策略模式（简单例子）

public class huanjing {
	sageInter sage;
    public sageInter getSage() {
		return sage;
	}
	public void setSage(sageInter sage) {
		this.sage = sage;
	}
	public huanjing(sageInter sage){
    	this.sage=sage;
    }
}

 环境类

public interface sageInter {
     public int come(int a,int b);
}

 接口

public class chu implements sageInter {

	@Override
	public int come(int a, int b) {
		// TODO Auto-generated method stub
		return 1/b;
	}

}

 实现类

	public static void main(String[] args) {
		// TODO Auto-generated method stub
         jian j=new jian();
         huanjing hj=new huanjing(j);
        int s= hj.getSage().come(10, 11);
        System.out.println(s);
	}

 调用类