CGLIB's steps and instance analysis of creating dynamic proxy class
CGLIB's steps and instance analysis of creating dynamic proxy class
Overview:
CGLIB is a powerful Java bytecode generating library, which is widely used to create dynamic proxy classes.Compared with the standard dynamic agency mechanism of Java, CGLIB does not need to implement the interface and can directly represent ordinary classes.This article will introduce the steps to create a dynamic proxy class with CGLIB and provide Java code examples to analyze this process.
step:
The following is the main step of using CGLIB to create a dynamic proxy class:
1. Import related dependencies:
First, import the relevant dependencies of CGLIB in your Java project.You can add the following dependencies through building tools such as Maven or Gradle:
dependencies {
// CGLib Core
implementation 'org.springframework.boot:spring-boot-starter-aop'
implementation 'org.springframework.boot:spring-boot-starter-web'
implementation 'cglib:cglib:3.3.0'
}
2. Create the target class:
Then, create a target class, which is the class you want to act.This class can be an ordinary Java class without any interface.
public class TargetClass {
public void performAction() {
System.out.println("Performing the action...");
}
}
3. Create proxy category:
Next, create a proxy class with CGLIB.You can use the Create () method of the Enhancer class to implement this step.
public class ProxyClass implements MethodInterceptor {
public Object createProxy(Object target) {
Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(target.getClass());
enhancer.setCallback(this);
return enhancer.create();
}
@Override
public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
System.out.println("Before executing the method...");
Object result = proxy.invokeSuper(obj, args);
System.out.println("After executing the method...");
return result;
}
}
4. Use the proxy class:
Finally, use the generated proxy classes instead of the target class.
public class Main {
public static void main(String[] args) {
TargetClass target = new TargetClass();
ProxyClass proxy = new ProxyClass();
TargetClass proxyTarget = (TargetClass) proxy.createProxy(target);
// Through the proxy class call the target class method
proxyTarget.performAction();
}
}
Example analysis:
In this example, we created a target class called TargetClass with a Performaction () method.Then, we used CGLIB to create a proxy class called ProxyClass and implemented the MethodinterCePTOR interface.In the intercept () method, we can perform some operations before and after the method execute.Finally, in the main () method, we create instances of targetClass, and use proxyClass to generate proxy Proxy and pass the target object to it.Under the proxy Proxy calling the Performaction () method, in fact, the operation of the intercept () method will be performed, that is, printing some information before and after the method execution.
Summarize:
This article introduces the steps to create a dynamic proxy class with CGLIB and analyze this process through the sample code.CGLib provides a powerful way to create a dynamic proxy class, without the need for the target class to implement the interface.It can be used in actual development to achieve various application scenarios such as AOP (facing surface programming).
