The important role and technical principle analysis of the JBoss Reflection framework in the Java class library
The important role and technical principle analysis of the JBoss Reflection framework in the Java class library
Jboss Reflection is a framework based on the Java reflection mechanism, which plays an important role in the Java library.This article will introduce the important role and technical principles of the JBoss Reflection framework in the Java class library, and provide the corresponding Java code example.
1. The important role of the JBoss Reflection framework
1. Dynamic creation object: The Reflection framework can dynamically create a Java object during runtime.This provides a very convenient way for the application of dynamic creation objects in some cases, such as factory design models.
The following is a simple example that shows how to use the Reflection framework to create objects dynamically:
import java.lang.reflect.Constructor;
public class ReflectionDemo {
public static void main(String[] args) {
try {
Class<?> clazz = Class.forName("com.example.MyObject");
Constructor<?> constructor = clazz.getConstructor();
Object obj = constructor.newInstance();
System.out.println(obj);
} catch (Exception e) {
e.printStackTrace();
}
}
}
class MyObject {
public MyObject() {
System.out.println ("MyObject was created!");
}
}
2. Visit private members: The Reflection framework allows us to access and call private members in categories, including private fields, private methods, and private structure functions.This is very useful for the scenes that need to dynamically modify the private members, such as unit testing and framework development.
The following is an example that shows how to use the Reflection framework to access and call private members:
import java.lang.reflect.Field;
import java.lang.reflect.Method;
public class ReflectionDemo {
public static void main(String[] args) {
try {
Class<?> clazz = Class.forName("com.example.MyClass");
// Visit private fields
Field privateField = clazz.getDeclaredField("privateField");
privateField.setAccessible(true);
privateField.set(null, "Changed Value");
// Call the private method
Method privateMethod = clazz.getDeclaredMethod("privateMethod");
privateMethod.setAccessible(true);
privateMethod.invoke(null);
} catch (Exception e) {
e.printStackTrace();
}
}
}
class MyClass {
private static String privateField = "Original Value";
private static void privateMethod() {
System.out.println ("Private methods have been called!"););
}
}
3. Dynamic proxy: The Reflection framework enables us to easily implement the dynamic proxy mode.By using the PROXY class provided by the Reflection framework, we can dynamically create proxy objects and add additional logic to the proxy object.This is very useful for some situations that need to generate proxy categories at runtime, such as AOP (programming -oriented programming) and remote calls.
The following is an example that shows how to use the Reflection framework to achieve dynamic proxy:
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
public class ReflectionDemo {
public static void main(String[] args) {
Target target = new TargetImpl();
Target proxy = (Target) Proxy.newProxyInstance(
target.getClass().getClassLoader(),
target.getClass().getInterfaces(),
new CustomInvocationHandler(target));
proxy.doSomething();
}
}
interface Target {
void doSomething();
}
class TargetImpl implements Target {
public void doSomething() {
System.out.println ("The target object executes business methods!"););
}
}
class CustomInvocationHandler implements InvocationHandler {
private Object target;
public CustomInvocationHandler(Object target) {
this.target = target;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
System.out.println ("Extreme logic added by the agent object!"););
return method.invoke(target, args);
}
}
Second, analysis of the technical principles of JBoss Reflection framework
1. Get the Class object: The first step of the Reflection framework is to obtain the Class Class object through the full -limited name of the class.This process can obtain the Class object by calling the class.Forname () method, or through the object of the object of the object.
2. Members of obtaining class: The Reflection framework uses methods provided by Class objects, such as GetFields (), GetDeclaredFields (), GetMethods (), GetDeClaredMethods (), etc., to obtain class members.These methods can be used to obtain fields, methods, constructors, etc. of class.
3. Modify private attributes: The Reflection framework is set to TRUE through the Setaccessible () method to set the accessability of private attributes to TRUE, and then use the set () method provided by the FIELD object to modify the value of the private attribute.
4. Calling method: Reflection framework uses the inf () method provided by the Method object, and calls the method by passing the object and corresponding parameters.
5. Create objects: The newInstance () method provided by the Reflection framework is provided by the Constructor object, creating a new object by creating a new object by constructing a function or a participation function.
The above is the important role and technical analysis of the JBoss Reflection framework in the Java class library.The flexibility and powerful functions of the Reflection framework make it one of the indispensable tools in Java development.
references:
1. Oracle. "Java Reflection". https://docs.oracle.com/javase/tutorial/reflect/.
2. JBoss Community. "JBoss Reflection". https://docs.jboss.org/reflection/
