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<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <!--配置Servlet-->
    <servlet>
        <servlet-name>demo01</servlet-name>
        <servlet-class>demo01_servlet.Demo01Servlet</servlet-class>
    </servlet>
    <!--Servlet映射-->
    <servlet-mapping>
        <servlet-name>demo01</servlet-name>
        <!-- 访问路径，过滤器中这个地方是拦截路径 -->
        <url-pattern>/demo01</url-pattern>
    </servlet-mapping>
</web-app>

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/**
 * Servlet快速入门
 * @author https://github.com/meethigher
 */
public class Demo01Servlet implements Servlet {
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {

    }

    @Override
    public ServletConfig getServletConfig() {
        return null;
    }

    /**
     * 提供服务的方法
     * @param servletRequest
     * @param servletResponse
     * @throws ServletException
     * @throws IOException
     */
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("Hello Servlet");
    }

    @Override
    public String getServletInfo() {
        return null;
    }

    @Override
    public void destroy() {

    }
}

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public class Demo02Servlet implements Servlet {
    /**
     * 初始化方法
     * 在Servlet被创建时执行。只会执行一次
     * @param servletConfig
     * @throws ServletException
     */
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        System.out.println("init...");
    }

    /**
     * 获取Servlet对象
     * @return
     */
    @Override
    public ServletConfig getServletConfig() {
        return null;
    }

    /**
     * 提供服务的方法
     * 每一次Servlet被访问，都会被执行。执行多次
     * @param servletRequest
     * @param servletResponse
     * @throws ServletException
     * @throws IOException
     */
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("service...");
    }

    /**
     * 获取Servlet的一些信息，版本、作者等等
     * @return
     */
    @Override
    public String getServletInfo() {
        return null;
    }

    /**
     * 销毁方法
     * 在服务器正常关闭时，执行一次
     */
    @Override
    public void destroy() {
        System.out.println("destory...");
    }
}

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<!--配置Servlet-->
    <servlet>
        <servlet-name>demo02</servlet-name>
        <servlet-class>demo01_servlet.Demo02Servlet</servlet-class>
        <!--指定Servlet的创建时机
        1. 第一次被访问时，创建。<load-on-startup>为负数，一般为-1
        2. 在服务器启动时，创建。<load-on-startup>为0或正整数，一般为0-10
        -->
        <load-on-startup>1</load-on-startup>
    </servlet>

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POST http://meethigher.top/admin/login.php HTTP/1.1
Host: meethigehr.top
Connection: keep-alive
Content-Length: 35
Cache-Control: max-age=0
Origin: http://baixiu-dev.top
Upgrade-Insecure-Requests: 1
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.79 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Referer: http://meethigher.top/
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9
Cookie: PHPSESSID=cdtnkpj4apnarjhtqugqegsfmn

email=admin@qq.com&password=admin

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HTTP/1.1 302 Found
Date: Tue, 09 Jun 2020 01:43:26 GMT
Server: Apache/2.4.34 (Win64) PHP/7.2.10
X-Powered-By: PHP/7.2.10
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate
Pragma: no-cache
Location: /admin/index.php
Content-Length: 2508
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/html; charset=UTF-8

<html>返回一套html代码，此处省略</html>

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@WebServlet("/demo01request")
public class Demo01Request extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        /*
         * 获取请求方式：String getMethod()
         * ❤获取虚拟目录：String getContextPath()
         * 获取Servlet路径：String getServletPath()
         * 获取get请求参数：String getQueryString()
         * ❤获取请求URI：String getRequestURI()和String getRequestURL()
         * 获取协议以及版本：String getProtocol()
         * 获取客户机ip地址：String getRemoteAddr()
         */
        System.out.println(request.getMethod());// GET
        System.out.println(request.getContextPath());// /demo
        System.out.println(request.getServletPath());// /demo01request
        System.out.println(request.getQueryString());// user=hh&password=123
        System.out.println(request.getRequestURI()+"---"+request.getRequestURL());// /demo/demo01request---http://localhost:8080/demo/demo01request
        System.out.println(request.getProtocol());// HTTP/1.1
        System.out.println(request.getRemoteAddr());// 这是获取的ipv6地址 0:0:0:0:0:0:0:1
    }
}

