今天遇到一个很低级的错误，就是一直提示response没有声明，没有初始化，结果发现，参数位置的参数写错了。
比如：
public void service(ServletRequest arg0, ServletResponse arg1)
throws ServletException, IOException {
// TODO Auto-generated method stub
String servletName = servletConfig.getServletName();
response.setContentType("text/html"); //此句错
PrintWriter writer = arg1.getWriter();
writer.print("<html><head></head>"+
"<body>hello from "+servletName+
"</body></html>");
}
正解：
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
String servletName = servletConfig.getServletName();
response.setContentType("text/html");
PrintWriter writer = arg1.getWriter();
writer.print("<html><head></head>"+
"<body>hello from "+servletName+
"</body></html>");
}