JAVA高级基础（57）---反射+properties

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反射在实际开发中的应用

properties:属性文件
               文件中的内容：以键值对的形式存在
                键和值都是以字符串的形式存在

clas.properties：

username = root
password=root
className = org.lanqiao.reflect.demo.Student

package org.lanqiao.reflect.demo2;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

public class TestPro {
	public static void main(String[] args) throws IOException {
		//创建properties对象
		Properties pro  = new Properties();
		//以流的形式加载属性配置文件
		//InputStream is = new FileInputStream(new File("clas.properties"));
		//通过类加载器来获取配置文件的输入流
		InputStream is = TestPro.class.getClassLoader().getResourceAsStream("clas.properties");
		pro.load(is);
		String username = pro.getProperty("username");
		String password = pro.getProperty("password");
		System.out.println(username +"---"+ password);
		
		
		
	}
}

package org.lanqiao.reflect.demo2;

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

/*
 * 返回某一个类的对象
 * 该类可以由其他程序员来指定
 */
public class ReturnObj {
	
	public static  Object returnObj() throws ClassNotFoundException, NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, IOException {
		
		Properties pro = new Properties();
		pro.load(ReturnObj.class.getClassLoader().getResourceAsStream("clas.properties"));
		String className = pro.getProperty("className");
		
		Class clazz = 	Class.forName(className);
		Constructor con = clazz.getConstructor();
			
		Object obj = con.newInstance();
			
		return obj;
	}
	
}

package org.lanqiao.reflect.demo2;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;

public class Test {
	public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, IOException {
		Object obj  = ReturnObj.returnObj();
		System.out.println(obj.getClass()); 
	}
}