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@WebServlet("/demo02request")
public class Demo02Request extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Enumeration<String> headerNames = request.getHeaderNames();
        while (headerNames.hasMoreElements()) {
            String str = headerNames.nextElement();
            if ("user-agent".equals(str)) {
                String agent = request.getHeader(str);
                if (agent.contains("Chrome")) {
                    System.out.println("Chrome");
                } else if (agent.contains("Firefox")) {
                    System.out.println("Firefox");
                }

            }
        }

    }
}

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@WebServlet("/demo03request")
public class Demo03Request extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取请求消息体 请求参数
        request.setCharacterEncoding("utf-8");
        //1.获取字符流
        BufferedReader br=request.getReader();
        //2.读取数据
        String line=null;
        while((line=br.readLine())!=null){
            System.out.println(line);
        }
    }
}

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@WebServlet("/demo04request")
public class Demo04Request extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        //post获取请求参数
        //根据参数名称获取参数值
//        String user = request.getParameter("user");
//        String password = request.getParameter("password");
//        System.out.println(user+"--"+password);
//        //根据参数名称获取参数值数组
//        String[] hobbies=request.getParameterValues("beauty");
//        for (String hobby: hobbies) {
//            System.out.println(hobby);
//        }
        //获取所有请求的参数名称
//        Enumeration<String> parameterNames = request.getParameterNames();
//        while(parameterNames.hasMoreElements()){
//            System.out.println(parameterNames.nextElement());
//        }
        //测试热部署
        System.out.println("奥利给");//没卵用，百度一下，发现要用debug模式运行才可以

        //获取所有参数的Map集合
        Map<String, String[]> parameterMap = request.getParameterMap();
        //遍历
        Set<String> strings = parameterMap.keySet();
        for(String key:strings){
            System.out.println(key+"↓↓↓↓↓↓");
            //根据key获取值
            String[] strings1 = parameterMap.get(key);
            //遍历值数组
            for (String value:strings1) {
                System.out.println(value);
            }
            System.out.println("------");
        }

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

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@WebServlet("/demo05request")
public class Demo05Request extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("demo05request");
        request.setAttribute("女神","胡列娜");
        RequestDispatcher requestDispatcher = request.getRequestDispatcher("/demo06request");
        requestDispatcher.forward(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

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@WebServlet("/demo06request")
public class Demo06Request extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("demo06request");
        System.out.println(request.getAttribute("女神"));
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

1

request.setCharacterEncoding("utf-8")

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>登录</title>
</head>
<body>
<form action="loginServlet" method="post">
    名：<input type="text" name="user"><br>
    密：<input type="password" name="password"><br>
    <input type="submit" value="提交">
</form>
</body>
</html>

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/**
 * 操作数据中user表的类
 * @author https://github.com/meethigher
 */
public class UserDao {
    private JdbcTemplate temp=new JdbcTemplate(JDBCUtils.getDs());
    /**
     * 登录方法
     * @param loginUser 只有用户名和密码
     * @return 包含用户全部方法
     */
    public User login(User loginUser){
        try {
            //1.编写sql,只查询一条数据，因为我数据库里存储的内容有重复值，所有...
            String sql="select * from user where user=? and password=? limit 0,1";
            //2.调用template的查询方法
            User user = temp.queryForObject(sql,
                    new BeanPropertyRowMapper<User>(User.class),
                    loginUser.getUser(),loginUser.getPassword());
            return user;
        } catch (DataAccessException e) {
            //如果没有查到内容，返回null
            e.printStackTrace();//后期不再会使用打印异常，而是通过记录日志的方式
            return null;
        }
    }
}

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/**
 * 用户的JavaBean
 * @author https://github.com/meethigher
 */
public class User {
    private int id;
    private String user;
    private String password;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUser() {
        return user;
    }

    public void setUser(String user) {
        this.user = user;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

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/**
 * JDBC工具类，使用Druid连接池
 *
 * @author https://github.com/meethigher
 */
public class JDBCUtils {
    private static DataSource ds;

    /**
     * 静态代码块初始化连接池对象
     */
    static {
        try {
            //1.加载配置文件
            Properties pro = new Properties();
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);
            //2.初始化连接池对象
            ds = DruidDataSourceFactory.createDataSource(pro);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }


    }

    /**
     * 获取连接池对象
     * @return
     */
    public static DataSource getDs() {
        return ds;
    }

