【Javaweb】----狂神筆記（僅作為學習記錄使用）
阿新 • • 發佈：2021-07-26
1. 基本概念
2. Web伺服器
3. Tomcat
# 4. Http
4.3. Http請求
4.4. Http響應
5. Maven
https://github.com/fanjianhai/kuangshen/tree/master/0.IDEA常用配置記錄
6. Servlet
6.3. Servlet原理
- 一個 Servlet可以指定多個對映路徑
<servlet> <servlet-name>hello</servlet-name> <servlet-class>com.xiaofan.servlet.HelloServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>hello</servlet-name> <url-pattern>/hello</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>hello</servlet-name> <url-pattern>/hello1</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>hello</servlet-name> <url-pattern>/hello2</url-pattern> </servlet-mapping>
- 一個Servlet可以指定通用對映路徑
<servlet-mapping>
<servlet-name>hello</servlet-name>
<url-pattern>/hello/*</url-pattern>
</servlet-mapping>
注意定義字尾，不用設定前面的路徑，預設會匹配上
-
優先順序問題
指定了固有的對映路徑優先順序最高，如果找不到就會走預設的處理
- 共享資料
- 獲取初始化引數
String url = this.getServletContext().getInitParameter("url");
<context-param>
<param-name>url</param-name>
<param-value>www.baidu.com</param-value>
</context-param>
- 請求轉發
this.getServletContext().getRequestDispatcher("/index").forward(req, resp);
- 讀取資原始檔Properties
<!--靜態資源匯出--> <build> <resources> <resource> <directory>src/main/java</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>false</filtering> </resource> <resource> <directory>src/main/resources</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>false</filtering> </resource> </resources> </build>
// 注意路徑的取法
InputStream inputStream = this.getServletContext().getResourceAsStream("/WEB-INF/classes/db.properties");
Properties properties = new Properties();
properties.load(inputStream);
String username = properties.getProperty("username");
String password = properties.getProperty("password");
System.out.println("username:" + username + "\npassword: " + password);
6.4. Response下載檔案
public class FileServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String realPath = "D:\\JavaWebLocalProject\\javaweb-01-servlet\\servlet-01\\target\\servlet-01-1.0-SNAPSHOT\\WEB-INF\\classes\\abc.jpg";
System.out.println(realPath);
String fileName = realPath.substring(realPath.lastIndexOf("\\") + 1);
resp.setHeader("Content-Disposition","attachment;filename="+ URLEncoder.encode(fileName, "UTF-8"));
FileInputStream in = new FileInputStream(realPath);
ServletOutputStream out = resp.getOutputStream();
int len = 0;
byte[] buffer = new byte[1024];
while ((len = in.read(buffer)) > 0) {
out.write(buffer, 0, len);
}
in.close();
out.close();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
6.5 驗證碼的生成
package com.xiaofan.servlet;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
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;
public class ImageServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setHeader("refresh", "3");
BufferedImage image = new BufferedImage(80, 20, BufferedImage.TYPE_INT_BGR);
Graphics2D g = (Graphics2D) image.getGraphics();
g.setColor(Color.white);
g.fillRect(0,0, 80, 20);
g.setColor(Color.BLUE);
g.setFont(new Font(null, Font.BOLD, 20));
g.drawString(makeNum(), 0, 20);
resp.setContentType("image/jpeg");
resp.setDateHeader("expires", -1);
resp.setHeader("Cache-Control", "no-cache");
resp.setHeader("Pragma", "no-cache");
ImageIO.write(image, "jpeg", resp.getOutputStream());
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
private String makeNum() {
Random random = new Random();
String num = random.nextInt(9999999) + "";
StringBuffer sb = new StringBuffer();
for (int i = 0;i < 7-num.length();i ++) {
sb.append("0");
}
num = sb.toString() + num;
return num;
}
}
6.6. 轉發重定向
7 Cookie和Session
package com.xiaofan.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;
public class CookieServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 解決中文亂碼
req.setCharacterEncoding("utf-8");
resp.setCharacterEncoding("utf-8");
resp.setContentType("text/html;charset=utf-8");
PrintWriter out = resp.getWriter();
// 伺服器從客戶端獲取cookie
Cookie[] cookies = req.getCookies();
if (cookies != null) {
out.write("您上一次的訪問時間是：");
for (int i = 0; i < cookies.length; i++) {
Cookie cookie = cookies[i];
if (cookie.getName().equals("lastLoginTime")) {
// 獲取cookie中的值
long lastLoginTime = Long.parseLong(cookie.getValue());
Date date = new Date(lastLoginTime);
out.write(date.toLocaleString());
}
}
} else {
out.write("這是您第一次訪問本站！");
}
Cookie cookie = new Cookie("lastLoginTime", System.currentTimeMillis() + "");
resp.addCookie(cookie);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
7.1. Session(重點)
package com.xiaofan.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
public class SessionServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 解決亂碼問題
req.setCharacterEncoding("utf-8");
resp.setContentType("text/html;charset=utf-8");
resp.setCharacterEncoding("utf-8");
// 得到session
HttpSession session = req.getSession();
session.setAttribute("name", "小李飛刀");
// 獲取sessionId
String sessionId = session.getId();
if (session.isNew()) {
resp.getWriter().write("session 建立成功！ID：" + sessionId);
} else {
resp.getWriter().write("session已經在伺服器中！！");
}
}
}
package com.xiaofan.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
public class SessionServlet1 extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 解決亂碼問題
req.setCharacterEncoding("utf-8");
resp.setContentType("text/html;charset=utf-8");
resp.setCharacterEncoding("utf-8");
// 得到session
HttpSession session = req.getSession();
String name = (String) session.getAttribute("name");
System.out.println(name);
}
}
package com.xiaofan.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
public class SessionServlet2 extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 得到session
HttpSession session = req.getSession();
session.removeAttribute("name");
session.invalidate();
}
}
<!--設定session預設的失效時間-->
<session-config>
<!--15分鐘後session自動失效-->
<session-timeout>15</session-timeout>
</session-config>
8 Jsp
Jstl表示式用到了查一下就可以
9. MVC三層架構
10. Filter