Request URL: https://www.baidu.com/
Request Method: GET
Status Code: 200 OK
Remote Address: 180.101.50.242:443
Referrer Policy: unsafe-url

Accept: text/html    支持的数据类型
Accept-Encoding: gzip, deflate, br    支持的编码格式
Accept-Language: zh-CN,zh;q=0.9   语言环境
Cache-Control: max-age=0        缓存控制
Connection: keep-alive        告诉浏览器，请求完成是断开还是保持连接
HOST：主机

Bdpagetype: 1
Bdqid: 0x93f5dcf00001d517
Connection: keep-alive    连接
Content-Encoding: gzip    编码
Content-Type: text/html; 类型

Accept: text/html    支持的数据类型
Accept-Encoding: gzip, deflate, br    支持的编码格式
Accept-Language: zh-CN,zh;q=0.9   语言环境
Cache-Control: max-age=0        缓存控制
Connection: keep-alive        告诉浏览器，请求完成是断开还是保持连接
HOST：主机
Refresh:告诉客户端，多久刷新一次
Location：让网页重新定位

<?xml version="1.0" encoding="UTF-8"?>
<!--pom文件的头文文件-->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
<!--配置的GAV-->
  <groupId>org.example</groupId>
  <artifactId>javaweb-01-maven</artifactId>
  <version>1.0-SNAPSHOT</version>

  <packaging>war</packaging>
  <!--
    package项目的的包方式
    jar：Java应用
    war：Javaweb应用-->
  <name>javaweb-01-maven Maven Webapp</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

<!--配置-->
  <properties>
<!--    项目默认构建编码-->
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<!--    编码的版本-->
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
  </properties>
<!--项目依赖-->
  <dependencies>
<!--    具体的依赖配置-->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
<!--项目构建工具-->
  <build>
    <finalName>javaweb-01-maven</finalName>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.1.0</version>
        </plugin>
        <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.22.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-war-plugin</artifactId>
          <version>3.2.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>

<!--在build中配置resources，来防止资源导出失败的问题-->
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
                      http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
  version="4.0"
  metadata-complete="true">
</web-app>

public class HelloServlet extends HttpServlet {

    //由于get或者post只是请求实现方式的不同，可以互相调用，业务逻辑一样

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        ServletOutputStream outputStream = resp.getOutputStream();
        PrintWriter writer = resp.getWriter();//响应流

        writer.print("hello Servlet!");
    }

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

<!--    注册Servlet-->
    <servlet>
        <servlet-name>hello</servlet-name>
        <servlet-class>com.hwt.servlet.HelloServlet</servlet-class>
    </servlet>
<!--    Servlet的请求路径-->
    <servlet-mapping>
        <servlet-name>hello</servlet-name>
        <url-pattern>/hello</url-pattern>
    </servlet-mapping>

public class HelloServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        this.getInitParameter()   初始化参数
//        this.getServletConfig()   Servlet配置
//        this.getServletContext()  Servlet上下文

        ServletContext context = this.getServletContext();
        String username = "hwt";//数据
        context.setAttribute("username",username);//将一个数据保存在了ServletContext中，名字为：username 值为：username
    }
}

public class GetServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext context = this.getServletContext();
        String username = (String) context.getAttribute("username");

        resp.setContentType("text/html");
        resp.setCharacterEncoding("utf-8");
        resp.getWriter().print("名字"+username);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
                      http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0"
         metadata-complete="true">
  <servlet>
    <servlet-name>hello</servlet-name>
    <servlet-class>com.hwt.servlet.HelloServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>hello</servlet-name>
    <url-pattern>/hello</url-pattern>
  </servlet-mapping>
  <servlet>
    <servlet-name>getc</servlet-name>
    <servlet-class>com.hwt.servlet.GetServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>getc</servlet-name>
    <url-pattern>/getc</url-pattern>
  </servlet-mapping>
</web-app>

<!--  配置Web初始化参数-->
  <context-param>
    <param-name>url</param-name>
    <param-value>jdbc:mysql://localhost:3306/mybatis</param-value>
  </context-param>

//获取参数
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    ServletContext context = this.getServletContext();
    String url = context.getInitParameter("url");
    resp.getWriter().print(url);
}

