Request

Request继承体系

Request获取请求数据

获取请求数据

通用方式获取请求参数

@WebServlet("/req1")
public class req1 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//System.out.println("get...");// 获取所有参数的Map集合Map parameterMap = req.getParameterMap();for (String s : parameterMap.keySet()) {System.out.print(s+":");String[] strings = parameterMap.get(s);for (String string : strings) {System.out.print(string+" ");}System.out.println();}// 根据key获取参数值。数组System.out.println("----------------");String[] hobbies = req.getParameterValues("hobby");for (String hobby : hobbies) {System.out.println(hobby);}// 根据key获取单个参数值System.out.println("-------------------");String username = req.getParameter("username");String password = req.getParameter("password");System.out.println(username);System.out.println(password);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {this.doGet(req,resp);}
}

请求参数中文乱码

@WebServlet("/req2")
public class req2 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String username = request.getParameter("username");username = new String(username.getBytes(StandardCharsets.ISO_8859_1),StandardCharsets.UTF_8);System.out.println(username);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {request.setCharacterEncoding("UTF-8");this.doGet(request, response);}
}

Request请求转发

Response

Response设置响应数据功能介绍

Response完成重定向

目录问题

动态获取虚拟目录：

Response响应字符数据

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// 设置解析方式,和字符集//response.setHeader("content-type","text/html");response.setContentType("text/html;charset=utf-8");// 获取流PrintWriter writer = response.getWriter();writer.write("
侯一鸣
");
}

Response响应字节数据

    @Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// 读取文件FileInputStream fis = new FileInputStream("d://桌面/1.png");// 获取response的输出流ServletOutputStream os = response.getOutputStream();// 完成流的拷贝
//        byte[] bytes = new byte[1024];
//        int len = 0;
//        while ((len = fis.read(bytes)) != -1){
//            os.write(bytes,0,len);
//        }IOUtils.copy(fis,os);fis.close();}

案例

用户登录

编写LoginServlet方法

@WebServlet("/loginServlet")
public class loginServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String username = request.getParameter("username");String password = request.getParameter("password");//调用maybatis查询String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);SqlSession sqlSession = sqlSessionFactory.openSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);User user = mapper.select(username, password);sqlSession.close();// 判断response.setContentType("text/html;charset=utf-8");PrintWriter writer = response.getWriter();if(user != null){writer.write("登陆成功");}else{writer.write("登陆失败");}}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

用户注册

registerServlet

@WebServlet("/registerServlet")
public class registerServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String username = request.getParameter("username");String password = request.getParameter("password");User user = new User();user.setUsername(username);user.setPassword(password);String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);SqlSession sqlSession = sqlSessionFactory.openSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);User u = mapper.selectByUsername(username);response.setContentType("text/html;charset=utf-8");PrintWriter writer = response.getWriter();if (u == null){mapper.add(user);sqlSession.commit();// 增删改需要提交事务sqlSession.close();writer.write("注册成功");}else{writer.write("用户名已存在");}}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request, response);}
}

SqlSessionFactory工具类抽取

package com.houyiming.util;import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;import java.io.IOException;
import java.io.InputStream;public class SqlSessionFactoryUtils {private static SqlSessionFactory sqlSessionFactory;static {// 静态代码块会随着类的加载自动执行，且只执行一次try {String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);} catch (IOException e) {e.printStackTrace();}}public static SqlSessionFactory getSqlSessionFactory(){return sqlSessionFactory;}
}

可以用一行代码代替原来的三行

// 原来的三行
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);// 新的一行
SqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtils.getSqlSessionFactory();
= "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);// 新的一行
SqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtils.getSqlSessionFactory();