Use the "Mirror" framework in the Java Library to implement annotated programming
Use the "Mirror" framework in the Java Library to implement annotated programming
introduction:
With the development of the Java language, annotation -based programming has become more and more popular.With the help of annotations, we can provide additional metadata information in the program in the program to facilitate the implementation of specific operations.In the Java library, the "Mirror" framework is a powerful tool that enables us to achieve more flexible programming methods through annotations.Below, we will introduce how to use the Mirror framework to achieve annotation -based programming.
What is Mirror framework:
Mirror is a framework based on the Java metad programming (Metaprogramming), which can analyze and modify the Java class structure during runtime.It provides a set of annotations and tools that enable developers to achieve custom metadata processing through the annotations and runtime.Using the Mirror framework, we can dynamically modify, generate, and check the code during the compilation period to achieve more flexible and scalable programming.
How to use Mirror framework:
The following example will show how to use the Mirror framework to achieve annotation -based programming.
Step 1: Introduce Mirror framework
First of all, we need to add a Mirror framework dependency item in the project construction file (Pom.xml or Build.gradle).For example, if you use Maven, you can add the following content to the pom.xml file:
<dependency>
<groupId>net.vidageek</groupId>
<artifactId>mirror</artifactId>
<version>1.6.1</version>
</dependency>
Step 2: Define and use annotations
Next, we can define our own annotations and use it for categories or methods that need to be customized.For example, we can define a comment called "Loggable":
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD})
public @interface Loggable {
String value() default "";
}
In the above code, we used the `@RETENTION (RetentionPolicy.runtime)` annotation, indicating that we want to retain the information about the annotation during the runtime.
Step 3: Use Mirror framework to process annotations
Next, we can use the Mirror framework to handle these annotations.The following is a simple example that demonstrates how to use the Mirror framework to obtain the value of the annotation:
import net.vidageek.mirror.dsl.Mirror;
@Loggable("MyClass")
public class MyClass {
@Loggable("myMethod")
public void myMethod() {
System.out.println("Hello, World!");
}
public static void main(String[] args) {
MyClass myClass = new MyClass();
Mirror mirror = new Mirror();
String className = mirror.on(myClass.getClass())
.reflect()
.annotation(Loggable.class)
.atClass()
.getValue("value");
System.out.println("Class name: " + className);
String methodName = mirror.on(myClass.getClass())
.reflect()
.annotation(Loggable.class)
.atMethod("myMethod")
.getValue("value");
System.out.println("Method name: " + methodName);
}
}
In the above code, we first instantiated the Mirror class, and passed into the required class by calling the `On ()" method.Then, we use the `Reflect ()` method to obtain the specified annotation type of Reflector, and specify the classes or methods to be processed by calling the method of `Atclass () or` Atmethod () `.Finally, we can get the value of the annotation by calling the `GetValue ()" method.
Run the above code and the result will be output:
Class name: MyClass
Method name: myMethod
in conclusion:
By using the Mirror framework in the Java class library, we can more flexibly implement annotated programming.With the Mirror framework, we can process the annotation during the compiler and runtime, and provide additional metadata information in a statement.In this way, we can dynamically modify, generate, and check the code during the compilation period to achieve more flexible and scalable programming.