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("进入了sd4");
        ServletContext context = this.getServletContext();
        RequestDispatcher requestDispatcher = context.getRequestDispatcher("/gp");//转发的请求路径
        requestDispatcher.forward(req,resp);//调用forward实现请求转发
    }

username=root
password=root

protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    InputStream is = this.getServletContext().getResourceAsStream("/WEB-INF/classes/db.properties");

    Properties prop = new Properties();
    prop.load(is);
    String username = prop.getProperty("username");
    String pwd = prop.getProperty("password");
    resp.getWriter().print(username+":"+pwd);
}

ServletOutputStream getOutputStream() throws IOException;
PrintWriter getWriter() throws IOException;//中文

void setCharacterEncoding(String var1);
void setContentLength(int var1);
void setContentLengthLong(long var1);
void setContentType(String var1);

    void setDateHeader(String var1, long var2);
    void addDateHeader(String var1, long var2);
    void setHeader(String var1, String var2);
    void addHeader(String var1, String var2);
    void setIntHeader(String var1, int var2);
    void addIntHeader(String var1, int var2);

    int SC_CONTINUE = 100;
    int SC_SWITCHING_PROTOCOLS = 101;
    int SC_OK = 200;
    int SC_CREATED = 201;
    int SC_ACCEPTED = 202;
    int SC_NON_AUTHORITATIVE_INFORMATION = 203;
    int SC_NO_CONTENT = 204;
    int SC_RESET_CONTENT = 205;
    int SC_PARTIAL_CONTENT = 206;
    int SC_MULTIPLE_CHOICES = 300;
    int SC_MOVED_PERMANENTLY = 301;
    int SC_MOVED_TEMPORARILY = 302;
    int SC_FOUND = 302;
    int SC_SEE_OTHER = 303;
    int SC_NOT_MODIFIED = 304;
    int SC_USE_PROXY = 305;
    int SC_TEMPORARY_REDIRECT = 307;
    int SC_BAD_REQUEST = 400;
    int SC_UNAUTHORIZED = 401;
    int SC_PAYMENT_REQUIRED = 402;
    int SC_FORBIDDEN = 403;
    int SC_NOT_FOUND = 404;
    int SC_METHOD_NOT_ALLOWED = 405;
    int SC_NOT_ACCEPTABLE = 406;
    int SC_PROXY_AUTHENTICATION_REQUIRED = 407;
    int SC_REQUEST_TIMEOUT = 408;
    int SC_CONFLICT = 409;
    int SC_GONE = 410;
    int SC_LENGTH_REQUIRED = 411;
    int SC_PRECONDITION_FAILED = 412;
    int SC_REQUEST_ENTITY_TOO_LARGE = 413;
    int SC_REQUEST_URI_TOO_LONG = 414;
    int SC_UNSUPPORTED_MEDIA_TYPE = 415;
    int SC_REQUESTED_RANGE_NOT_SATISFIABLE = 416;
    int SC_EXPECTATION_FAILED = 417;
    int SC_INTERNAL_SERVER_ERROR = 500;
    int SC_NOT_IMPLEMENTED = 501;
    int SC_BAD_GATEWAY = 502;
    int SC_SERVICE_UNAVAILABLE = 503;
    int SC_GATEWAY_TIMEOUT = 504;
    int SC_HTTP_VERSION_NOT_SUPPORTED = 505;

<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <h1>success</h1> </body> </html>

req.getParameter()//获取一个
req.getParameterValues()//获取多个

public class LoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //后台接收中文乱码问题
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        String[] hobbys = req.getParameterValues("hobbys");
        System.out.println("*******************************");
        //后台接收中文乱码问题
        System.out.println(username);
        System.out.println(password);
        System.out.println(Arrays.toString(hobbys));
        System.out.println("*******************************");
        //通过请求转发
        //这里的/代表当前的web应用
        req.getRequestDispatcher("/success.jsp").forward(req,resp);
    }

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

Cookie[] cookies = req.getCookies();//获得Cookie
cookie.getName();//获得Cookie中的key
cookie.getValue();//获得Cookie中的Value
new Cookie("lastLoginTime", System.currentTimeMillis()+"");//新建一个Cookie
cookie.setMaxAge(24*60*60);//设置Cookie有效时长
resp.addCookie(cookie);//响应给客户端

URLEncoder.encode("测试","utf-8"))
URLDecoder.decode(cookie.getValue(),"utf-8")

public class SessionDome01 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //解决乱码问题
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");

