利用反射机制通过配置文件在对象池创建对象

本文章主要内容如题。利用反射机制通过配置文件在对象池创建对象。

开始正文：

自定义两个类：

Dog：

package com.doyeden.objectpool;

public class Dog {
private String name;
private int age;

public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}

}

Cat：

package com.doyeden.objectpool;

public class Cat {
private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}

}

配置文件object_pool.properties:

##Class name and package info

Dog=com.doyeden.objectpool.Dog

Cat=com.doyeden.objectpool.Cat

下面是对象池的工厂方法。

package com.doyeden.objectpool;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;

public class ObjectPoolFactory {
// 定义一个对象池。
private Map<String, Object> objectPool = new HashMap<String, Object>();

// 创建对象，利用反射
private Object createObject(String clazzName)
throws InstantiationException, IllegalAccessException,
ClassNotFoundException {
Class<?> clazz = Class.forName(clazzName);
return clazz.newInstance();
}

// 初始化对象池
public void initPool(String fileName) throws IOException,
ClassNotFoundException, InstantiationException,
IllegalAccessException {
FileInputStream fis = null;
try {

fis = new FileInputStream(fileName);
Properties props = new Properties();
props.load(fis);
for (String name : props.stringPropertyNames()) {
objectPool.put(name, createObject(props.getProperty(name)));
}
} catch (IOException ex) {
Logger.getLogger(ObjectPoolFactory.class.getName()).log(
Level.SEVERE, null, ex);
} finally {
try {
if (fis != null) {
fis.close();
}
} catch (IOException ex) {
ex.printStackTrace();
}
}
}

// 根据名字找对象
public Object getObject(String name) {
Object o=objectPool.get(name);
System.err.println(o.getClass().getName());
return o;
}

public static void main(String[] args) throws IOException, ClassNotFoundException, InstantiationException, IllegalAccessException {
//a.properties
ObjectPoolFactory ob = new ObjectPoolFactory();
ob.initPool("object_pool.properties");
ob.getObject("Dog");
}

}


输出 结果：

com.doyeden.objectpool.Dog

可见，根据名字Dog，从配置文件得到类的包属性然后通过反射机制实例化一个Dog的类的实例，然后放入对象池中。