Understanding BeanUtils.populate() in Java

1 year ago
Emily Johnson
2 minutes

In Java, the BeanUtils.populate() method is a method in the Apache Commons BeanUtils library that copies the property values of a Map into a JavaBean object.

More specifically, the populate() method takes two parameters: the target object and the source Map object. It uses reflection to iterate through the key-value pairs of the source Map object, with the keys being used as the property names of the JavaBean object and the values as the property values, copying these values into the target object.

This method is mainly used to copy property values between different objects. By using the populate() method, you can easily copy property values from a Map object to a JavaBean object without manually setting each property value. This is very useful for scenarios such as handling form submissions and parsing configuration files.

Here is an example code that demonstrates how to use the populate() method to copy the attribute values of a Map into a JavaBean object:

import org.apache.commons.beanutils.BeanUtils;

public class Main {
    public static void main(String[] args) throws Exception {
        // 创建一个JavaBean对象
        Person person = new Person();

        // 创建一个Map对象，并设置属性值
        Map<String, Object> properties = new HashMap<>();
        properties.put("name", "John Doe");
        properties.put("age", 25);

        // 调用populate()方法将属性值复制到JavaBean对象中
        BeanUtils.populate(person, properties);

        // 打印JavaBean对象的属性值
        System.out.println(person.getName()); // 输出：John Doe
        System.out.println(person.getAge());  // 输出：25
    }
}

class Person {
    private String name;
    private int age;

    // 省略getter和setter方法
}

In the example above, the populate() method copies the property values from the Map object ‘properties’ into the ‘person’ object. As a result, the ‘name’ property of the person object is set to “John Doe” and the ‘age’ property is set to 25.

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