public class CharacterEncodingFilter implements Filter {
private String encoding;

@Override
public void init(FilterConfig filterConfig) throws ServletException {
encoding = filterConfig.getInitParameter(“encoding”);
if (encoding == null) {
encoding = “UTF-8”;
}
}

@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
request.setCharacterEncoding(encoding);
response.setCharacterEncoding(encoding);
chain.doFilter(request, response);
}

@Override
public void destroy() {
}
}

public class MyContextListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent sce) {
System.out.println(“Web application initialized”);
// 初始化操作，如加载配置文件、连接池等
}

@Override
public void contextDestroyed(ServletContextEvent sce) {
System.out.println(“Web application destroyed”);
// 清理操作，如关闭连接池等
}
}

public class JdbcExample {
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;

try {
// 加载驱动
Class.forName(“com.mysql.cj.jdbc.Driver”);

// 建立连接
conn = DriverManager.getConnection(
“jdbc:mysql://fgedudb:3306/test”,
“root”,
“password”
);

// 创建Statement
stmt = conn.createStatement();

// 执行查询
rs = stmt.executeQuery(“SELECT * FROM users”);

// 处理结果集
while (rs.next()) {
int id = rs.getInt(“id”);
String name = rs.getString(“name”);
String email = rs.getString(“email”);
System.out.println(“ID: ” + id + “, Name: ” + name + “, Email: ” + email);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
// 关闭资源
try {
if (rs != null) rs.close();
if (stmt != null) stmt.close();
if (conn != null) conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}

// 构造方法、getter和setter方法
public User() {}

public User(int id, String name, String email) {
this.id = id;
this.name = name;
this.email = email;
}

// getter和setter方法
public int getId() { return id; }
public void setId(int id) { this.id = id; }
public String getName() { return name; }
public void setName(String name) { this.name = name; }
public String getEmail() { return email; }
public void setEmail(String email) { this.email = email; }
}

// Controller
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;

public class UserController extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 模拟获取用户数据
User user = new User(1, “John Doe”, “john@fgedu.net.cn”);

// 将数据设置到请求属性
request.setAttribute(“user”, user);

// 转发到视图
RequestDispatcher dispatcher = request.getRequestDispatcher(“user.jsp”);
dispatcher.forward(request, response);
}
}

// View (user.jsp)
<%@ page contentType="text/html;charset=UTF-8" language="java" %>

User Detail

ID: ${user.id}

Name: ${user.name}

Email: ${user.email}

# 配置环境变量
# vi /etc/profile
export CATALINA_HOME=/usr/local/tomcat
export PATH=$CATALINA_HOME/bin:$PATH

# 启动Tomcat
# $CATALINA_HOME/bin/startup.sh

# 查看Tomcat状态
# ps aux | grep tomcat

# 访问Tomcat管理界面
# 浏览器访问: http://fgedudb:8080

public class SecureJdbcExample {
public static void getUserById(int id) {
Connection conn = null;
PreparedStatement pstmt = null;
ResultSet rs = null;

try {
// 加载驱动
Class.forName(“com.mysql.cj.jdbc.Driver”);

// 建立连接
conn = DriverManager.getConnection(
“jdbc:mysql://fgedudb:3306/test”,
“root”,
“password”
);

// 使用PreparedStatement防止SQL注入
String sql = “SELECT * FROM users WHERE id = ?”;
pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, id);

// 执行查询
rs = pstmt.executeQuery();

// 处理结果集
while (rs.next()) {
System.out.println(“ID: ” + rs.getInt(“id”) + “, Name: ” + rs.getString(“name”));
}
} catch (Exception e) {
e.printStackTrace();
} finally {
// 关闭资源
try {
if (rs != null) rs.close();
if (pstmt != null) pstmt.close();
if (conn != null) conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}