebuddy.implementation.MethodDelegation;
import net.bytebuddy.implementation.bind.annotation.*;
import net.bytebuddy.matcher.ElementMatchers;import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.concurrent.Callable;public class TTT {public static void main(String[] args) throws Exception {DynamicType.Unloaded<BizMethod> dynamicType = new ByteBuddy().subclass(BizMethod.class).method(ElementMatchers.named("queryUserInfo")).intercept(MethodDelegation.to(PrintMethodInfo.class)).make();DynamicType.Loaded<com.dahuyou.bytebuddy.bb.BizMethod> load = dynamicType.load(com.dahuyou.bytebuddy.aa.TTT.class.getClassLoader());// 执行插桩后的代码Class<? extends com.dahuyou.bytebuddy.bb.BizMethod> calzzz = load.getLoaded();calzzz.getMethod("queryUserInfo", String.class, String.class).invoke(calzzz.newInstance(), "89899", "黑咯Heloise");outputClazz(load.getBytes());}private static void outputClazz(byte[] bytes) {// 输出类字节码FileOutputStream out = null;try {String pathName = TT.class.getResource("/").getPath() + "AsmTestPrintMethodParam.class";out = new FileOutputStream(new File(pathName));System.out.println("ASM类输出路径：" + pathName);out.write(bytes);} catch (Exception e) {e.printStackTrace();} finally {if (null != out) try {out.close();} catch (IOException e) {e.printStackTrace();}}}public static class PrintMethodInfo {// 通过该注解标记为要执行的方法@RuntimeTypepublic static Object realRun(@SuperCall Callable<?> callable,@Origin Method method,@AllArguments Object[] args,@Argument(0) Object firstParam) throws Exception {long start = System.currentTimeMillis();Object resObj = null;try {resObj = callable.call();return resObj;} finally {System.out.println("方法名称：" + method.getName());System.out.println("入参值：" + Arrays.asList(args));System.out.println("第一个入参值：" + firstParam);System.out.println("入参个数：" + method.getParameterCount());System.out.println("入参类型：" + method.getParameterTypes()[0].getTypeName() + "、" + method.getParameterTypes()[1].getTypeName());System.out.println("出参类型：" + method.getReturnType().getName());System.out.println("出参结果：" + resObj);System.out.println("方法耗时：" + (System.currentTimeMillis() - start) + "ms");}}}
}

其中通过注解@Origin获取原始的方法对象，通过注解@AllArguments获取所有的入参，也可以通过@Argument(索引位置)来获取指定位置的参数，运行如下:

BizMethod.queryUserInfo
方法名称：queryUserInfo
入参值：[89899, 黑咯Heloise]
第一个入参值：89899
入参个数：2
入参类型：java.lang.String、java.lang.String
出参类型：java.lang.String
出参结果：bytebuddy 搞一搞吧！！！
方法耗时：25msProcess finished with exit code 0

生成的字节码如下：

package com.dahuyou.bytebuddy.bb;import com.dahuyou.bytebuddy.bb.BizMethod.ByteBuddy.XE2b1UHs.auxiliary.45oW83hf;
import com.dahuyou.bytebuddy.bb.TTT.PrintMethodInfo;public class BizMethod$ByteBuddy$XE2b1UHs extends BizMethod {public String queryUserInfo(String var1, String var2) throws InterruptedException {return (String)PrintMethodInfo.realRun(new 45oW83hf(this, var1, var2), cachedValue$ZzEPIYTs$gvqiiu0, new Object[]{var1, var2}, var1);}public BizMethod$ByteBuddy$XE2b1UHs() {}
}

可以看到bytebuddy是通过生成待增强类的子类来完成插桩的，也可以说是使用了代理、包装的思想，然后通过注解预留了很多的口让我们获取一些可能需要用到的信息。精妙的设计，完美屏蔽了复杂度，还保留了扩展性。