获取类的构造方法

方法介绍

public class Users {
    private String username;
    private int userage;
    public Users(){
    }
    public Users(String username,int userage){
        this.userage=userage;
        this.username=username;
    }
    private Users(int userage){
        this.userage=userage;
    }
    public Users(String username){
        this.username=username;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public int getUserage() {
        return userage;
    }
    public void setUserage(int userage) {
        this.userage = userage;
    }
}

方法的使用

import java.lang.reflect.Constructor;

public class GetConstructor {
    public static void main(String[] args) throws Exception {
        Class clazz=Users.class;
        Constructor[] arr = clazz.getDeclaredConstructors(); //返回所有构造方法
        for(Constructor c:arr){
            System.out.println(c);
        }
        System.out.println("---------------");
        Constructor[] arr_1 = clazz.getConstructors();  //仅返回public类构造方法
        for(Constructor c:arr_1){
            System.out.println(c);
        }
        System.out.println("-------------------");
        Constructor c1 = clazz.getDeclaredConstructor(int.class);  //返回指定构造方法，包含private类型的构造方法
        System.out.println(c1);
        System.out.println("------------------");
        Constructor c2 = clazz.getConstructor(null);//返回指定构造方法，不包含private类型的构造方法
        System.out.println(c2);
    }
}

通过构造方法创建对象

import java.lang.reflect.Constructor;

public class GetConstructor_2 {
    public static void main(String[] args) throws Exception {
        Class clazz = Users.class;
        Constructor constructor = clazz.getConstructor(String.class,int.class);
        Object o = constructor.newInstance("laogeng",25);
        Users users =(Users)o;
        System.out.println(users.getUsername()+"\t"+users.getUserage());
    }
}