利用反射读取配置文件中的具体实现类

该博客用于简单模拟如何利用反射读取配置文件中的具体实现类，一般框架的底层实现原理就是如此的。

1、配置文件config.properties文件中的代码：

#className=java.util.ArrayList
className=java.util.HashSet

2、实例类ReflectPoint.java中的代码

package cn.sunft.day01.reflect;

/**
 * 定义一个点的类,供反射测试用
 * @author sunft
 *
 */
public class ReflectPoint {
	
	private int x;
	public int y;
	public String str1 = "ball";
	public String str2 = "basketball";
	public String str3 = "itcast";
	
	
	public ReflectPoint(int x, int y) {
		super();
		this.x = x;
		this.y = y;
	}

	public int getX() {
		return x;
	}

	public void setX(int x) {
		this.x = x;
	}

	public int getY() {
		return y;
	}

	public void setY(int y) {
		this.y = y;
	}
	
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + x;
		result = prime * result + y;
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		ReflectPoint other = (ReflectPoint) obj;
		if (x != other.x)
			return false;
		if (y != other.y)
			return false;
		return true;
	}

	@Override
	public String toString() {
		return str1 + ":" + str2 + ":" + str3;
	}
	
}

3、测试类ReflectCollection.java中的代码

package cn.sunft.day01.reflect;

import java.io.FileInputStream;
import java.io.InputStream;
import java.util.Collection;
import java.util.Properties;

/**
 * 
 * @author sunft
 *
 */
public class ReflectCollection {

	public static void main(String[] args) throws Exception {
		InputStream ips = new FileInputStream("config.properties");
		Properties props = new Properties();
		props.load(ips);
		ips.close();
		String className = props.getProperty("className");
		//这里默认会调用无参数的构造方法
		Collection collections = (Collection) Class.forName(className)
				.newInstance();
		
		ReflectPoint pt1 = new ReflectPoint(3, 3);
		ReflectPoint pt2 = new ReflectPoint(5, 5);
		ReflectPoint pt3 = new ReflectPoint(3, 3);
		
		collections.add(pt1);
		collections.add(pt2);
		collections.add(pt3);
		collections.add(pt1);
		
		System.out.println(collections.size());
	}

}