08Request

1.request对象和response对象的原理

1. request和response对象是由服务器创建的。我们来使用它们
 2. request对象是来获取请求消息，response对象是来设置响应消息

2. request对象继承体系结构

ServletRequest        --    接口
            |    继承
        HttpServletRequest    -- 接口
            |    实现
        org.apache.catalina.connector.RequestFacade 类(tomcat)

3. request功能

3.1 获取请求消息数据

1. 获取请求行数据
　　 GET /day14/demo1?name=zhangsan HTTP/1.1
　　 方法：
　　1. 获取请求方式 ：GET
　　        String getMethod()  
　　2. (*)获取虚拟目录：/day14
　　　　 String getContextPath()
　　3. 获取Servlet路径: /demo1
　　　　String getServletPath()
　　4. 获取get方式请求参数：name=zhangsan
　　　　String getQueryString()
　　5. (*)获取请求URI：/day14/demo1
　　　　String getRequestURI():        /day14/demo1
　　　　StringBuffer getRequestURL()  :http://localhost/day14/demo1

　　　　　　URL:统一资源定位符 ： http://localhost/day14/demo1    中华人民共和国
　　　　　　URI：统一资源标识符 : /day14/demo1                    共和国（范围更大）
                
　　6. 获取协议及版本：HTTP/1.1
　　　　 String getProtocol()

　　7. 获取客户机的IP地址：
　　　　String getRemoteAddr()

package cn.itcast.web.request;

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("/RequestDemo1")
public class RequestDemo1 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1. 获取请求方式 ：GET
        String method = request.getMethod();
        System.out.println(method);
        //2.(*)获取虚拟目录：/day14
        String contextPath = request.getContextPath();
        System.out.println(contextPath);
        //3. 获取Servlet路径: /demo1
        String servletPath = request.getServletPath();
        System.out.println(servletPath);
        //4. 获取get方式请求参数：name=zhangsan
        String queryString = request.getQueryString();
        System.out.println(queryString);
        //5.(*)获取请求URI：/day14/demo1
        String requestURI = request.getRequestURI();
        StringBuffer requestURL = request.getRequestURL();
        System.out.println(requestURI);
        System.out.println(requestURL);
        //6. 获取协议及版本：HTTP/1.1
        String protocol = request.getProtocol();
        System.out.println(protocol);
        //7. 获取客户机的IP地址：
        String remoteAddr = request.getRemoteAddr();
        System.out.println(remoteAddr);
    }
}

                
2. 获取请求头数据
　　方法：
　　　　 (*)String getHeader(String name):通过请求头的名称获取请求头的值
　　　　 Enumeration<String> getHeaderNames():获取所有的请求头名称

package cn.itcast.web.request;

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.Enumeration;

@WebServlet("/RequestDemo2")
public class RequestDemo2 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //演示获取请求头数据

        //1.获取所有请求头名称
        Enumeration<String> headerNames = request.getHeaderNames();
        //2.遍历
        while(headerNames.hasMoreElements()){
            String name = headerNames.nextElement();
            //根据名称获取请求头的值
            String value = request.getHeader(name);
            System.out.println(name+"---"+value);
        }

    }
}

3. 获取请求体数据:
　　请求体：只有POST请求方式，才有请求体，在请求体中封装了POST请求的请求参数
　　步骤：
　　1. 获取流对象
　　BufferedReader getReader()：获取字符输入流，只能操作字符数据
　　ServletInputStream getInputStream()：获取字节输入流，可以操作所有类型数据
　　在文件上传知识点后讲解
　　 2. 再从流对象中拿数据

package cn.itcast.web.request;

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.Enumeration;

@WebServlet("/RequestDemo3")
public class RequestDemo3 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //演示获取请求头数据:user-agent

        String agent = request.getHeader("user-agent");
        //判断agent的浏览器版本
        if(agent.contains("Chrome")){
            //谷歌
            System.out.println("谷歌来了...");
        }else if(agent.contains("Firefox")){
            //火狐
            System.out.println("火狐来了...");
        }

    }
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <form action="/demo3" method="POST">
        <input name="username">
        <input type="submit" value="提交">

    </form>
<hr>

<a href="/day13Servlet/RequestDemo4">demo4...</a>

</body>
</html>

package cn.itcast.web.request;

import javax.servlet.ServletContext;
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("/RequestDemo4")
public class RequestDemo4 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //演示获取请求头数据:referer

        String referer = request.getHeader("referer");
        System.out.println(referer);

        //防盗链
        if(referer != null ){
            if(referer.contains("/day14")){
                //正常访问
               // System.out.println("播放电影....");
                response.setContentType("text/html;charset=utf-8");
                response.getWriter().write("播放电影....");
            }else{
                //盗链
                //System.out.println("想看电影吗？来优酷吧...");
                response.setContentType("text/html;charset=utf-8");
                response.getWriter().write("想看电影吗？来优酷吧...");
            }
        }

    }
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>注册页面</title>
</head>
<body>

