Interpret the technical principles and applications of the CGLIB Nodep framework in the Java class library
The CGLIB Nodep framework is a widely used technology in the Java class library. This article will interpret its technical principles and applications and give it an example.
CGLIB (Code Generation Library) is a dynamic proxy framework generated by bytecode -based. It can be used without any third party dependencies in the Java class library.Compared to JAVA's JDK dynamic proxy, CGLIB can perform proxy by operating bytecode without implementing the interface. Therefore, it is widely used in various scenarios, such as AOP (facing cut programming), unit testing, initialization of certain operations, and certain operationswait.
The CGLIB Nodep framework is a variant of CGLIB, which solves the problem of CGLIB that may have conflicts in some environments.The CGLIB Nodep framework removed the dependencies of ASM (a Java bytecode operation framework) on the basis of CGLIB, making it easier to integrate and use.
The core technical principle of the CGLib Nodep framework is to achieve agents by generating subclasses that generate target class.When the method of calling the target class, CGLIB uses ASM library to operate the byte code and modify it to the corresponding method of calling the proxy class, thereby achieving intercepting the target class method.In this way, CGLIB can dynamically generate proxy classes during runtime, thereby replacing the original class function.
Below is a simple example that demonstrates the use of the CGLIB NODEP framework:
public class UserService {
public void saveUser(String username) {
System.out.println("Saving user: " + username);
}
}
public class UserServiceInterceptor implements MethodInterceptor {
@Override
public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
System.out.println("Before method: " + method.getName());
Object result = proxy.invokeSuper(obj, args);
System.out.println("After method: " + method.getName());
return result;
}
}
public class Main {
public static void main(String[] args) {
Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(UserService.class);
enhancer.setCallback(new UserServiceInterceptor());
UserService userService = (UserService) enhancer.create();
userService.saveUser("John");
}
}
In the above examples, we first define a `UserService` class, which contains a` SaveUser` method.Next, we define a `UserServiceInterceptor` class that implements CGLIB's` MethodInterceptor` interface, and intercept the target method in the `Internet` method to achieve the front and rear cut logic.
In the `Main` class, we created a proxy class with the` Enhancer` class.First of all, we specify the target class to be `userService`, and then set the proxy class callback object to the` userServiceInterceptor`.Finally, by calling the `enhancer.create () method, an instance of the proxy class is created.
When we call the agent class' Saveuser` method, CGLIB will automatically trigger the interception logic in the userServiceInterceptor`, first execute the front logic, then call the target method, and finally execute the rear logic.
Through the CGLIB Nodep framework, we can easily achieve dynamic proxy, intercept and expand the method of target class, so as to achieve various functional requirements, such as log records and transaction management.At the same time, CGLIB Nodep's non -dependence makes it a very convenient tool in Java development.
