ListBookServlet.java中为什么无法解析 'HttpServletResponse' 中的方法 'getWriter'
时间: 2024-01-23 09:02:02 浏览: 127
在Java中,`HttpServletResponse`是`javax.servlet.http`包中的类,它代表一个HTTP响应。`getWriter()`是`ServletResponse`接口的一个方法,它用于获取一个`PrintWriter`对象,可以用来向客户端发送字符数据。因此,如果您在`ListBookServlet.java`中无法解析`getWriter()`方法,有可能是因为您没有正确导入`javax.servlet.http.HttpServletResponse`类。
请确保您在`ListBookServlet.java`文件的开头添加了以下导入语句:
```java
import javax.servlet.http.HttpServletResponse;
```
如果您已经添加了这个导入语句,但仍然无法解析`getWriter()`方法,请检查您的编译环境和类路径是否正确配置。
相关问题
ListBookServlet.java中为什么无法解析 'HttpServletResponse' 中的方法 'setContentType'
通常情况下,无法解析 HttpServletResponse 中的 setContentType 方法是因为没有正确导入 javax.servlet.http.HttpServletResponse 类。请确保在 ListBookServlet.java 文件中包含了以下导入语句:
```java
import javax.servlet.http.HttpServletResponse;
```
如果已经导入了该类但仍然出现问题,请检查是否有任何编译器错误或警告,以及是否正确配置了 Web 应用程序的 classpath。
httpservletresponse.getwriter
httpservletresponse.getwriter是一个方法,用于获取一个PrintWriter对象,该对象可以用于向客户端发送文本响应。在使用该方法之前,必须先使用httpservletresponse.setContentType方法设置响应的内容类型。
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package com.test.servlet; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import com.test.bean.Cart; import com.test.dao.CartDao; /** * Servlet implementation class DelCartServlet */ @WebServlet("/Servlet/DelCartServlet") public class DelCartServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public DelCartServlet() { super(); // TODO Auto-generated constructor stub } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setCharacterEncoding("utf-8"); response.setHeader("Content-type","text/html;charset=utf-8") ; String gid=request.getParameter("gid"); if(gid!=null) { HttpSession session=request.getSession(); Cart cart=(Cart)session.getAttribute("cart"); if(cart!=null) { CartDao cartdao=new CartDao(); cartdao.delGoods(cart, Integer.parseInt(gid)); session.setAttribute("cart", cart); response.getWriter().println("删除成功"); }else { response.getWriter().println("删除失败"); } }else { response.getWriter().println("参数不正确"); } response.getWriter().println("查看购物车"); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub doGet(request, response); } } 修改删除功能,在购物车物品数量大于1的情况下点击“删除”时减少1个,等于1时删除此项商品;


import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.sql.SQLException; @WebServlet("/update") public class update extends HttpServlet { @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setContentType("text/html;charset=utf-8"); String id = req.getParameter("id"); String username = req.getParameter("username"); String password = req.getParameter("password"); UsersDao usersDao = new UsersDao(); User user = new User(); user.setUsername(username); user.setPassword(password); user.setId(Integer.valueOf(id)); try { if (usersDao.update(user)) { resp.getWriter().println("修改成功"+"返回主页"); } else { resp.getWriter().println("修改失败"+"返回主页"); } } catch (SQLException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); } } }

大致讲解一下代码:6.BuyPhoneServlet: package Session01; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.io.PrintWriter; import java.util.ArrayList; @WebServlet("/buyPhoneServlet") public class BuyPhoneServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setContentType("text/html;charset=utf-8"); PrintWriter out=resp.getWriter(); String idstr=req.getParameter("id"); int id=Integer.parseInt(idstr); ArrayList ckDB= PhoneDb.getAll(); Phone ck=ckDB.get(id-1); out.println("您购买的"+ck.getName()+"手机下单成功。"); out.println("继续选购"); } }