    <form action="/day13Servlet/RequestDemo5" method="post">
        <input type="text" placeholder="请输入用户名" name="username"><br>
        <input type="text" placeholder="请输入密码" name="password"><br>
        <input type="submit" value="注册">

    </form>

</body>
</html>

package cn.itcast.web.request;

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("/RequestDemo5")
public class RequestDemo5 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取请求消息体--请求参数

        //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);
        }

    }

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

3.2 其他功能

1. 获取请求参数通用方式：不论get还是post请求方式都可以使用下列方法来获取请求参数
　　1. String getParameter(String name):根据参数名称获取参数值    username=zs&password=123
　　2. String[] getParameterValues(String name):根据参数名称获取参数值的数组  hobby=xx&hobby=game
　　3. Enumeration<String> getParameterNames():获取所有请求的参数名称
　　4. Map<String,String[]> getParameterMap():获取所有参数的map集合

　　中文乱码问题：
　　　　 get方式：tomcat 8 已经将get方式乱码问题解决了
　　　　 post方式：会乱码
　　　　解决：在获取参数前，设置request的编码request.setCharacterEncoding("utf-8");

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>注册页面</title>
</head>
<body>

    <form action="/day13Servlet/RequestDemo6" method="post">
        <input type="text" placeholder="请输入用户名" name="username"><br>
        <input type="text" placeholder="请输入密码" name="password"><br>
        <input type="submit" value="注册">

    </form>

</body>
</html>

package cn.itcast.web.request;

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;
import java.util.Enumeration;
import java.util.Map;
import java.util.Set;

@WebServlet("/RequestDemo6")
public class RequestDemo6 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //post 获取请求参数

        //根据参数名称获取参数值
        String username = request.getParameter("username");
       /* System.out.println("post");
        System.out.println(username);*/

       //根据参数名称获取参数值的数组
        String[] hobbies = request.getParameterValues("hobby"); //主要是复选框用
        /*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()){
            String name = parameterNames.nextElement();
            System.out.println(name);
            String value = request.getParameter(name);
            System.out.println(value);
            System.out.println("----------------");
        }*/

        // 获取所有参数的map集合
        Map<String, String[]> parameterMap = request.getParameterMap();
        //遍历
        Set<String> keyset = parameterMap.keySet();
        for (String name : keyset) {

            //获取键获取值
            String[] values = parameterMap.get(name);
            System.out.println(name);
            for (String value : values) {
                System.out.println(value);
            }

            System.out.println("-----------------");
        }

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //get 获取请求参数
/*
        //根据参数名称获取参数值
        String username = request.getParameter("username");
        System.out.println("get");
        System.out.println(username);*/

        this.doPost(request,response);
    }
}

2. 请求转发：一种在服务器内部的资源跳转方式
　　1. 步骤：
　　　　1. 通过request对象获取请求转发器对象：RequestDispatcher getRequestDispatcher(String path)
　　　　2. 使用RequestDispatcher对象来进行转发：forward(ServletRequest request, ServletResponse response)

　　2. 特点：
　　　　1. 浏览器地址栏路径不发生变化
　　　　2. 只能转发到当前服务器内部资源中。
　　　　3. 转发是一次请求

package cn.itcast.web.request;

import javax.servlet.RequestDispatcher;
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("/RequestDemo8")
public class RequestDemo8 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("demo8888被访问了。。。");
        //转发到demo9资源
/*
        RequestDispatcher requestDispatcher = request.getRequestDispatcher("/requestDemo9");
        requestDispatcher.forward(request,response);
        */

        //存储数据到request域中
        request.setAttribute("msg","hello");

        request.getRequestDispatcher("/RequestDemo9").forward(request,response);
        //request.getRequestDispatcher("http://www.itcast.cn").forward(request,response);

    }

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

        this.doPost(request,response);
    }
}

package cn.itcast.web.request;

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("/RequestDemo9")
public class RequestDemo9 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //获取数据
        Object msg = request.getAttribute("msg");
        System.out.println(msg);

        System.out.println("demo9999被访问了。。。");

    }

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

        this.doPost(request,response);
    }
}

3. 共享数据：
　　　　域对象：一个有作用范围的对象，可以在范围内共享数据
　　　　request域：代表一次请求的范围，一般用于请求转发的多个资源中共享数据
　　　　方法：
　　　　1. void setAttribute(String name,Object obj):存储数据
　　　　2. Object getAttitude(String name):通过键获取值
　　　　3. void removeAttribute(String name):通过键移除键值对

4. 获取ServletContext：
　　　　ServletContext getServletContext()

package cn.itcast.web.request;

import javax.servlet.ServletContext;
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("/RequestDemo10")
public class RequestDemo10 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        ServletContext servletContext = request.getServletContext();

        System.out.println(servletContext);

    }

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

        this.doPost(request,response);
    }
}

4.登录案例

用户登录案例需求：

1.编写login.html登录页面
username & password 两个输入框
2.使用Druid数据库连接池技术,操作mysql，day14数据库中user表
3.使用JdbcTemplate技术封装JDBC
4.登录成功跳转到SuccessServlet展示：登录成功！用户名,欢迎您
5.登录失败跳转到FailServlet展示：登录失败，用户名或密码错误

