如何设置dirContextValidator？

import javax.naming.Context;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;
import javax.naming.directory.Attributes;
import javax.naming.directory.BasicAttributes;
import javax.naming.directory.Attribute;
import java.util.Properties;

public class DirContextValidatorExample {
    public static void main(String[] args) {
        try {
            // 设置LDAP服务器连接参数
            Properties properties = new Properties();
            properties.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");
            properties.put(Context.PROVIDER_URL, "ldap://ldap.example.com:389");
            properties.put(Context.SECURITY_AUTHENTICATION, "simple");
            properties.put(Context.SECURITY_PRINCIPAL, "cn=admin,dc=example,dc=com");
            properties.put(Context.SECURITY_CREDENTIALS, "password");

            // 创建目录上下文对象并进行身份验证
            DirContext context = new InitialDirContext(properties);

            // 验证连接是否成功
            Attributes attributes = context.getAttributes("");
            Attribute attribute = attributes.get("cn");
            if (attribute != null) {
                System.out.println("Connection successful!");
            } else {
                System.out.println("Connection failed!");
            }

            // 关闭目录上下文
            context.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}