UML图如下：

BDconvert、TxtConvert、XmlConvert分别为转换器接口的是实现类，其中方法为返回对应的执行接口的执行类。

具体代码如下

package Demo.Interface;

public interface Convertor {
	public Excute getExcute();
}

package Demo.Interface;

public interface Excute {
	public void Excute();
}

package Demo.ConvertImp;

import Demo.ExcuteImp.DBExcute;
import Demo.Interface.Convertor;
import Demo.Interface.Excute;

public class DBConvert implements Convertor {

	public Excute getExcute() {
		// TODO Auto-generated method stub
		return new DBExcute();
	}
		
}

package Demo.ConvertImp;

import Demo.ExcuteImp.TxtExcute;
import Demo.Interface.Convertor;
import Demo.Interface.Excute;

public class TxtConvert implements Convertor {

	public Excute getExcute() {
		// TODO Auto-generated method stub
		return new TxtExcute();
	}
		
}

package Demo.ConvertImp;


import Demo.ExcuteImp.XmlExcute;
import Demo.Interface.Convertor;
import Demo.Interface.Excute;

public class XmlConvert implements Convertor {

	public Excute getExcute() {
		// TODO Auto-generated method stub
		return new XmlExcute();
	}
		
}
package Demo.ExcuteImp;

import Demo.Interface.Excute;

public class DBExcute implements Excute{

	public void Excute() {
		// TODO Auto-generated method stub
		System.out.println("BD Excuting");
		
	}

	

}
package Demo.ExcuteImp;


import Demo.Interface.Excute;

public class TxtExcute implements  Excute {

	public void Excute() {
		// TODO Auto-generated method stub
		System.out.println("Txt Excuting");

	}


}
package Demo.ExcuteImp;

import Demo.Interface.Excute;

public class XmlExcute implements Excute {

	public void Excute() {
		// TODO Auto-generated method stub
		System.out.println("Xml Excuting");
	}

}
package Demo.Test;

import Demo.ConvertImp.DBConvert;
import Demo.ConvertImp.TxtConvert;
import Demo.ConvertImp.XmlConvert;
import Demo.ExcuteImp.DBExcute;
import Demo.ExcuteImp.TxtExcute;
import Demo.ExcuteImp.XmlExcute;

public class TestALl {
	public static void main(String[] args) {
		DBConvert convert1 =new DBConvert();
		DBExcute dbExcute=(DBExcute) convert1.getExcute();
		dbExcute.Excute();
		TxtConvert convert2 =new TxtConvert();
		TxtExcute txtExcute=(TxtExcute) convert2.getExcute();
		txtExcute.Excute();
		XmlConvert convert3 = new XmlConvert();
		XmlExcute xmlExcute=(XmlExcute)convert3.getExcute();
		xmlExcute.Excute();
	}

}