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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());
}
}