        //得到Session
        HttpSession session = req.getSession();

        //给Session中存东西
        session.setAttribute("name",new Person("测试",2));

        //获取Session的ID
        String sessionIdid = session.getId();

        //判断session是不是新创建的
        if (session.isNew()){
            resp.getWriter().write("session创建成功，ID"+sessionIdid);
        }else {
            resp.getWriter().write("session已经在服务器中存在了，ID"+sessionIdid);
        }
        //Session创建的时候做了什么事
//        Cookie cookie = new Cookie("JSESSIONID", sessionIdid);
//        resp.addCookie(cookie);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    }
}

public class SessionDome02 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //解决乱码问题
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");

        //得到Session
        HttpSession session = req.getSession();

        Person person = (Person) session.getAttribute("name");
        System.out.println(person.toString());
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    }
}

public class SessionDome03 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //解决乱码问题
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8")
        //得到Session
        HttpSession session = req.getSession();
        session.invalidate();
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    }
}

<!--    设置Session默认的失效时间-->
    <session-config>
<!--        15分钟后Session自动失效，以分钟为单位-->
        <session-timeout>15</session-timeout>
    </session-config>

//初始化
  public void _jspInit() {
  }
//销毁
  public void _jspDestroy() {
  }
//jspService
  public void _jspService(HttpServletRequest request, HttpServletResponse response) {

 out.write("<h2>Hello World!</h2>\n");

    <%--  JSP表达式
    作用：用来将程序的输出输出到客户端
    <%= 变量或者表达式 %>
    --%>
  <%= new java.util.Date() %>

  <%
    int sum = 0;
    for (int i = 0; i <= 100; i++) {
      sum+=i;
    }
    out.println("<h1>Sum = "+sum+"</h1>");
  %>

  <%
    int x = 10;
    out.println(x);
  %>
    <p>JSP文档</p>
  <%
    int y = 2;
    out.println(x);
    out.println(y);
  %>
  <hr>
<%--  在代码中嵌入HTML元素--%>
  <%
    for (int i = 0; i < 5; i++) {
  %>
    <h1>hello <%=i%></h1>
  <%
    }
  %>

<%!
  static {
    System.out.println("加载中");
  }
  private int a = 0;
  public void hwt(){
    System.out.println("hwt");
  }
%>

<%%>
<%=%>
<%!%>
<%--注释--%>

<%@page args... %>

    <%--@include会将两个页面合并
        会导致变量冲突
    --%>
    <%@include file="common/header.jsp"%>
    <h1>主体</h1>
    <%@include file="common/footer.jsp"%>

    <hr>

    <%--
    jsp标签
    jsp:include:拼接页面，本质还是三个
    --%>
    <jsp:include page="common/header.jsp"/>
    <h1>网页主体</h1>
    <jsp:include page="common/footer.jsp"/>

 <dependency>
            <groupId>javax.servlet.jsp.jstl</groupId>
            <artifactId>jstl-api</artifactId>
            <version>1.2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/taglibs/standard -->
<!--        standard标签库-->
        <dependency>
            <groupId>taglibs</groupId>
            <artifactId>standard</artifactId>
            <version>1.1.2</version>
        </dependency>

<jsp:forward page="/jsptag2.jsp">
    <jsp:param name="name" value="ceshi"/>
    <jsp:param name="password" value="root"/>
</jsp:forward>

<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>//引入标签

<body>
<h4>测试c：if</h4>
<form action="coreif.jsp" method="get">
    <%--
        el表达式获取表单中的数据
        ${param.参数名}
    --%>
    <input type="text" name="username" value="${param.username}"/>
    <input type="submit" value="登录">
</form>

<%--判断提交的是管理员，则登陆成功--%>
<c:if test="${param.username=='admin'}" var="isAdmin">
    <c:out value="管理员欢迎您"/>
</c:if>
<c:out value="${isAdmin}"/>

</body>

<%
    ArrayList<String> people = new ArrayList<>();
    people.add(0,"张三");
    people.add(1,"李四");
    people.add(2,"王五");
    people.add(3,"赵六");
    request.setAttribute("list", people);
%>
<%--
var,    每一次遍历出来的变量
items， 要遍历的对象
begin,  哪里开始
end,    到哪里
step，  步长
--%>
<c:forEach var="people" items="${list}">
    <c:out value="${people}"/><br>
</c:forEach>
<hr>

