java反射系列六之调用属性与方法

调用指定属性

package reflect;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;

public class TestFiled {
    public static void main(String[] args) throws Exception {
        TestFiled t = new TestFiled();
        t.test3();
    }
    //调用运行时类中的指定的属性
    public void test3() throws Exception {
        Class clazz = Person.class;
        //1.获取指定的属性
        //getField(String fieldName):获取运行时类中声明为public的指定属性名为name的属性
        Field name = clazz.getField("name");
        //2.创建运行时类的对象
        Person p =(Person) clazz.newInstance();
        System.out.println(p);
        //3.将运行时类的指定的属性赋值
        name.set(p, "巫妖果子");
        System.out.println(p);
        
        System.out.println();
        //getDeclaredField(String fieldName):获取运行时类中声明为private的指定属性名为age
        Field age = clazz.getDeclaredField("age");
        //设置此声明private属性可被操作
        age.setAccessible(true);
        age.set(p, 20);
        System.out.println(p);
    }
}

调用指定方法

package reflect;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

public class TestMethod {
    public static void main(String[] args) throws Exception {
        TestMethod t = new TestMethod();
        t.test2();
    }
    //调用运行时类的指定方法
    public void test2() throws Exception {
        Class clazz = Person.class;
        //getMethod(String methodName,class...params):获取运行时类中声明为public的指定方法
        Method m = clazz.getMethod("show");
        //实例化运行时类clazz的对象
        Person p = (Person)clazz.newInstance();
        //调用方法
        Object returnValue = m.invoke(p);
        //打印返回类型
        System.out.println(returnValue);
        
        Method m1 = clazz.getMethod("toString");
        Object returnValue1 = m1.invoke(p);
        System.out.println(returnValue1);
        
        //静态方法的调用
        Method m3 = clazz.getMethod("info");
        //类名.调用
        m3.invoke(Person.class);
        
        //getDeclaredMethod(String methodName,Class..params):获取运行时类声明的方法
        Method m4 = clazz.getDeclaredMethod("display",String.class,Integer.class);
        m4.setAccessible(true);
        Object retuenValue2 = m4.invoke(p, "Chinese",10);
        System.out.println(retuenValue2);
    }
}

调用构造器

package reflect;

import java.lang.reflect.Constructor;

public class TestConstructor {
    public static void main(String[] args) throws Exception {
        TestConstructor T = new TestConstructor();
        T.test2();
    }
    //调用指定的构造器
    public void test2() throws Exception {
        String className = "reflect.Person";
        Class clazz = Class.forName(className);
        
        Constructor cons = clazz.getDeclaredConstructor(String.class,int.class);
        cons.setAccessible(true);
        Person p = (Person)cons.newInstance("巫妖果子",20);
        System.out.println(p);
        
    }
}