编写servlet的相关问题

(1)
response.setContentType("text/html;charset=utf-8");
PrintWriter writer=response.getWriter();
writer.println("<script>alert('用户名或密码不正确！');window.location.href='adminlogin.jsp';</script>");

response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
out.write("<script language='javascript'>alert('操作失败！');" +"window.location.href='"+request.getContextPath()+"/admin/addprice.jsp?id="+id+"';</script>");