Some re-factoring for lazy loading

beehive-jdbc-mapper/src/main/java/com/moparisthebest/jdbc/CompilingRowToObjectMapper.java

@@ -48,6 +48,7 @@ public class CompilingRowToObjectMapper<T> extends RowToObjectMapper<T> {
 				this.keys = null;
 				this._fields = null;
 				this._fieldTypes = null;
+				this.constructor = null;
 			} else {
 				//System.out.printf("cache hit, keys: %s\n", keys);
 				// load from cache
@@ -144,6 +145,8 @@ public class CompilingRowToObjectMapper<T> extends RowToObjectMapper<T> {
 
 	protected void gen(final StringBuilder java, final String tType) {
 
+		lazyLoadConstructor();
+
 		if (resultSetConstructor) {
 			java.append("return new ").append(tType).append("(rs);\n");
 			return;

beehive-jdbc-mapper/src/main/java/com/moparisthebest/jdbc/RowMapper.java

@@ -52,6 +52,8 @@ public abstract class RowMapper {
     /** Class to map ResultSet Rows to. */
     protected final Class<?> _returnTypeClass;
 
+    protected final int _columnCount;
+
     /**
      * Create a new RowMapper for the specified ResultSet and return type Class.
      * @param resultSet ResultSet to map
@@ -62,6 +64,12 @@ public abstract class RowMapper {
         _resultSet = resultSet;
         _returnTypeClass = returnTypeClass;
         _cal = cal;
+
+        try {
+            _columnCount = resultSet.getMetaData().getColumnCount();
+        } catch (SQLException e) {
+            throw new MapperException("RowToObjectMapper: SQLException: " + e.getMessage(), e);
+        }
     }
 
     /**
@@ -80,10 +88,9 @@ public abstract class RowMapper {
 
         String[] keys;
         final ResultSetMetaData md = _resultSet.getMetaData();
-        final int columnCount = md.getColumnCount();
 
-        keys = new String[columnCount + 1];
-        for (int i = 1; i <= columnCount; i++) {
+        keys = new String[_columnCount + 1];
+        for (int i = 1; i <= _columnCount; i++) {
             keys[i] = md.getColumnName(i).toUpperCase();
         }
         return keys;

beehive-jdbc-mapper/src/main/java/com/moparisthebest/jdbc/RowToObjectMapper.java

@@ -52,16 +52,15 @@ public class RowToObjectMapper<T> extends RowMapper {
 	public static final int TYPE_BOOLEAN = _tmf.getTypeId(Boolean.TYPE);//TypeMappingsFactory.TYPE_BOOLEAN; // not public? 
 	public static final int TYPE_BOOLEAN_OBJ = _tmf.getTypeId(Boolean.class);//TypeMappingsFactory.TYPE_BOOLEAN_OBJ; // not public?
 
-	protected final int _columnCount;
-	protected final boolean resultSetConstructor;
-	protected final Constructor<T> constructor;
+	protected boolean resultSetConstructor, constructorLoaded = false;
+	protected Constructor<? extends T> constructor;
 	protected final Class<? extends T> _returnTypeClass; // over-ride non-generic version of this in super class
 	
 	// only non-null when _returnTypeClass is an array, or a map
 	protected final Class<?> componentType;
 	protected final boolean returnMap;
 
-	protected AccessibleObject[] _fields;
+	protected AccessibleObject[] _fields = null;
 	protected int[] _fieldTypes;
 
 	protected final Object[] _args = new Object[1];
@@ -96,38 +95,35 @@ public class RowToObjectMapper<T> extends RowMapper {
 			// detect if we want an array back
 			componentType = returnTypeClass.getComponentType();
 		}
+	}
 
-		_fields = null;
-
-		try {
-			_columnCount = resultSet.getMetaData().getColumnCount();
-		} catch (SQLException e) {
-			throw new MapperException("RowToObjectMapper: SQLException: " + e.getMessage(), e);
-		}
-
+	protected void lazyLoadConstructor() {
+		if(constructorLoaded)
+			return;
 		// detect if returnTypeClass has a constructor that takes a ResultSet, if so, our job couldn't be easier...
 		boolean resultSetConstructor = false;
-		Constructor<T> constructor = null;
+		Constructor<? extends T> constructor = null;
 		try {
-			constructor = returnTypeClass.getConstructor(ResultSet.class);
+			constructor = _returnTypeClass.getConstructor(ResultSet.class);
 			if (!constructor.isAccessible())
 				constructor.setAccessible(true);
 			resultSetConstructor = true;
 		} catch (Throwable e) {
 			// if no resultSetConstructor find the constructor
 			try {
-				constructor = returnTypeClass.getDeclaredConstructor();
+				constructor = _returnTypeClass.getDeclaredConstructor();
 				if (!constructor.isAccessible())
 					constructor.setAccessible(true);
 			} catch (Throwable e1) {
 				// if column count is 2 or less, it might map directly to a type like a Long or something, or be a map which does
 				// or if componentType is non-null, then we want an array like Long[] or String[]
 				if(_columnCount > 2 && componentType == null)
-					throw new MapperException("Exception when trying to get constructor for : "+returnTypeClass.getName() + " Must have default no-arg constructor or one that takes a single ResultSet.", e1);
+					throw new MapperException("Exception when trying to get constructor for : "+_returnTypeClass.getName() + " Must have default no-arg constructor or one that takes a single ResultSet.", e1);
 			}
 		}
 		this.resultSetConstructor = resultSetConstructor;
 		this.constructor = constructor;
+		this.constructorLoaded = true;
 	}
 
 	/**
@@ -148,6 +144,8 @@ public class RowToObjectMapper<T> extends RowMapper {
 	@SuppressWarnings({"unchecked"})
 	public T mapRowToReturnType() {
 
+		lazyLoadConstructor();
+
 		if (resultSetConstructor)
 			try {
 				return constructor.newInstance(_resultSet);