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
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