    /**
     * 获取连接对象
     * @return
     * @throws SQLException
     */
    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }
}

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/**
 * @author https://github.com/meethigher
 */
public class UserDaoTest {
    @Test
    public void testLogin(){
        User u=new User();
        u.setUser("胡列娜");
        u.setPassword("123f");
        UserDao udao=new UserDao();
        udao.login(u);
    }
}

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@WebServlet("/example/loginServlet")
public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置编码
        request.setCharacterEncoding("utf-8");
        //获取请求参数
        String user = request.getParameter("user");
        String password = request.getParameter("password");
        //封装User对象
        User loginUser = new User();
        loginUser.setUser(user);
        loginUser.setPassword(password);
        //调用UserDao的登录方法
        User login = new UserDao().login(loginUser);
        //判断是否登录成功
        if(login!=null){
            request.setAttribute("user",login);
            request.getRequestDispatcher("/example/successServlet").forward(request,response);
        }else{
            request.getRequestDispatcher("/example/failServlet").forward(request,response);
        }

    }
}

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//SuccessServlet.java
@WebServlet("/example/successServlet")
public class SuccessServle extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        User user = (User) request.getAttribute("user");
        response.getWriter().write(user.getUser()+"登录成功");
    }
}
//----------------------------------------------

//FailServlet.java
@WebServlet("/example/failServlet")
public class FailServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        response.getWriter().write("登录失败");
    }
}

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public class BeanUtilsTest {
    @Test
    public void test() throws InvocationTargetException, IllegalAccessException, NoSuchMethodException {
        User user = new User();
        BeanUtils.setProperty(user,"user","胡列娜");
        String user1 = BeanUtils.getProperty(user, "user");
        System.out.println(user+"--"+user1);// User{id=0, user='胡列娜', password='null'}--胡列娜
    }
}

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@WebServlet("/example/loginServlet")
public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置编码
        request.setCharacterEncoding("utf-8");
//        //获取请求参数
//        String user = request.getParameter("user");
//        String password = request.getParameter("password");
//        //封装User对象
//        User loginUser = new User();
//        loginUser.setUser(user);
//        loginUser.setPassword(password);

        //改用BeanUtils优化
        //获取所有请求参数
        Map<String, String[]> parameterMap = request.getParameterMap();
        //创建对象
        User loginUser = new User();
        //使用BeanUtils封装
        try {
            BeanUtils.populate(loginUser,parameterMap);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
        //调用UserDao的登录方法
        User login = new UserDao().login(loginUser);
        //判断是否登录成功
        if(login!=null){
            request.setAttribute("user",login);
            request.getRequestDispatcher("/example/successServlet").forward(request,response);
        }else{
            request.getRequestDispatcher("/example/failServlet").forward(request,response);
        }

    }
}

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@WebServlet("/demo01Response")
public class Demo01Response extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("demo01Response...");
        //访问 /demo01Response会自动跳转/demo02Response
//        //1.设置状态码为302
//        response.setStatus(302);
//        //2.设置响应头location
//        response.setHeader("location","/demo02Response");

        //因为重定向的步骤是一样的，所以java提供了简化版
        System.out.println(response.getClass().getName());
        response.sendRedirect("/demo02Response");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

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@WebServlet("/demo03Response")
public class Demo03Response extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //response获取的流，不需要刷新和关闭。因为response在一次响应结束之后，自动销毁
        //获取流对象之前，设置流的默认编码，但是如果客户端的机器有的是u8，有的是国标，还是会乱码
//        response.setCharacterEncoding("utf-8");
        //设置消息体数据的编码，建议浏览器使用该编码。不区分大写
//        response.setHeader("content-type","text/html;charset=utf-8");
        //当然，javaEE也给提供了更简便的方法
        response.setContentType("text/html;charset=utf-8");

        //1.获取字符输出流
        PrintWriter pw = response.getWriter();
        //2.输出数据
        pw.write("Hello Response");
        pw.write("胡列娜 我女神");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

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@WebServlet("/demo04Response")
public class Demo04Response extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=utf-8");
        //1.获取字节输出流
        ServletOutputStream os = response.getOutputStream();
        //2.输出数据
        os.write("胡列娜 我女神".getBytes("utf-8"));
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

