[Java基础]反射练习之越过泛型检查，运行配置文件制定内容

Posted 2021-08-15 Wecccccccc

代码如下:

package ReflectTest01;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;

public class ReflectTest01 {
    public static void main(String[] args) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        ArrayList<Integer> array = new ArrayList<Integer>();

        Class<? extends ArrayList> c = array.getClass();
        Method m = c.getMethod("add", Object.class);

        m.invoke(array,"hello");

        m.invoke(array,"world");

        m.invoke(array,"java");
        
        System.out.println(array);

    }

}

测试结果:

text文件:

 className = ReflectDemoPack.Student
        methodName = study

代码如下:

package ReflectDemoPack;

public class Teacher {
    public void teach()
    {
        System.out.println("用爱成就学员");

    }

}

package ReflectDemoPack;

public class Student {
    public void study()
    {
        System.out.println("好好学习，天天向上");
    }
}

package ReflectDemoPack;

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Properties;

public class ReflectTest02 {
    public static void main(String[] args) throws IOException, NoSuchMethodException, ClassNotFoundException, InvocationTargetException, InstantiationException, IllegalAccessException {
//        Student s = new Student();
//        s.study();

//        Teacher t = new Teacher();
//        t.teach();

        /*
        class.txt
        className = xxx
        methodName = xxx
         */

        //加载数据
        Properties prop = new Properties();
        FileReader fr = new FileReader("D:\\\\javaTEST\\\\class.txt");
        prop.load(fr);
        fr.close();

        /*
         className = ReflectDemoPack.Student
        methodName = study

         */

        String className = prop.getProperty("className");
        String methodName = prop.getProperty("methodName");

        Class<?> c = Class.forName(className);

        Constructor<?> con = c.getConstructor();

        Object obj = con.newInstance();
        Method m = c.getMethod(methodName);
        m.invoke(obj);



    }
}