Comparison of the practice of BYTE BUDDY AGENT framework and Java Agent
The practice comparison of BYTE Buddy Agent framework with Java Agent
Overview:
In the development of Java applications, through dynamically modifying and enhancing bytecodes, some interesting and powerful functions can be achieved.BYTE Buddy Agent framework and Java Agent are two commonly used methods for dynamic bytecode modification in Java applications.This article will compare them and provide some examples of Java code in practice.
BYTE BUDDY AGENT framework:
Byte Buddy Agent is a powerful and easy -to -use bytecode generating and converting library.It provides a set of simple APIs that can generate, modify and load the Java bytecode during runtime by redefining categories.Using byte Buddy Agent can achieve various functions, such as creating subclasses, adding methods, modifying fields, and implementing interfaces.Below is an example of creating a dynamic proxy object using BYTE BUDDDY AGENT:
import net.bytebuddy.ByteBuddy;
import net.bytebuddy.implementation.MethodDelegation;
import net.bytebuddy.implementation.bind.annotation.AllArguments;
import net.bytebuddy.implementation.bind.annotation.Origin;
import net.bytebuddy.implementation.bind.annotation.RuntimeType;
import net.bytebuddy.implementation.bind.annotation.SuperCall;
import java.lang.reflect.Method;
import java.util.concurrent.Callable;
public class HelloWorldInterceptor {
@RuntimeType
public static Object intercept(@AllArguments Object[] allArguments,
@Origin Method method,
@SuperCall Callable<?> callable) throws Exception {
System.out.println("Hello World!");
return callable.call();
}
public static void main(String[] args) throws Exception {
HelloWorldInterceptor interceptor = new HelloWorldInterceptor();
HelloWorld hw = new ByteBuddy()
.subclass(HelloWorld.class)
.method(isDeclaredBy(HelloWorld.class))
.intercept(MethodDelegation.to(interceptor))
.make()
.load(HelloWorld.class.getClassLoader())
.getLoaded()
.newInstance();
hw.sayHello();
}
}
In the above examples, we use the Byte Buddy library to create a class called `HelloWorldInterceptor`, which contains a method called` Internet`, which will be called when the `Sayhello` method of the` HelloWorld` method of the `HelloWorld` is called.By running the above code, we can see "Hello World!" In the output.
Java Agent：
Java Agent is a mechanism provided by the Java virtual machine. It allows us to load and modify the byte code when the Java application starts.Using Java Agent, we can realize the function of modifying the byte code during the application of the application without re -compilation and deployment of the application.The following is a simple example of using Java Agent:
import java.lang.instrument.Instrumentation;
public class HelloWorldAgent {
public static void premain(String agentArgs, Instrumentation instrumentation) {
instrumentation.addTransformer((loader, className, classBeingRedefined, protectionDomain, classfileBuffer) -> {
System.out.println("Hello World!");
return classfileBuffer;
});
}
public static void main(String[] args) {
System.out.println("Hello World!");
}
}
In the above example, we define a class called `HelloWorldAgent`, which contains a method called` Premain`.This method is the entrance point of the Java Agent. It receives two parameters, one is the proxy parameter, and the other is the `Instrumentation" object.We use the `adDTRANSFORMER" method of the `Instrumentation` object in the` Premain` method to register a custom `ClassFiletransFormer` to convert the byte code when loading.The conversion method is to output "Hello World!" When loading class.
Compare:
BYTE Buddy Agent framework and Java Agent can be modified by bytecode during the running of the Java application, but they have some differences and characteristics.
-It simplicity and easy -to -use: byte Buddy Agent provides a simple and powerful API, making it easy to generate and convey the byte code.In contrast, Java Agent needs to implement the `ClassFiletransFormer` interface, and write complex code to process the bytecode modification.
-The functional richness: Byte Buddy Agent provides many advanced functions, such as dynamic proxy, interception method calls, modified structures, etc.This allows developers to achieve some complex functions easier.The function of Java Agent is relatively limited, and it is difficult to achieve complex bytecode modification operations.
-The applicability: byte Buddy Agent is more suitable for use inside the application, such as AOP (facing cut -on programming).And Java Agent is more suitable for the application to modify the byte code when the application starts to achieve some global enhancement and debugging functions.
-The performance: Since BYTE Buddy Agent generates bytecode in memory, it has higher execution efficiency compared to Java Agent.
in conclusion:
BYTE Buddy Agent framework and Java Agent are powerful tools for dynamic bytecode modification in Java applications.According to specific needs and scenes, developers can choose the right method.For simple application scenarios, Java Agent may be a more applicable choice.For more complicated application scenarios, especially when performing some advanced features within the application, Byte Buddy Agent provides more flexible and powerful tools.