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@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int width=500;
        int height=300;
        //1.创建对象，在内存中画图（验证码图片对象）
        BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
        //2.美化图片
        //2.1填充背景色
        Graphics g=image.getGraphics();//绘图对象
        g.setColor(Color.PINK);
        g.fillRect(0,0,width,height);
        //2.2画边框
        g.setColor(Color.RED);
        g.drawRect(0,0,width-1,height-1);
        System.out.println("奥利给");
        //2.3写验证码
        String str="ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";
        Random r=new Random();
        for (int i = 0; i < 4; i++) {
            g.drawString(str.charAt(r.nextInt(str.length()))+"",width/5*(i+1),height/2);
        }
        //2.4 画干扰线
        g.setColor(Color.green);
        for (int i = 0; i < 10; i++) {
            int x1=r.nextInt(width);
            int y1=r.nextInt(height);
            int x2=r.nextInt(width);
            int y2=r.nextInt(height);
            g.drawLine(x1,y1,x2,y2);
        }
        //3.将图片输出到页面展示
        ImageIO.write(image,"jpg",response.getOutputStream());
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<img src="/checkCodeServlet">
<a href="javascript:void(0)">看不清换一张</a>
<script>
    let $img=document.querySelector("img");
    $img.onclick = function () {
        let url = "/checkCodeServlet";
        let date=new Date().getTime();
        this.setAttribute("src", url+"?"+date)
    };
    document.querySelector("a").onclick=()=>{
        let url = "/checkCodeServlet";
        let date=new Date().getTime();
        $img.setAttribute("src", url+"?"+date)
    }
</script>
</body>
</html>

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@WebServlet("/demo02ServletContext")
public class Demo02ServletContext extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext servletContext = getServletContext();
        //定义文件名称
        String name="a.jpg";
        //获取MIME类型
        String mimeType = servletContext.getMimeType(name);
        System.out.println(mimeType);//image/jpeg
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

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@WebServlet("/demo03ServletContext")
public class Demo03ServletContext extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext servletContext = getServletContext();
        //设置数据
        servletContext.setAttribute("fairy","胡列娜");

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

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@WebServlet("/demo04ServletContext")
public class Demo04ServletContext extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext servletContext = getServletContext();
        //获取数据
        Object fairy = servletContext.getAttribute("fairy");
        System.out.println(fairy.toString());//胡列娜
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

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@WebServlet("/demo05ServletContext")
public class Demo05ServletContext extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext servletContext = getServletContext();
        String realPath = servletContext.getRealPath("/example/login.html");//获取web下文件
        System.out.println(realPath);//E:\Develop\JavaDev\JavaEE\out\artifacts\JavaEE_war_exploded\example\login.html
        String realPath1 = servletContext.getRealPath("/WEB-INF/web.xml");//获取WEB-INF目录下文件
        System.out.println(realPath1);
        //如果是直接放在src根目录下的，需要去/WEB-INF/classes/下找
        String realPath2 = servletContext.getRealPath("/WEB-INF/classes/a.html");//获取src目录下文件
        System.out.println(realPath2);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

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@WebServlet("/downloadServlet")
public class DownloadServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        //1.获取请求参数，文件名称
        String filename = request.getParameter("filename");
        //2.使用字节输入流加载文件进内存
        //2.1找到文件服务器路径
        ServletContext sc = getServletContext();
        String realPath = sc.getRealPath("/壁纸5.jpg");
        //2.2用字节流关联
        FileInputStream fis = new FileInputStream(realPath);
        //3设置response响应头
        //3.1设置响应格式
        String mimeType = sc.getMimeType(filename);
//        response.setHeader("content-type",mimeType);
        response.setContentType(mimeType);
        //3.2设置响应头打开格式
        //解决中文文件名问题，垃圾ie，去他妈的吧，兼容不了
        filename= URLEncoder.encode(filename,"utf-8");
        response.setHeader("content-disposition","attachment;filename="+filename);
        //4.将输入流数据写出到输出流中
        ServletOutputStream sos = response.getOutputStream();
        byte[] bytes = new byte[1024 * 8];
        int len=0;
        while((len=fis.read(bytes))!=-1){
            sos.write(bytes,0,len);
        }
        //5.释放资源
        fis.close();

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}