java web 里面在xml里面配置servlet时出现了如下错误

刚开始是这样的

后来又刷新了一遍

我已经快疯了，网上说是类名不对，可是我的是对的啊
package MyServelet;

import java.io.IOException;

import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class MyFirstServelet implements Servlet
{

@Override
public void destroy() {
    // TODO Auto-generated method stub
    System.out.println("destroy");
}

@Override
public ServletConfig getServletConfig() {
    // TODO Auto-generated method stub
    System.out.println("getServletConfig");
    return null;
}

@Override
public String getServletInfo() {
    // TODO Auto-generated method stub
    System.out.println("getServletInfo");
    return null;
}

@Override
public void init(ServletConfig arg0) throws ServletException {
    // TODO Auto-generated method stub
    System.out.println("init");
}

@Override
public void service(ServletRequest arg0, ServletResponse arg1) throws ServletException, IOException {
    // TODO Auto-generated method stub
    System.out.println("service");
}

public MyFirstServelet()
{
System.out.println("我成功了。。。。。");
}
}

<?xml version="1.0" encoding="UTF-8"?>


hello

<servlet-class>MyServelet.MyFirstServelet</servlet-class>

hello
/happy

项目clean下，可能是编译类文件没有发布过去。

http://bbs.csdn.net/topics/390812285

<?xml version="1.0" encoding="UTF-8"?>

hello
MyServelet.MyFirstServelet

hello
/happy

xml中配置的时候
类名写全包名+类名

映射的url把工程名加上/SP01/happy