애플리케이션 보안을 향상시키기 위해 Java 보안 메커니즘을 강화하는 방법은 무엇입니까?

import java.security.cert.X509Certificate;
import java.security.cert.CertificateFactory;
import java.io.FileInputStream;
import java.io.File;

public class CodeSigningExample {
  public static void main(String[] args) throws Exception {
    File jarFile = new File("my_app.jar");

    // 创建证书工厂
    CertificateFactory cf = CertificateFactory.getInstance("X.509");

    // 从 JAR 文件中提取证书
    X509Certificate cert = (X509Certificate) cf.generateCertificate(new FileInputStream(jarFile));

    // 验证证书
    cert.verify(cert.getPublicKey());

    System.out.println("证书已验证！");
  }
}

import java.security.SecurityManager;

public class SecurityManagerExample extends SecurityManager {
  @Override
  public void checkPermission(Permission perm) {
    // 根据需要允许或拒绝权限
  }
}

public static void main(String[] args) {
  // 安装安全管理器
  System.setSecurityManager(new SecurityManagerExample());

  // 执行受限操作
  // 这里会抛出 SecurityException
}

import org.apache.shiro.SecurityUtils;
import org.apache.shiro.subject.Subject;

public class ShiroExample {
  public static void main(String[] args) {
    // 获取主体
    Subject subject = SecurityUtils.getSubject();

    // 认证用户
    subject.login(new UsernamePasswordToken("username", "password"));

    // 检查用户是否有权限
    subject.checkPermission("permission:read");

    // 执行受限操作
  }
}

<beans:beans xmlns="http://www.springframework.org/schema/beans"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

  <security:http auto-config="true"/>
  <security:authentication-manager>
    <security:authentication-provider>
      <security:user-service>
        <security:user name="admin" password="admin" authorities="ROLE_ADMIN"/>
      </security:user-service>
    </security:authentication-provider>
  </security:authentication-manager>
</beans:beans>