4.1开发步骤

1. 创建项目，导入html页面，配置文件，jar包

2. 创建数据库环境

CREATE DATABASE day14;

USE day14;

CREATE TABLE USER(
    id INT PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(32) UNIQUE NOT NULL,
    PASSWORD VARCHAR(32) NOT NULL
);

3. 创建包cn.itcast.domain,创建类User

package cn.itcast.domain;

/**
 * 用户的实体类
 */
public class User {

    private int id;
    private String username;
    private String password;

    private String gender;

    public void setHehe(String gender) {
        this.gender = gender;
    }

    public String getHehe() {
        return gender;
    }

    public int getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

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

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", gender='" + gender + '\'' +
                '}';
    }
}

4.创建包cn.itcast.util,编写工具类JDBCUtils

package cn.itcast.util;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import javax.xml.crypto.Data;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;

/**
 * JDBC工具类 使用Durid连接池
 */
public class JDBCUtils {

    private static DataSource ds;

    static {

        try {
            //1.加载配置文件
            Properties pro = new Properties();
            //使用ClassLoader加载配置文件，获取字节输入流
            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
     */
    public static DataSource getDataSource() {
        return ds;
    }

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

5. 创建包cn.itcast.dao,创建类UserDao,提供login方法

package cn.itcast.dao;

import cn.itcast.domain.User;
import cn.itcast.util.JDBCUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

/**
 * 操作数据库中User表的类
 */
public class UserDao {

    //声明JDBCTemplate对象共用
    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());

    /**
     * 登录方法
     * @param loginUser 只有用户名和密码
     * @return user包含用户全部数据,没有查询到，返回null
     */
    public User login(User loginUser){
        try {
            //1.编写sql
            String sql = "select * from user where username = ? and password = ?";
            //2.调用query方法
            User user = template.queryForObject(sql,
                    new BeanPropertyRowMapper<User>(User.class),
                    loginUser.getUsername(), loginUser.getPassword());

            return user;
        } catch (DataAccessException e) {
            e.printStackTrace();//记录日志
            return null;
        }
    }
}

6. 编写cn.itcast.web.servlet.LoginServlet类

package cn.itcast.web.servlet;

import cn.itcast.dao.UserDao;
import cn.itcast.domain.User;
import org.apache.commons.beanutils.BeanUtils;

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.lang.reflect.InvocationTargetException;
import java.util.Map;

@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.设置编码
        req.setCharacterEncoding("utf-8");
       /* //2.获取请求参数
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        //3.封装user对象
        User loginUser = new User();
        loginUser.setUsername(username);
        loginUser.setPassword(password);*/
        //2.获取所有请求参数
        Map<String, String[]> map = req.getParameterMap();
        //3.创建User对象
        User loginUser = new User();
        //3.2使用BeanUtils封装
        try {
            BeanUtils.populate(loginUser,map);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }

        //4.调用UserDao的login方法
        UserDao dao = new UserDao();
        User user = dao.login(loginUser);

        //5.判断user
        if(user == null){
            //登录失败
            req.getRequestDispatcher("/FailServlet").forward(req,resp);
        }else{
            //登录成功
            //存储数据
            req.setAttribute("user",user);
            //转发
            req.getRequestDispatcher("/SuccessServlet").forward(req,resp);
        }

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req,resp);
    }
}

package cn.itcast.web.servlet;

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("/FailServlet")
public class FailServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //给页面写一句话

        //设置编码
        response.setContentType("text/html;charset=utf-8");
        //输出
        response.getWriter().write("登录失败，用户名或密码错误");

    }

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

package cn.itcast.web.servlet;

import cn.itcast.domain.User;

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("/SuccessServlet")
public class SuccessServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取request域中共享的user对象
        User user = (User) request.getAttribute("user");

        if(user != null){
            //给页面写一句话

            //设置编码
            response.setContentType("text/html;charset=utf-8");
            //输出
            response.getWriter().write("登录成功！"+user.getUsername()+",欢迎您");
        }

    }

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

 注意：跳转的路径应该和tomcat中配置一样，否则会找不到资源，404错误。

8. login.html中form表单的action路径的写法
　　虚拟目录+Servlet的资源路径

9. BeanUtils工具类，简化数据封装
　　用于封装JavaBean的
　　1. JavaBean：标准的Java类
　　　　1. 要求：
                    1. 类必须被public修饰
                    2. 必须提供空参的构造器
                    3. 成员变量必须使用private修饰
                    4. 提供公共setter和getter方法
                2. 功能：封装数据

　　2. 概念：
                成员变量：
                属性：setter和getter方法截取后的产物
                    例如：getUsername() --> Username--> username

　　3. 方法：
                1. setProperty()
                2. getProperty()
                3. populate(Object obj , Map map):将map集合的键值对信息，封装到对应的JavaBean对象中