package lee;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.*;

@WebFilter(
    filterName="authority", 
    urlPatterns={"/*"}, 
    initParams={
        @WebInitParam(name="encoding", value="GBK"),
        @WebInitParam(name="loginPage", value="/login.jsp"),
        @WebInitParam(name="proLogin", value="/proLogin.jsp")
    }
)
public class AuthorityFilter implements Filter
{
    // FilterConfig可用于访问Filter的配置信息
    private FilterConfig config;
    // 实现初始化方法
    public void init(FilterConfig config)
    {
        this.config = config;
    }
    // 实现销毁方法
    public void destroy()
    {
        this.config = null;
    }
    // 执行过滤的核心方法
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
        throws IOException,ServletException
    {
        // 获取该Filter的配置参数
        String encoding = config.getInitParameter("encoding");
        String loginPage = config.getInitParameter("loginPage");
        String proLogin = config.getInitParameter("proLogin");
        // 设置request编码用的字符集
        request.setCharacterEncoding(encoding);            // ①
        HttpServletRequest requ = (HttpServletRequest)request;
        HttpSession session = requ.getSession(true);
        // 获取客户请求的页面
        String requestPath = requ.getServletPath();
        // 如果session范围的user为null，
        // 且用户请求的既不是登录页面，也不是处理登录的页面
        if( session.getAttribute("user") == null
            && !requestPath.endsWith(loginPage)
            && !requestPath.endsWith(proLogin))
        {
            // forward到登录页面
            request.setAttribute("tip" , "您还没有登录");
            request.getRequestDispatcher(loginPage).forward(request, response);
        }
        // "放行"请求
        else
        {
            chain.doFilter(request, response);
        }
    }
}

String encoding = config.getInitParameter("encoding");
String loginPage = config.getInitParameter("loginPage");
String proLogin = config.getInitParameter("proLogin");

request.setCharacterEncoding(encoding);

if( session.getAttribute("user") == null
    && !requestPath.endsWith(loginPage)
    && !requestPath.endsWith(proLogin))
{
    // forward到登录页面
    request.setAttribute("tip" , "您还没有登录");
    request.getRequestDispatcher(loginPage).forward(request, response);
}
// "放行"请求
else
{
    chain.doFilter(request, response);
}

<!-- 定义Filter -->
<filter>
    <!-- Filter的名字 -->
    <filter-name>authority</filter-name>
    <!-- Filter的实现类 -->
    <filter-class>lee.AuthorityFilter</filter-class>
    <!-- 下面三个init-param元素配置了三个参数 -->
    <init-param>
        <param-name>encoding</param-name>
        <param-value>GBK</param-value>
    </init-param>
    <init-param>
        <param-name>loginPage</param-name>
        <param-value>/login.jsp</param-value>
    </init-param>
    <init-param>
        <param-name>proLogin</param-name>
        <param-value>/proLogin.jsp</param-value>
    </init-param>
</filter>

package lee;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.*;

@WebFilter(filterName = "log", urlPatterns = { "/*" })
public class LogFilter implements Filter {
    // FilterConfig可用于访问Filter的配置信息
    private FilterConfig config;

    // 实现初始化方法
    public void init(FilterConfig config) {
        this.config = config;
    }

    // 实现销毁方法
    public void destroy() {
        this.config = null;
    }

    // 执行过滤的核心方法
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        // ---------下面代码用于对用户请求执行预处理---------
        // 获取ServletContext对象，用于记录日志
        ServletContext context = this.config.getServletContext();
        long before = System.currentTimeMillis();
        System.out.println("开始过滤...");
        // 将请求转换成HttpServletRequest请求
        HttpServletRequest hrequest = (HttpServletRequest) request;
        // 输出提示信息
        System.out.println("Filter已经截获到用户的请求的地址： " + hrequest.getServletPath());
        // Filter只是链式处理，请求依然放行到目的地址
        chain.doFilter(request, response);
        // ---------下面代码用于对服务器响应执行后处理---------
        long after = System.currentTimeMillis();
        // 输出提示信息
        System.out.println("过滤结束");
        // 输出提示信息
        System.out.println("请求被定位到" + hrequest.getRequestURI() + "   所花的时间为: " + (after - before));
    }
}

package lee;

import javax.servlet.jsp.tagext.*;
import javax.servlet.jsp.*;
import java.io.*;
import java.util.*;

public class DynaAttributesTag extends SimpleTagSupport 
            implements DynamicAttributes {
    // 保存每个属性名的集合
    private ArrayList<String> keys = new ArrayList<String>();
    // 保存每个属性值的集合
    private ArrayList<Object> values = new ArrayList<Object>();

