* 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: 1.基于TCP/IP的高级协议 2.默认端口号:80 3.基于请求/响应模型的:一次请求对应一次响应 4.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
* 请求消息数据格式 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: 1. 请求参数在请求行中,在url后。 2. 请求的url长度有限制的 3. 不太安全 * POST: 1. 请求参数在请求体中 2. 请求的url长度没有限制的 3. 相对安全 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: 1. 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 2. Referer:http://localhost/login.html * 告诉服务器,我(当前请求)从哪里来? * 作用: 1. 防盗链: 2. 统计工作: 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。 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
* 数据格式: 1. 1. 组成:协议/版本 响应状态码 状态码描述 2. 响应状态码:服务器告诉客户端浏览器本次请求和响应的一个状态。 1. 状态码都是3位数字 2. 分类: 1. 1xx:服务器就收客户端消息,但没有接受完成,等待一段时间后,发送1xx多状态码 2. 2xx:成功。代表:200 3. 3xx:重定向。代表:302(重定向),304(访问缓存) 4. 4xx:客户端错误。 * 代表: * 404(请求路径没有对应的资源) * 405:请求方式没有对应的doXxx方法 5. 5xx:服务器端错误。代表:500(服务器内部出现异常)
1. 格式:头名称: 值 2. 常见的响应头: 1. Content-Type:服务器告诉客户端本次响应体数据格式以及编码格式 2. Content-disposition:服务器告诉客户端以什么格式打开响应体数据 * 值: * in-line:默认值,在当前页面内打开 * attachment;filename=xxx:以附件形式打开响应体。文件下载
传输的数据
* 响应字符串格式
HTTP/1.1 200 OK
Content-Type: text/html;charset=UTF-8
Content-Length: 101
Date: Wed, 06 Jun 2018 07:08:42 GMT
<html>
<head>
<title>$Title$</title>
</head>
<body>
hello , response
</body>
</html>
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对象是来设置响应对象
ServletRequest -- 接口 | 继承 HttpServletRequest -- 接口 | 实现 org.apache.catalina.connector.RequestFacade 类(由tomcat编写的)
* GET /day11/demo1?name=zhangsan HTTP/1.1
* 方法:
1.获取请求方式:GET
* String getMethod()
2.(重点)获取虚拟目录:/day11
* 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.(重点)获取请求URI:/day11/demo1
* String getRequestURI(): /day11/demo1
* StringBuffer getRequestURL(): http://localhost/day11/demo1
*URL:统一资源定位符:http://localhost/day11/demo1 中华人民共和国
*URI:统一资源标识符:/day11/demo1 共和国
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 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.(重点)获取虚拟目录:/day11
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.(重点)获取请求URI:/day11/demo1
// * String getRequestURI(): /day11/demo1
// * StringBuffer getRequestURL(): http://localhost/day11/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);
}
}
* 方法:
* (重点)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
* 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
-----------------------------------------------------------
* 代码示例:
--------------------------------------
* 文件名:regist.html *
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>regist</title>
</head>
<body>
<form action="/RequestDemo2" method="post">
<input type="text" name="username" placeholder="请输入用户名">
<input type="text" name="password" placeholder="请输入密码" >
<input type="submit" value="提交">
</form>
</body>
</html>
--------------------------------------
* 文件名:RequestDemo2.java *
package 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("/RequestDemo2")
public class RequestDemo2 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取请求体---请求参数
//1.获取字符流
BufferedReader reader = request.getReader();
//2.读取数据
String line = null;
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
}
--------------------------------------
2.再从流对象中拿数据
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=study&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
package 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;
import java.util.Map;
import java.util.Set;
@WebServlet("/RequestDemo3")
public class RequestDemo3 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1.String getParameter(String name):根据参数名称获取参数值
String username = request.getParameter("username");
// System.out.println(username);
//2.String[] getParameterValues(String name):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);
}*/
//3.Enumeration<String> getParameterNames():获取所有请求的参数名称
Enumeration<String> parameterNames = request.getParameterNames();
/* while (parameterNames.hasMoreElements()){
