COMMONS BeANUTILS CORE Framework of the implementation principles in the Java class library
Commons Beanutils Core framework is a tool widely used in the Java library. It provides a convenient way to operate the attributes of the Java object.This article will explore the implementation principle of the framework and explain the Java code example.
The implementation principle of the Beanutils framework is mainly based on the reflection mechanism.Reflection is a dynamic acquisition and operation information in the Java language.BEANUTILs can dynamically obtain and set the attributes of the Java object during the use of the reflex mechanism.
First, Beanutils uses a reflection mechanism to obtain all the attributes of the target Java class.It traverses the method of the target class to determine whether it is a legal attribute Getter or Setter method by analyzing the method name.By obtaining the attribute name and the Getter and Setter method corresponding to, Beanutils obtained all the attribute information of the object.
Then, by calling the Getter method, the value of the attribute can be obtained from the target object.Beanutils will call the getter method of the target object and return the value of the attribute to the caller.
Similarly, the attribute value of the target object can be set by calling the setter method.Beanutils will pass the attribute value as the parameter to the setter method of the target object, and call the method through reflection to set the new value to the target object.
In addition, Beanutils also provides some other functions, such as replication attributes, mapping attributes, etc.By speculating the source and target objects, Beanutils can copy the attribute value of the source object to the target object.In this process, Beanutils uses the reflex mechanism to obtain the attribute value of the source object, and copy the attribute value to the target object through the setter method of the target object.
Below the Java code example to demonstrate the use of the Beanutils framework:
import org.apache.commons.beanutils.BeanUtils;
public class ExampleBean {
private String name;
private int age;
// Getter and Setter method omitted
public static void main(String[] args) {
ExampleBean sourceBean = new ExampleBean();
sourceBean.setName("John");
sourceBean.setAge(30);
ExampleBean targetBean = new ExampleBean();
try {
System.out.println("Before copy:");
System.out.println("Target name: " + targetBean.getName());
System.out.println("Target age: " + targetBean.getAge());
BeanUtils.copyProperties(targetBean, sourceBean);
System.out.println("After copy:");
System.out.println("Target name: " + targetBean.getName());
System.out.println("Target age: " + targetBean.getAge());
} catch (Exception e) {
e.printStackTrace();
}
}
}
In the above examples, we created a class called Examplebean, with the name and Age attributes, and the corresponding Getter and Setter method.We then created two EXAMPLEBEAN objects SourceBean and TargetBean.
By calling Beanutils' CopyProperties method, we copy the attribute value of SourceBean to TargetBean.This method will automatically call the reflection mechanism and set the attribute value in SourceBean to targetBean.
By running the above example, we can see that the attribute value of TargetBean before copying the attribute is empty.After copying the attribute, the attribute value of TargetBean is the same as SourceBean.
By analyzing the above examples, we can understand that the implementation principle of the Commons Beanutils Core framework is mainly based on the reflection mechanism.It provides a convenient way to operate the attribute value of the object by dynamically obtaining and setting the attributes of the Java object.This allows developers to operate the Java object more conveniently and improve the flexibility and maintenance of the code.
