简易版Spring Ioc (转载)

package com.ioc.service;

import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

/**
* @author lei 2011-8-22
*
* 简单实现了一下Spring的IOC，理解IOC原理，多使用面向接口编程
*
*/
public class BeanFactory {

private Map<String, String> beanDefinitions;

BeanFactory(String source) {
this.register(source);
}

public void register(String source) {
InputStream in = this.getClass().getResourceAsStream(source);
Properties p = new Properties();
try {
p.load(in);
in.close();
beanDefinitions = new HashMap<String, String>();
for (Map.Entry<Object, Object> entry : p.entrySet()) {
beanDefinitions.put(entry.getKey().toString(), entry.getValue().toString());
}
} catch (IOException e) {
e.printStackTrace();
}
}

public Object getBean(String name) {
try {
String value = beanDefinitions.get(name);
return Class.forName(value).newInstance();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
return null;
}

public static void main(String[] args) {
BeanFactory factory = new BeanFactory("hello.properties");
MessageWrite write = (MessageWrite) factory.getBean("messageWrite");
MessageSource source = (MessageSource) factory.getBean("messageSource");
write.write(source.getMessage());
}

}

interface MessageSource {
public String getMessage();
}
/**
* message
* @author lei
* 2011-8-22
*/
class SimpleMessageSource implements MessageSource {

@Override
public String getMessage() {
return "hello world";
}
}
/**
* 输出Service
* @author lei
* 2011-8-22
*/
interface MessageWrite {
public void write(String str);
}

class SimpleMessageWrite implements MessageWrite {
public void write(String str) {
System.out.println(str);
}
}
/**
* 附上hello.properties
* /messageWrite=com.ioc.service.SimpleMessageWrite
* /messageSource=com.ioc.service.SimpleMessageSource
*
*/