JWT令牌处理工具封装

在现代Web应用开发中，JWT（JSON Web Token）被广泛用于用户身份认证和信息传递。以下是一个基于Spring Boot的JWT工具类实现，支持配置化参数，并完成token生成、解析及有效性验证功能。

@Data
@Component
@ConfigurationProperties(prefix = "app.jwt")
public class JwtTokenUtil {

    private long expireMinutes; // 令牌有效期（分钟）
    private String signingKey;  // 签名密钥

    public String generateToken(Long userId) {
        return Jwts.builder()
                .setHeaderParam("typ", "JWT")
                .setSubject("user-auth")
                .setIssuedAt(new Date())
                .setExpiration(new Date(System.currentTimeMillis() + expireMinutes * 60 * 1000))
                .claim("uid", userId)
                .signWith(SignatureAlgorithm.HS512, signingKey)
                .compressWith(CompressionCodecs.DEFLATE)
                .compact();
    }

    public Long extractUserId(String token) {
        if (token == null || token.isEmpty()) {
            return null;
        }
        try {
            Claims claims = Jwts.parser()
                    .setSigningKey(signingKey)
                    .parseClaimsJws(token)
                    .getBody();
            Object uid = claims.get("uid");
            return uid instanceof Integer ? ((Integer) uid).longValue() : (Long) uid;
        } catch (JwtException | ClassCastException e) {
            return null;
        }
    }

    public boolean isTokenExpired(String token) {
        try {
            Claims claims = Jwts.parser()
                    .setSigningKey(signingKey)
                    .parseClaimsJws(token)
                    .getBody();
            return claims.getExpiration().before(new Date());
        } catch (JwtException e) {
            return true; // 解析失败视为已过期
        }
    }
}

另一个轻量级版本适用于简单场景，直接通过Map传递负载数据：

@Component
public class SimpleJwtHelper {

    private final String secretKey = "abcdefghijklmnopqrstuvwxyz1234567890";

    public String createToken(Map<String, Object> payload) {
        return Jwts.builder()
                .addClaims(payload)
                .setIssuedAt(new Date())
                .setExpiration(new Date(System.currentTimeMillis() + 1800000)) // 30分钟
                .signWith(SignatureAlgorithm.HS256, secretKey)
                .compact();
    }

    public Claims decodeToken(String token) {
        return Jwts.parser()
                .setSigningKey(secretKey)
                .parseClaimsJws(token)
                .getBody();
    }
}

数据库连接管理工具类

JDBC是Java访问关系型数据库的基础方式。为避免重复创建连接，通常会封装一个工具类来统一管理连接获取与资源释放。

public class DatabaseConnectionManager {

    private static final String DRIVER_CLASS = "com.mysql.cj.jdbc.Driver";
    private static final String DB_URL = "jdbc:mysql://localhost:3306/demo_db?useSSL=false&serverTimezone=UTC";
    private static final String USERNAME = "root";
    private static final String PASSWORD = "password";

    static {
        try {
            Class.forName(DRIVER_CLASS);
        } catch (ClassNotFoundException e) {
            throw new RuntimeException("数据库驱动加载失败", e);
        }
    }

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(DB_URL, USERNAME, PASSWORD);
    }

    public static void closeResources(Connection conn, PreparedStatement ps, ResultSet rs) {
        try {
            if (rs != null) rs.close();
            if (ps != null) ps.close();
            if (conn != null) conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

该类通过静态代码块确保驱动仅加载一次，并提供安全的连接关闭方法，防止资源泄露。

技术栈分类参考

• 传统架构：Spring + Struts + Hibernate + JSP + JBPM
• 主流MVC架构：Spring + Spring MVC + MyBatis + MySQL + Freemarker
• 微服务生态：Spring Cloud + Eureka + Ribbon + Hystrix + Zookeeper + Kafka + Redis + RabbitMQ + Jenkins + Docker
• 云原生平台：Docker + Kubernetes + KubeSphere + DevOps