HTTP:
1. 概念:Hyper Text Transfer Protocol 超文本传输协议
-
传输协议:定义了,客户端和服务器端通信时,发送数据的格式
-
特点:
- 基于TCP/IP的高级协议
- 默认端口号:80
- 基于请求/响应模型的:一次请求对应一次响应
- 无状态的:每次请求之间相互独立,不能交互数据
-
历史版本:
- 1.0:每一次请求响应都会建立新的连接
- 1.1:复用连接
2. 请求消息数据格式
2.1 请求行
- 请求方式 请求
url
请求协议/版本 GET /login.html HTTP/1.1
- 请求方式:
HTTP
协议有7中请求方式,常用的有2种GET
:- 请求参数在请求行中,在
url
后。 - 请求的
url
长度有限制的 - 不太安全
- 请求参数在请求行中,在
POST
:- 请求参数在请求体中
- 请求的
url
长度没有限制的 - 相对安全
2.2 请求头:客户端浏览器告诉服务器一些信息
请求头名称: 请求头值
常见的请求头:
-
User-Agent
:浏览器告诉服务器,我访问你使用的浏览器版本信息可以在服务器端获取该头的信息,解决浏览器的兼容性问题
-
Referer
:http://localhost/login.html
告诉服务器,我(当前请求)从哪里来?
作用:
- 防盗链:
- 统计工作:
2.3 请求空行
- 空行,就是用于分割
POST
请求的请求头,和请求体的。
2.4 请求体(正文):
-
封装
POST
请求消息的请求参数的 -
字符串格式:
POST /login.html HTTP/1.1
Host: localhost
User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:60.0) Gecko/20100101 Firefox/60.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2
Accept-Encoding: gzip, deflate
Referer: http://localhost/login.html
Connection: keep-alive
Upgrade-Insecure-Requests: 1
username=zhangsan
3. 响应消息数据格式
3.1 Request:
3.1.1 request对象和response对象的原理
request
和response
对象是由服务器创建的。我们来使用它们request
对象是来获取请求消息,response
对象是来设置响应消息
3.1.2 request对象继承体系结构:
ServletRequest | 接口 |
继承 | |
HttpServletRequest | 接口 |
实现 |
org.apache.catalina.connector.RequestFacade@5b3cad0e
org.apache.catalina.connector.RequestFacade 类(tomcat)
3.1.3 request功能:
3.1.3.1 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:
-
获取请求方式 :
GET
String getMethod()
-
(*)
获取虚拟目录:/day14
String getContextPath()
-
获取
Servlet
路径:/demo1
String getServletPath()
-
获取
get
方式请求参数:name=zhangsan
String getQueryString()
-
(*)
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
(范围小)
URI
:统一资源标识符 :/day14/demo1 共和国
(范围大) -
获取协议及版本:
HTTP/1.1
String getProtocol()
-
获取客户机的IP地址:
String getRemoteAddr()
-
package com.example.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;
/**
* 演示Request对象获取请求行数据
*/
@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 getMethod()
2. (*)获取虚拟目录:/day14
* String getContextPath()
3. 获取Servlet路径: /requestDemo1
* 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/requestDemo1
* StringBuffer getRequestURL() :http://localhost/day14/requestDemo1
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()
*/
//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);
}
}
/*
GET
/day14
/requestDemo1
name=zhangsan
/day14/requestDemo1
http://localhost:8080/day14/requestDemo1
HTTP/1.1
0:0:0:0:0:0:0:1
*/
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
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);
}
}
}
package com.example.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...");
}
}
}
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);//http://localhost/day14/login.html
//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...");
}
}
}
}
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:
-
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 -
再从流对象中拿数据
-
3.1.3.2 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
String getParameter(String name)
:根据参数名称获取参数值username=zs&password=123
String[] getParameterValues(String name)
:根据参数名称获取参数值的数组hobby=xx&hobby=game
Enumeration<String> getParameterNames()
:获取所有请求的参数名称Map<String,String[]> getParameterMap()
:获取所有参数的map
集合
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");
//根据参数名称获取参数值的数组
String[] hobbies = request.getParameterValues("hobby");
/*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 {
this.doPost(request,response);
}
}
- 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");
- 解决:在获取参数前,设置
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("/requestDemo7")