    @Override
    public void doTag() throws JspException, IOException {
        JspWriter out = getJspContext().getOut();
        // 此处只是简单地输出每个属性
        out.println("<ol>");
        for (int i = 0; i < keys.size(); i++) {
            String key = keys.get(i);
            Object value = values.get(i);
            out.println("<li>" + key + " = " + value + "</li>");
        }
        out.println("</ol>");
    }

    @Override
    public void setDynamicAttribute(String uri, String localName, Object value) 
            throws JspException {
        // 添加属性名
        keys.add(localName);
        // 添加属性值
        values.add(value);
    }
}

package lee;

import javax.servlet.jsp.tagext.*;
import javax.servlet.jsp.*;
import java.io.*;

public class FragmentTag extends SimpleTagSupport {
    private JspFragment fragment;

    // fragment的setter和getter方法
    public void setFragment(JspFragment fragment) {
        this.fragment = fragment;
    }

    public JspFragment getFragment() {
        return this.fragment;
    }

    @Override
    public void doTag() throws JspException, IOException {
        JspWriter out = getJspContext().getOut();
        out.println("<div style='padding:10px;border:1px solid black;" + ";border-radius:20px'>");
        out.println("<h3>下面是动态传入的JSP片段</h3>");
        // 调用、输出“页面片段”
        fragment.invoke(null);
        out.println("</div");
    }
}

package lee;

import javax.servlet.jsp.tagext.*;
import javax.servlet.jsp.*;
import java.io.*;
import java.sql.*;

public class QueryTag extends SimpleTagSupport {
    // 定义成员变量来代表标签的属性
    private String driver;
    private String url;
    private String user;
    private String pass;
    private String sql;

    // driver的setter和getter方法
    public void setDriver(String driver) {
        this.driver = driver;
    }

    public String getDriver() {
        return this.driver;
    }

    // url的setter和getter方法
    public void setUrl(String url) {
        this.url = url;
    }

    public String getUrl() {
        return this.url;
    }

    // user的setter和getter方法
    public void setUser(String user) {
        this.user = user;
    }

    public String getUser() {
        return this.user;
    }

    // pass的setter和getter方法
    public void setPass(String pass) {
        this.pass = pass;
    }

    public String getPass() {
        return this.pass;
    }

    // sql的setter和getter方法
    public void setSql(String sql) {
        this.sql = sql;
    }

    public String getSql() {
        return this.sql;
    }

    // 执行数据库访问的对象
    private Connection conn = null;
    private Statement stmt = null;
    private ResultSet rs = null;
    private ResultSetMetaData rsmd = null;
    
    // conn的setter和getter方法
    public void setConn(Connection conn) {
        this.conn = conn;
    }

    public Connection getConn() {
        return this.conn;
    }

    // stmt的setter和getter方法
    public void setStmt(Statement stmt) {
        this.stmt = stmt;
    }

    public Statement getStmt() {
        return this.stmt;
    }

    // rs的setter和getter方法
    public void setRs(ResultSet rs) {
        this.rs = rs;
    }

    public ResultSet getRs() {
        return this.rs;
    }

    // rsmd的setter和getter方法
    public void setRsmd(ResultSetMetaData rsmd) {
        this.rsmd = rsmd;
    }