String nextElement = parameterNames.nextElement();
System.out.println(nextElement);
String parameter = request.getParameter(nextElement);
System.out.println(parameter);
System.out.println("==========");
}*/
//4.Map<String,String[]> getParameterMap():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) {
//获取键值对
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 {
//相同调用方法调用时,可以用这种形式调用
this.doPost(request,response);
}
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>regist2</title>
</head>
<body>
<form action="/RequestDemo3" method="post">
<input type="text" name="username" placeholder="请输入用户名"><br>
<input type="text" name="password" placeholder="请输入密码"><br>
<input type="checkbox" name="hobby" value="study">学习
<input type="checkbox" name="hobby" value="game">游戏
<br>
<input type="submit" value="提交">
</form>
</body>
</html>
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)
* 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
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 {
//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);
}
}
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("/requestDemo6")
public class RequestDemo6 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");
//转发资源
request.getRequestDispatcher("/requestDemo7").forward(request,response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
* ServletContext getServletContext()
** 此次课程略讲,下节课详讲
----------------------------------------------------------
@WebServlet("/requestDemo8")
public class RequestDemo8 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);
}
}
* 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");
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //解决中文乱码 request.setCharacterEncoding("utf-8"); //根据参数名称获取参数值 String username = request.getParameter("username"); System.out.println(username); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { }
}
### 6. BeanUtils工具类,简化数据封装
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
# Response: ## 1. 功能:
* 字符输出流:PrintWriter getWriter() * 字节输出流:ServletOutputStream getOutputStream()
2.使用输出流,将数据输出到客户端浏览器## 2. 重定向: ```java * 重定向:资源跳转的方式 * 代码实现: //方式1: //1.设置状态码:302 response.setStatus(302); //2.设置响应头:location response.setHeader("location","/responseDemo2"); //方式2: //简单的重定位方法: response.sendRedirect("/responseDemo2");
* 重定向的特点:redirect 1.地址栏发生变化; 2.重定向可以访问其他站点(服务器)的资源; 3.重定向是两次请求。不能使用request对象来共享数据
* 转发的特点:forward 1.转发地址栏路径不见; 2.转发只能访问当前服务器下的资源; 3.转发是一次请求,可以使用request对象来共享数据
* 路径分类: 1.相对路径:通过 相对路径不可以确定唯一资源 * 如:./index.html * 不以斜杠(/)开头,以.开头路径 * 规则:找到当前资源和目标资源之间的相对位置关系 * ./:当前目录 * ../:后退一级目录
2.绝对路径:通过绝对路径可以确定唯一资源 * 如:http://localhost/day15/responseDemo2 /day15/responseDemo2 * 以/开头的路径 * 规则:判断定义的路径是给谁使用的?判断请求将来从哪儿发出 * 给客户端浏览器使用:需要加虚拟目录(项目的访问路径) * 建议虚拟目录动态获取:request.getContextPath() * <a>,<form> 重定向... *代码示例: //动态获取虚拟目录 String contextPath = request.getContextPath(); response.sendRedirect(contextPath+"/responseDemo2"); --------------------------------------------------------- *给服务器使用:不需要加虚拟目录 * 转发路径
* 步骤:
//1.获取字符输出流
PrintWriter pw = response.getWriter();
//2.输出数据
pw.write("<h1>hello response</h1>");
* 注意:
* 乱码问题:
因为:PrintWriter pw = response.getWriter();获取的流的默认编码是ISO-8859-1,因此需要我们设置该流的默认编码,告诉浏览器响应体使用的编码。
//设置编码,是在获取流之前设置
response.setContentType("text/html;charset=utf-8");
* 代码示例:
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;
@WebServlet("/responseDemo4")
public class ResponseDemo4 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//设置编码,是在获取流之前设置
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("<h1>你好 response</h1>");
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
* 步骤:
//设置编码
response.setContentType("text/html;charset=utf-8");
//1.获取字节输出流
ServletOutputStream sos= response.getOutputStream();
//2.输出数据
sos.write("你好".getBytes("utf-8"));
import javax.imageio.ImageIO;
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.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1.创建一个对象,在内存中图片(验证码图片对象)