<c:forEach var="people" items="${list}" begin="1" end="3" step="2">
    <c:out value="${people}"/><br>
</c:forEach>

class People{
    private int id;
    private String name;
    private int age;
    private String address;
}
class A{
    new People(1,"张三",3"南京");
}

servlet--CRUD-->数据库
弊端：程序十分臃肿，不利于维护
servlet代码中：处理请求、响应、视图跳转、处理JDBC、处理业务代码、处理逻辑代码
    
   架构：没有什么是加一层解决不了的

登录—>接收用户登录请求—>处理用户请求（获取用户登录的参数，username，password）交给业务层处理登录业务（判断账号密码是否正确：事务）—>Dao层查询用户名和密码是否正确—>数据库

public class TestPanel {
    public static void main(String[] args) {
        Frame frame = new Frame("测试");//创建一个窗体
        Panel panel = new Panel(null);//面板
        frame.setLayout(null);//设置窗体布局

        frame.setBounds(300,300,500,500);
        frame.setBackground(new Color(0,0,255));//设置背景颜色
        panel.setBounds(50,50,300,300);
        panel.setBackground(new Color(0,255,0));//设置背景颜色
        frame.add(panel);
        frame.setVisible(true);

        //监听事件，监听关闭事件
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.out.println("关闭ing");
            }
        });
    }
}

CREATE TABLE users(
id INT PRIMARY KEY,
`name` VARCHAR(40),
`password` VARCHAR(40),
email VARCHAR(60),
birthday DATE
);

INSERT INTO users(id,`name`,`password`,email,birthday)
VALUES(1,'张三','123456','zs@qq.com','2000-01-01');

INSERT INTO users(id,`name`,`password`,email,birthday)
VALUES(2,'李四','123456','ls@qq.com','2000-01-01');

INSERT INTO users(id,`name`,`password`,email,birthday)
VALUES(3,'王五','123456','ww@qq.com','2000-01-01');

SELECT * FROM users

    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.28</version>
        </dependency>
    </dependencies>

public class Testjdbc {
    public static void main(String[] args) throws ClassNotFoundException, SQLException {
        //配置信息
        String url = "jdbc:mysql://localhost:3306/jdbc?userUnicode=true&characterEncoding=utf-8";
        String username = "root";
        String password = "root";
        //1.加载驱动
        Class.forName("com.mysql.cj.jdbc.Driver");
        //2.连接数据库
        Connection connection = DriverManager.getConnection(url, username, password);
        Statement statement = connection.createStatement();
        //4.编写sql
        String sql = "select * from users";
        //5.执行sql
        ResultSet rs = statement.executeQuery(sql);
        while (rs.next()){
            System.out.println("id"+rs.getObject("id"));
            System.out.println("name"+rs.getObject("name"));
            System.out.println("password"+rs.getObject("password"));
            System.out.println("email"+rs.getObject("email"));
            System.out.println("birthday"+rs.getObject("birthday"));
        }
        //6.关闭连接，释放资源
        rs.close();
        statement.close();
        connection.close();
    }
}

开启事务
    事务提交    commit()
    事务回滚    rollback()
关闭事务
    
转账
    A：1000
    B：1000
 经过转账后：两种情况 A：900    B：1100
                  A：1000  B：1000
    

public class Testjdbc2 {
    public static void main(String[] args) throws SQLException {
        //配置信息
        String url = "jdbc:mysql://localhost:3306/jdbc?userUnicode=true&characterEncoding=utf-8";
        String username = "root";
        String password = "root";
        Connection connection = null;
        //1.加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.连接数据库
            connection = DriverManager.getConnection(url, username, password);
            //3.通知数据库开启事务，false 开启
            connection.setAutoCommit(false);

            String sql = "update account set money = money - 100 where name = 'A';";
            connection.prepareStatement(sql).executeUpdate();
            //错误
//            int i = 1 / 0;
            String sql2 = "update account set money = money + 100 where name = 'B';";
            connection.prepareStatement(sql2).executeUpdate();
            connection.commit();//两条都执行成功，才会提交事务
            System.out.println("success");
        } catch (Exception e) {
            try {
                connection.rollback();
                e.printStackTrace();
            } catch (SQLException ex) {
                ex.printStackTrace();
            }
        }finally {
            connection.close();
        }
    }
}