java-通過反射獲取目標類的屬性,方法,構造器

首先定義一個urse

package com.studay_fanshe;

public class User {
    private String uname;
    private int age;
    private int id;

    public User() {
    }

    public User(String uname, int age, int id) {
        this.uname = uname;
        this.age = age;
        this.id = id;
    }

    public String getUname() {
        return uname;
    }
    public void setUname(){
        this.uname="七月";
    }
    public void setUname(String uname) {
        this.uname = uname;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }
}

package com.studay_fanshe;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;

public class test01 {
    public static void main(String[] args) throws Exception{

        Class clazz = Class.forName("com.studay_fanshe.User");
//獲取名字
        String name = clazz.getName();//獲取包名+類名:com.studay_fanshe.User
        System.out.println(name);
        String simpleName = clazz.getSimpleName();//獲取類名:User
        System.out.println(simpleName);
 //獲取屬性
        Field[] fields = clazz.getFields();//獲取所有的公共的public修飾的屬性
        System.out.println(fields.length);
        Field[] f = clazz.getDeclaredFields();//獲取全部的屬性包括私有的
        for (Field field : f) {
          /*  private java.lang.String com.studay_fanshe.User.uname
              private int com.studay_fanshe.User.age
              private int com.studay_fanshe.User.id*/
            System.out.println(field);
        }
        //獲取指定屬性名的屬性:private java.lang.String com.studay_fanshe.User.uname
        Field uname = clazz.getDeclaredField("uname");
        System.out.println(uname);
//獲取方法
        Method[] methods = clazz.getMethods();//獲取指定類中所有的方法
        for (Method method : methods) {
            System.out.println("所有的方法:"+method);
        }
        //獲取指定類中公有的方法
        Method[] m = clazz.getDeclaredMethods();
        for (Method method : m) {
            System.out.println("public公有的方法"+method);
        }
        System.out.println("--------------------------------------------");
      /*  public void setUname(String uname) {
            this.uname = uname;
        }*/
      //有參數類型必須傳入參數類型對應的class對象
        Method setUname = clazz.getDeclaredMethod("setUname", String.class);
        System.out.println(setUname);
     /*   public void setUname(){
            this.uname="七月";
        }*/
     //沒有參數類型那么參2我們就寫null
        Method setUname1 = clazz.getDeclaredMethod("setUname", null);
        System.out.println(setUname1);
 //獲得構造器
        Constructor[] dc = clazz.getDeclaredConstructors();
        for (Constructor constructor : dc) {
            System.out.println("構造器:"+constructor);
        }
        Constructor dec = clazz.getDeclaredConstructor(String.class, int.class, int.class);
        System.out.println("指定的構造器:"+dec);
    }
}