(资料图)

request：获取请求数据response：设置响应数据

ServletRequest——Java提供的请求对象根接口HttpServletRequest——Java提供的对http协议封装的请求对象接口RequestFacade——tomcat实现定义类

package com.itheijma.web;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.BufferedReader;import java.io.IOException;@WebServlet("/req1")public class RequestDemo1 extends HttpServlet {    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        //String method() 获取请求方式        String method = req.getMethod();        System.out.println(method);        //String getContextPath() 获取虚拟目录（项目访问路径）        String contextPath = req.getContextPath();        System.out.println(contextPath);        //StringBuffer getRequestURL() 获取URL（统一资源定位符）        StringBuffer url = req.getRequestURL();        System.out.println(url.toString());        //String getRequestURI() 获取URI（统一资源标识符）        String uri = req.getRequestURI();        System.out.println(uri);        //String getQueryString() 获取请求参数（get方式）        String queryString = req.getQueryString();        System.out.println(queryString);        //------------        //获取请求头        String agent = req.getHeader("user-agent");        System.out.println(agent);    }    @Override    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        //获取post请求体：请求参数        // 1. 获取字符输入流        BufferedReader br = req.getReader();        // 2. 读取数据        String line = br.readLine();        System.out.println(line);    }}

package com.itheijma.web;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.util.Map;@WebServlet("/req2")public class RequestDemo2 extends HttpServlet{    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        //get请求逻辑//        System.out.println("get...");        // 1.获取所有参数的map集合        Map map = req.getParameterMap();        for (String key : map.keySet()) {            //username:zhangsan            System.out.print(key+":");            //获取值            String[] values = map.get(key);            for (String value : values) {                System.out.print(value + " ");            }            System.out.println();        }        System.out.println("----------");        // 2.根据key获取参数值，数组        String[] hobbies = req.getParameterValues("hobby");        for (String hobby : hobbies) {            System.out.println(hobby);        }        // 3. 根据key获取单个参数值        String username = req.getParameter("username");        String password = req.getParameter("password");        System.out.println(username);        System.out.println(password);    }    @Override    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        //post请求逻辑        this.doGet(req,resp);//        System.out.println("post...");//        // 1.获取所有参数的map集合//        Map map = req.getParameterMap();//        for (String key : map.keySet()) {//            //username:zhangsan//            System.out.print(key+":");////            //获取值//            String[] values = map.get(key);//            for (String value : values) {//                System.out.print(value + " ");//            }////            System.out.println();//        }////        System.out.println("----------");////        // 2.根据key获取参数值，数组//        String[] hobbies = req.getParameterValues("hobby");//        for (String hobby : hobbies) {////            System.out.println(hobby);//        }////        // 3. 根据key获取单个参数值//        String username = req.getParameter("username");//        String password = req.getParameter("password");//        System.out.println(username);//        System.out.println(password);    }}

package com.itheijma.web;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.nio.charset.StandardCharsets;/** * 中文乱码问题解决方案 */@WebServlet("/req3")public class RequestDemo3 extends HttpServlet {    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doGet(request, response);    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // 1. 解决乱码 POST 获取参数方式:getReader()读取数据流        request.setCharacterEncoding("utf-8"); //设置字符输入流的编码        // 2. 获取username        String username = request.getParameter("username");        System.out.println("解决乱码前："+username);        // 3. 解决乱码 GET 获取参数方式:getQueryString        // 乱码原因：tomcat进行url解码，默认的字符集ISO-8859-1//        // 3.1 先对乱码数据进行编码：转为字节数组//        byte[] bytes = username.getBytes(StandardCharsets.ISO_8859_1);//        // 3.2 字节数组解码//        username = new String(bytes, StandardCharsets.UTF_8);        username = new String(username.getBytes(StandardCharsets.ISO_8859_1),StandardCharsets.UTF_8);        System.out.println("解决乱码后"+username);    }}

请求转发（forward）：一种在服务器内部的资源跳转方式。请求转发特点：

package com.itheijma.web;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.nio.charset.StandardCharsets;/** * 请求转发 */@WebServlet("/req4")public class RequestDemo4 extends HttpServlet {    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doGet(request, response);    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        System.out.println("demo4");        //存储数据        request.setAttribute("msg","hello");        //请求转发        request.getRequestDispatcher("/req5").forward(request,response);    }}

req5

package com.itheijma.web;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;@WebServlet("/req5")public class RequestDemo5 extends HttpServlet {    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doGet(request, response);    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        System.out.println("demo5");        //获取数据        Object msg = request.getAttribute("msg");        System.out.println(msg);    }}

重定向：一种资源跳转的方式resp1

package com.itheima.web.response;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;@WebServlet("/resp1")public class ResponseDemo1 extends HttpServlet {    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doGet(request, response);    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        System.out.println("resp1...");//        // 重定向//        // 1. 设置状态码 302//        response.setStatus(302);//        // 2. 设置响应头 Location//        response.setHeader("Location","/tomcat-demo2/resp2");        // 简化方式完成重定向        response.sendRedirect("/tomcat-demo2/resp2");    }}

resp2

package com.itheima.web.response;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;@WebServlet("/resp2")public class ResponseDemo2 extends HttpServlet {    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doGet(request, response);    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        System.out.println("resp2...");    }}

重定向特点：

资源路径问题（什么时候加虚拟目录）浏览器使用：需要加虚拟目录服务端使用：不需要加虚拟目录

动态获取虚拟目录

//动态获取虚拟目录        String contextPath = request.getContextPath();        response.sendRedirect(contextPath + "/resp2");

package com.itheima.web.response;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;/** * 响应字符数据：设置字符数据的响应体 */@WebServlet("/resp3")public class ResponseDemo3 extends HttpServlet {    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doGet(request, response);    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        response.setContentType("text/html;charset=utf-8");        //获取字符输出流        PrintWriter writer = response.getWriter();        //content-type        //response.setHeader("content-type","text/html");        writer.write("你好");        writer.write("
aaa
");        //细节：流不需要关闭    }}

package com.itheima.web.response;import org.apache.commons.io.IOUtils;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.FileInputStream;import java.io.IOException;import java.io.PrintWriter;/** * 响应字节数据：设置字节数据的响应体 */@WebServlet("/resp4")public class ResponseDemo4 extends HttpServlet {    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doGet(request, response);    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // 1. 读取文件        FileInputStream fis = new FileInputStream("e://a.jpg");        // 2. 获取response字节输出流        ServletOutputStream os = response.getOutputStream();        // 3. 完成流的copy//        byte[] buff = new byte[1024];//        int len = 0;//        while ((len = fis.read(buff)) != -1){//            os.write(buff,0,len);//        }        IOUtils.copy(fis,os);//使用工具类        fis.close();    }}

pom文件导入工具类

            commons-io            commons-io            2.6