使用反射类、Class类获取指定的构造器并实例化对象

 package com.test;

 public class Car {

     private String brand;
     private String color;
     private int maxSpeed;

     public Car(){}

     public Car(String brand, String color, int maxSpeed) {
         super();
         this.brand = brand;
         this.color = color;
         this.maxSpeed = maxSpeed;
     }

     public String getBrand() {
         return brand;
     }

     public void setBrand(String brand) {
         this.brand = brand;
     }

     public String getColor() {
         return color;
     }

     public void setColor(String color) {
         this.color = color;
     }

     public int getMaxSpeed() {
         return maxSpeed;
     }

     public void setMaxSpeed(int maxSpeed) {
         this.maxSpeed = maxSpeed;
     }

     @Override
     public String toString() {
         return "Car [brand=" + brand + ", color=" + color + ", maxSpeed="
                 + maxSpeed + "]";
     }

 }

 package com.test;

 import java.lang.reflect.Constructor;
 import java.lang.reflect.Method;
 public class ReflectTest {

     public static Car initByDefaultConst() throws Throwable{
         //通过类转载器获取Car类对象
         //ClassLoader loader = Thread.currentThread().getContextClassLoader();
         //Class clazz = loader.loadClass("com.test.Car");
         Class clazz = Class.forName("com.test.Car");

         //构造器器参数列表
         Class[] cl = {String.class, String.class, int.class};

         //获取默认的构造器
         //Constructor cons = clazz.getDeclaredConstructor(null);

         //获取指定的带参数的构造器对象，并通过它实例化Car
         Constructor cons = clazz.getDeclaredConstructor(cl);
         //构造器参数
         Object[] ps = {"红旗H7", "黑色", 200};
         //创建实例
         Car car = (Car)cons.newInstance(ps);

         //通过反射方法设置属性
 /*        Method setBrand = clazz.getMethod("setBrand", String.class);
         setBrand.invoke(car, "红旗H7");
         Method setColor = clazz.getMethod("setColor", String.class);
         setColor.invoke(car, "黑色");
         Method setMaxSpeed = clazz.getMethod("setMaxSpeed", int.class);
         setMaxSpeed.invoke(car, 200);*/
         return car;
     }

     public static void main(String[] args) throws Throwable {
         Car car = initByDefaultConst();
         System.out.println(car);
     }

 }