    public ResultSetMetaData getRsmd() {
        return this.rsmd;
    }


    public void doTag() throws JspException, IOException {
        try {
            // 注册驱动
            Class.forName(driver);
            // 获取数据库连接
            conn = DriverManager.getConnection(url, user, pass);
            // 创建Statement对象
            stmt = conn.createStatement();
            // 执行查询
            rs = stmt.executeQuery(sql);
            rsmd = rs.getMetaData();
            // 获取列数目
            int columnCount = rsmd.getColumnCount();
            // 获取页面输出流
            Writer out = getJspContext().getOut();
            // 在页面输出表格
            out.write("<table border='1' bgColor='#9999cc' width='400'>");
            // 遍历结果集
            while (rs.next()) {
                out.write("<tr>");
                // 逐列输出查询到的数据
                for (int i = 1; i <= columnCount; i++) {
                    out.write("<td>");
                    out.write(rs.getString(i));
                    out.write("</td>");
                }
                out.write("</tr>");
            }
        } catch (ClassNotFoundException cnfe) {
            cnfe.printStackTrace();
            throw new JspException("自定义标签错误" + cnfe.getMessage());
        } catch (SQLException ex) {
            ex.printStackTrace();
            throw new JspException("自定义标签错误" + ex.getMessage());
        } finally {
            // 关闭结果集
            try {
                if (rs != null)
                    rs.close();
                if (stmt != null)
                    stmt.close();
                if (conn != null)
                    conn.close();
            } catch (SQLException sqle) {
                sqle.printStackTrace();
            }
        }
    }
}

package lee;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.PrintWriter;
import java.io.IOException;
import java.sql.*;

@WebServlet(
    name = "login",
    urlPatterns =
    {"/login"})
public class LoginServlet extends HttpServlet
{
    // 响应客户端请求的方法
    public void service(HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, java.io.IOException
    {
        String errMsg = "";
        // Servlet本身并不输出响应到客户端，因此必须将请求转发到视图页面
        RequestDispatcher rd;
        // 获取请求参数
        String username = request.getParameter("username");
        String pass = request.getParameter("pass");
        try
        {
            // Servlet本身并不执行任何的业务逻辑处理，它调用JavaBean处理用户请求
            // MySQL5.0
            // DbDao dd = new DbDao("com.mysql.jdbc.Driver",
            // "jdbc:mysql://localhost:3306/liuyan", "root", "32147");
            // Mysql8.0
            DbDao dd = new DbDao("com.mysql.cj.jdbc.Driver",
                    "jdbc:mysql://localhost:3306/liuyan?serverTimezone=GMT",
                    "root", "root");

            // 查询结果集
            ResultSet rs = dd.query(
                    "select pass from user_inf" + " where name = ?", username);
            if (rs.next())
            {
                // 用户名和密码匹配
                if (rs.getString("pass").equals(pass))
                {
                    // 获取session对象
                    HttpSession session = request.getSession(true);
                    // 设置session属性，跟踪用户会话状态
                    session.setAttribute("name", username);
                    // 获取转发对象
                    rd = request.getRequestDispatcher("/welcome.jsp");
                    // 转发请求
                    rd.forward(request, response);
                } else
                {
                    // 用户名和密码不匹配时
                    errMsg += "您的用户名密码不符合,请重新输入";
                }
            } else
            {
                // 用户名不存在时
                errMsg += "您的用户名不存在,请先注册";
            }
        } catch (Exception e)
        {
            e.printStackTrace();
        }
        // 如果出错，转发到重新登录
        if (errMsg != null && !errMsg.equals(""))
        {
            rd = request.getRequestDispatcher("/login.jsp");
            request.setAttribute("err", errMsg);
            rd.forward(request, response);
        }
    }
}

package lee;

import java.sql.*;

public class DbDao {
    private Connection conn;
    private String driver;
    private String url;
    private String username;
    private String pass;

    public DbDao() {
    }

    public DbDao(String driver, String url, String username, String pass) {
        this.driver = driver;
        this.url = url;
        this.username = username;
        this.pass = pass;
    }

    // 下面是各个成员属性的setter和getter方法
    public void setDriver(String driver) {
        this.driver = driver;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public void setPass(String pass) {
        this.pass = pass;
    }

    public String getDriver() {
        return (this.driver);
    }

    public String getUrl() {
        return (this.url);
    }

    public String getUsername() {
        return (this.username);
    }

    public String getPass() {
        return (this.pass);
    }

    // 获取数据库连接
    public Connection getConnection() throws Exception {
        if (conn == null) {
            Class.forName(this.driver);
            conn = DriverManager.getConnection(url, username, this.pass);
        }
        return conn;
    }

