Система вложенных тегов (ECI), связь с базой данных

src/main/java/com/rosetta/im/database/DatabaseManager.java

@@ -3,6 +3,7 @@ package com.rosetta.im.database;
 import org.hibernate.Session;
 import org.hibernate.Transaction;
 
+import java.util.HashMap;
 import java.util.List;
 
 public class DatabaseManager {
@@ -61,6 +62,28 @@ public class DatabaseManager {
         }
     }
 
+    public static <T> T findBy(Class<T> entity, HashMap<String, Object> params) {
+        Session session = HibernateUtil.openSession();
+        try {
+            StringBuilder queryString = new StringBuilder("FROM " + entity.getSimpleName() + " WHERE ");
+            int index = 0;
+            for (String key : params.keySet()) {
+                if (index > 0) {
+                    queryString.append(" AND ");
+                }
+                queryString.append(key).append(" = :").append(key);
+                index++;
+            }
+            var query = session.createQuery(queryString.toString(), entity);
+            for (var entry : params.entrySet()) {
+                query.setParameter(entry.getKey(), entry.getValue());
+            }
+            return query.uniqueResult();
+        } finally {
+            session.close();
+        }
+    }
+
     public static <T> void delete(T entity) {
         Session session = HibernateUtil.openSession();
         Transaction transaction = null;

src/main/java/com/rosetta/im/database/entity/User.java

@@ -43,9 +43,6 @@ public class User extends BaseEntity {
 	@Column(name = "publicKey", nullable = false, unique = true)
 	private String publicKey;
 
-	@Column(name = "timestamp", nullable = false)
-	private long timestamp;
-
 	@Column(name = "createdTime", nullable = false, updatable = false)
 	private Date createdTime;
 
@@ -104,14 +101,6 @@ public class User extends BaseEntity {
 		this.publicKey = publicKey;
 	}
 
-	public long getTimestamp() {
-		return timestamp;
-	}
-
-	public void setTimestamp(long timestamp) {
-		this.timestamp = timestamp;
-	}
-
 	public Date getCreatedTime() {
 		return createdTime;
 	}