InternalResourceViewResolver问题？？

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" name="viewResolver">
        <property name="prefix" value="/WEB-INF/views/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>

@Controller
public class ResponseController {
    @RequestMapping("/response1")
    public String response1(){
        System.out.println("response1");
        return "index";  
    }
}

以上代码报错
以下代码能通过
这是为啥？
"/WEB-INF/views/" 后面的"/"加在两个地方不都一样吗？

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" name="viewResolver">
        <property name="prefix" value="/WEB-INF/views"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>

@Controller
public class ResponseController {
    @RequestMapping("/response1")
    public String response1(){
        System.out.println("response1");
        return "/index";  
    }
}

学会怎么debug吧，这种细微的东西