    // 插入记录
    public boolean insert(String sql, Object... args) throws Exception {
        PreparedStatement pstmt = getConnection().prepareStatement(sql);
        for (int i = 0; i < args.length; i++) {
            pstmt.setObject(i + 1, args[i]);
        }
        if (pstmt.executeUpdate() != 1) {
            return false;
        }
        pstmt.close();
        return true;
    }

    // 执行查询
    public ResultSet query(String sql, Object... args) throws Exception {
        PreparedStatement pstmt = getConnection().prepareStatement(sql);
        for (int i = 0; i < args.length; i++) {
            pstmt.setObject(i + 1, args[i]);
        }
        return pstmt.executeQuery();
    }

    // 执行修改
    public void modify(String sql, Object... args) throws Exception {
        PreparedStatement pstmt = getConnection().prepareStatement(sql);
        for (int i = 0; i < args.length; i++) {
            pstmt.setObject(i + 1, args[i]);
        }
        pstmt.executeUpdate();
        pstmt.close();
    }

    // 关闭数据库连接的方法
    public void closeConn() throws Exception {
        if (conn != null && !conn.isClosed()) {
            conn.close();
        }
    }
}

package lee;

import java.sql.*;
import javax.servlet.http.*;
import javax.servlet.*;
import javax.servlet.annotation.*;
import java.io.*;

@WebServlet(
    name = "testServlet", 
    urlPatterns = { "/testServlet" }, 
    initParams = {
        @WebInitParam(name = "driver", value = "com.mysql.jdbc.Driver"),
        @WebInitParam(name = "url", value = "jdbc:mysql://localhost:3306/javaee"),
        @WebInitParam(name = "user", value = "root"), 
        @WebInitParam(name = "pass", value = "32147") }
)
public class TestServlet extends HttpServlet {
    // 重写init方法
    public void init(ServletConfig config) throws ServletException {
        // 重写该方法，应该首先调用父类的init()方法
        super.init(config);
    }

    // 响应客户端请求的方法
    public void service(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, java.io.IOException {
        try {
            // 获取ServletConfig对象
            ServletConfig config = getServletConfig();
            // 通过ServletConfig对象获取配置参数：dirver
            String driver = config.getInitParameter("driver");
            // 通过ServletConfig对象获取配置参数：url
            String url = config.getInitParameter("url");
            // 通过ServletConfig对象获取配置参数：user
            String user = config.getInitParameter("user");
            // 通过ServletConfig对象获取配置参数：pass
            String pass = config.getInitParameter("pass");
            // 注册驱动
            Class.forName(driver);
            // 获取数据库连接
            Connection conn = DriverManager.getConnection(url, user, pass);
            // 创建Statement对象
            Statement stmt = conn.createStatement();
            // 执行查询，获取ResuletSet对象
            ResultSet rs = stmt.executeQuery("select * from news_inf");
            response.setContentType("text/html;charSet=gbk");
            // 获取页面输出流
            PrintStream out = new PrintStream(response.getOutputStream());
            // 输出HTML标签
            out.println("<html>");
            out.println("<head>");
            out.println("<title>访问Servlet初始化参数测试</title>");
            out.println("</head>");
            out.println("<body>");
            out.println("<table bgcolor=\"#9999dd\" border=\"1\"" + "width=\"480\">");
            // 遍历结果集
            while (rs.next()) {
                // 输出结果集内容
                out.println("<tr>");
                out.println("<td>" + rs.getString(1) + "</td>");
                out.println("<td>" + rs.getString(2) + "</td>");
                out.println("</tr>");
            }
            out.println("</table>");
            out.println("</body>");
            out.println("</html>");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

package lee;

import javax.servlet.http.*;
import javax.servlet.*;
import javax.servlet.annotation.*;

import javax.swing.*;
import java.awt.event.*;
import java.util.Date;

@WebServlet(loadOnStartup = 1)
public class TimerServlet extends HttpServlet {
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        Timer t = new Timer(1000, new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                System.out.println(new Date());
            }
        });
        t.start();
    }
}

@WebServlet(loadOnStartup = 1)