What is the function of BeanUtils.populate?

The purpose of the BeanUtils.populate method is to automatically fill the values of key-value pairs in a Map into the corresponding properties of a JavaBean object.

In particular, this method will iterate through all key-value pairs in the Map, then by using reflection, it will locate the corresponding property in the JavaBean and assign the value from the corresponding key in the Map to the property. If the property’s type does not match, it will attempt to perform a type conversion.

For instance, consider a JavaBean object named Person:

public class Person {
    private String name;
    private int age;

    // 省略构造函数和getter/setter方法
}

You can use the BeanUtils.populate method to populate the values from a Map into a Person object.

Map<String, Object> map = new HashMap<>();
map.put("name", "Alice");
map.put("age", 25);

Person person = new Person();
BeanUtils.populate(person, map);

System.out.println(person.getName()); // 输出：Alice
System.out.println(person.getAge()); // 输出：25

In the above example, the values associated with the “name” and “age” keys in the Map were used to populate the name and age properties of the Person object using the BeanUtils.populate method. The result displayed is the values of the corresponding keys in the Map.

It’s important to note that the BeanUtils.populate method automatically handles type conversion. However, if the property’s type is not a basic type in JavaBean (such as String, int, etc.) but a custom type, then it is necessary to ensure that the type has a constructor that accepts a String parameter, or register a corresponding type converter.