int wight = 100;
int height = 50;
BufferedImage image = new BufferedImage(wight, height, BufferedImage.TYPE_INT_RGB);
// 2.美化图片
//2.1 填充背景色(默认黑色)
Graphics g = image.getGraphics();//添加画笔对象
g.setColor(Color.PINK);//设置画笔颜色
g.fillRect(0, 0, wight, height);//设置起始范围
//2.2画边框
g.setColor(Color.BLUE);
g.drawRect(0, 0, wight - 1, height - 1);//同上,因为边框本身有大小,因此需要-1,否则超出范围
//2.3 写验证码
String s = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
//生成随机脚标
Random r = new Random();
for (int i = 1; i <= 4; i++) {
int index = r.nextInt(s.length());
//获取字符
char c = s.charAt(index);//随机字符
g.drawString(c + "", wight / 5 * i, height / 2);
}
//2.4 画干扰线
g.setColor(Color.GREEN);
//随机生成坐标点
for (int i = 0; i < 10; i++) {
int x1 = r.nextInt(wight);
int x2 = r.nextInt(wight);
int y1 = r.nextInt(height);
int y2 = r.nextInt(height);
g.drawLine(x1,x2,y1,y2);
}
//3.将图片输出在页面上
ImageIO.write(image, "jpg", response.getOutputStream());
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script>
window.onclick = function () {
//1.获取图片对象
var img = document.getElementById("checkCode");
//2.绑定单击事件
img.onclick = function () {
//加时间戳
var date = new Date().getTime();
img.src = "/Response/checkCodeServlet?" + date;
}
}
</script>
</head>
<body>
<img id="checkCode" src="/Response/checkCodeServlet" >
<a id="change" href="">看不起?换一张</a>
</body>
</html>
* 代表整个web应用,可以和程序的容器(服务器)来通信
//获取方式1:
//通过request对象获取:
//request.getServletContext();
ServletContext context1 = request.getServletContext();
//获取方式2:
//通过HTTPServlet获取
//this.getServletContext();
ServletContext context2 = this.getServletContext();
1.获取MIME类型:
* MIME类型:在互联网通信过程中定义的一种文件数据类型
* 格式: 大类型/小类型 text/html image/jpg
* 获取:String getMimeType(String file)
//1.通过HTTPServlet获取:
ServletContext context = this.getServletContext();
//2.定义文件名称:
String fileName = "a.jpg";
//3.获取MIME类型:
String mimeType = context.getMimeType(fileName);
System.out.println(mimeType);
1.setAttribute(String name,Object value)
2.getAttribute(String name)
3.removeAttributes(String name)
* ServletContext对象范围:所有用户所有请求的数据
* 因此要慎重使用
方法:String getRealPath(String path)
//获取ServletContext对象
ServletContext context = this.getServletContext();
//获取文件的服务器路径
String b = context.getRealPath("/b.txt");//web下的资源访问
System.out.println(b);
String c = context.getRealPath("/WEB-INF/c.txt");//WEB-INF目录下的资源访问
System.out.println(c);
String a = context.getRealPath("/WEB-INF/classes/a.txt");//src目录下的资源访问
System.out.println(a);
* 文件下载需求:
1. 页面显示超链接
2. 点击超链接后弹出下载提示框
3. 完成图片文件下载
* 分析:
1. 超链接指向的资源如果能够被浏览器解析,则在浏览器中展示,如果不能解析,则弹出下载提示框。不满足需求
2. 任何资源都必须弹出下载提示框
3. 使用响应头设置资源的打开方式:
* content-disposition:attachment;filename=xxx
* 步骤:
1. 定义页面,编辑超链接href属性,指向Servlet,传递资源名称filename
2. 定义Servlet
1. 获取文件名称
2. 使用字节输入流加载文件进内存
3. 指定response的响应头: content-disposition:attachment;filename=xxx
4. 将数据写出到response输出流
* 问题:
* 中文文件问题
* 解决思路:
1. 获取客户端使用的浏览器版本信息
2. 根据不同的版本信息,设置filename的编码方式不同
package ServletContext;
import utils.DownLoadUtils;
import javax.servlet.ServletContext;
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;
@WebServlet("/downloadServlet")
public class DownloadServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//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 servletContext = this.getServletContext();
String realPath = servletContext.getRealPath("/img/" + filename);
//2.2用字节流关联
FileInputStream fis = new FileInputStream(realPath);
//3.设置response的响应头
//3.1设置响应头类型:content-type
String mimeType = servletContext.getMimeType(filename);//获取文件的mime类型
response.setHeader("content-type", mimeType);
//3.2设置响应头打开方式:content-disposition
//解决中文文件名问题
//1.获取user-agent请求头、
String agent = request.getHeader("user-agent");
//2.使用工具类方法编码文件名即可
filename = DownLoadUtils.getFileName(agent, filename);
response.setHeader("content-disposition","attachment;filename"+filename);
//4.将输入流的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);
}
fis.close();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}