综合案例
⦁ 优化Servlet
⦁ 目的
减少Servlet的数量，现在是一个功能一个Servlet，将其优化为一个模块一个Servlet，相当于在数据库中一张表对应一个Servlet，在Servlet中提供不同的方法，完成用户的请求。
⦁ BaseServlet编写：
public class BaseServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//System.out.println("baseServlet的service方法被执行了...");
//完成方法分发
//1.获取请求路径
String uri = req.getRequestURI(); // /travel/user/add
System.out.println("请求uri:"+uri);// /travel/user/add
//2.获取方法名称
String methodName = uri.substring(uri.lastIndexOf('/') + 1);
System.out.println("方法名称："+methodName);
//3.获取方法对象Method
//谁调用我？我代表谁
System.out.println(this);//UserServlet的对象cn.itcast.travel.web.servlet.UserServlet@4903d97e
try {
//获取方法
Method method = this.getClass().getMethod(methodName, HttpServletRequest.class, HttpServletResponse.class);
//4.执行方法
//暴力反射
//method.setAccessible(true);
method.invoke(this,req,resp);
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
}
}
⦁ UserServlet改写
将之前的Servlet实现的功能，抽取到UserServlet中的不同方法中实现，并且将UserService创建抽取到成员变量位置
@WebServlet("/user/*") // /user/add /user/find
public class UserServlet extends BaseServlet {
//声明UserService业务对象
private UserService service = new UserServiceImpl();
/**
* 注册功能
* @param request
* @param response
* @throws ServletException
* @throws IOException
*/
public void regist(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//验证校验
String check = request.getParameter("check");
//从sesion中获取验证码
HttpSession session = request.getSession();
String checkcode_server = (String) session.getAttribute("CHECKCODE_SERVER");
session.removeAttribute("CHECKCODE_SERVER");//为了保证验证码只能使用一次
//比较
if(checkcode_server == null || !checkcode_server.equalsIgnoreCase(check)){
//验证码错误
ResultInfo info = new ResultInfo();
//注册失败
info.setFlag(false);
info.setErrorMsg("验证码错误");
//将info对象序列化为json
ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(info);
response.setContentType("application/json;charset=utf-8");
response.getWriter().write(json);
return;
}
//1.获取数据
Map<String, String[]> map = request.getParameterMap();
//2.封装对象
User user = new User();
try {
BeanUtils.populate(user,map);
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
//3.调用service完成注册
//UserService service = new UserServiceImpl();
boolean flag = service.regist(user);
ResultInfo info = new ResultInfo();
//4.响应结果
if(flag){
//注册成功
info.setFlag(true);
}else{
//注册失败
info.setFlag(false);
info.setErrorMsg("注册失败!");
}
//将info对象序列化为json
ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(info);
//将json数据写回客户端