public class RequestDemo7 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1.设置流的编码
request.setCharacterEncoding("utf-8");
//获取请求参数username
String username = request.getParameter("username");
System.out.println(username);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
2. 请求转发:一种在服务器内部的资源跳转方式
-
步骤:
- 通过
request
对象获取请求转发器对象:RequestDispatcher getRequestDispatcher(String path)
- 使用
RequestDispatcher
对象来进行转发
forward(ServletRequest request, ServletResponse response)
- 通过
-
特点:
- 浏览器地址栏路径不发生变化
- 只能转发到当前服务器内部资源中。
- 转发是一次请求
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("https://www.baidu.com").forward(request,response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,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("/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:
void setAttribute(String name,Object obj)
:存储数据Object getAttitude(String name)
:通过键获取值void removeAttribute(String name)
:通过键移除键值对
4. 获取ServletContext:
ServletContext getServletContext()
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);
}
}
案例:用户登录
-
用户登录案例需求:
- 编写
login.html
登录页面
username & password
两个输入框 - 使用
Druid
数据库连接池技术,操作mysql,day14
数据库中user
表 - 使用
JdbcTemplate
技术封装JDBC
- 登录成功跳转到
SuccessServlet
展示:登录成功!用户名,欢迎您 - 登录失败跳转到
FailServlet
展示:登录失败,用户名或密码错误
- 编写
-
分析
-
开发步骤
- 创建项目,导入html页面,配置文件,jar包
- 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
);
- 创建包cn.example.domain,创建类User
/**
* 用户的实体类
*/
public class User {
private int id;
private String username;
private String password;
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 + '\'' +
'}';
}
}
- 创建包cn.example.util,编写工具类JDBCUtils
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();
}
}
- 创建包cn.example.dao,创建类UserDao,提供login方法
import cn.example.domain.User;
import cn.example.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;
}
}
}
- 编写cn.example.web.servlet.LoginServlet类
import cn.example.dao.UserDao;
import cn.example.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("/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);
//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);
}
}
- 编写FailServlet和SuccessServlet类
@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");
}
}
@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);
}
}
-
login.html
中form
表单的action
路径的写法虚拟目录+Servlet的资源路径
-
BeanUtils
工具类,简化数据封装- 用于封装
JavaBean
的
-
JavaBean
:标准的Java
类- 要求:
- 类必须被
public
修饰 - 必须提供空参的构造器
- 成员变量必须使用
private
修饰 - 提供公共
setter
和getter
方法
- 类必须被
- 功能:封装数据
- 要求:
-
概念:
成员变量:
属性:setter
和getter
方法截取后的产物
例如:getUsername() --> Username--> username
-
方法:
setProperty()
getProperty()
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
- 用于封装
package com.example.web.servlet;
import com.example.damain.User;
import com.example.dao.UserDao;
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 doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
//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();
}
UserDao dao = new UserDao();
User user = dao.login(loginUser);
if(user == null){
req.getRequestDispatcher("/failServlet").forward(req,resp);
}else{
req.setAttribute("user",user);
req.getRequestDispatcher("/successServlet").forward(req,resp);
}
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
super.doPost(req, resp);
}
}
public class BeanUtilsTest {
@Test
public void test(){
User user = new User();
try {
BeanUtils.setProperty(user,"hehe","male");
System.out.println(user);
String gender = BeanUtils.getProperty(user, "hehe");
System.out.println(gender);
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
} catch (NoSuchMethodException e) {
e.printStackTrace();
}
}
}