LiteralExpression.java :  » Database-ORM » hibernate » org » hibernate » ejb » criteria » expression » Java Open Source

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hibernate » org » hibernate » ejb » criteria » expression » LiteralExpression.java
/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2009 by Red Hat Inc and/or its affiliates or by
 * third-party contributors as indicated by either @author tags or express
 * copyright attribution statements applied by the authors.  All
 * third-party contributions are distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.ejb.criteria.expression;

import java.io.Serializable;
import javax.persistence.TypedQuery;

import org.hibernate.ejb.criteria.ValueHandlerFactory;
import org.hibernate.ejb.criteria.ParameterRegistry;
import org.hibernate.ejb.criteria.CriteriaBuilderImpl;
import org.hibernate.ejb.criteria.CriteriaQueryCompiler;

/**
 * Represents a literal expression.
 *
 * @author Steve Ebersole
 */
public class LiteralExpression<T> extends ExpressionImpl<T> implements Serializable {
  private Object literal;

  @SuppressWarnings({ "unchecked" })
  public LiteralExpression(CriteriaBuilderImpl criteriaBuilder, T literal) {
    this( criteriaBuilder, (Class<T>) determineClass( literal ), literal );
  }

  private static Class determineClass(Object literal) {
    return literal == null ? null : literal.getClass();
  }

  public LiteralExpression(CriteriaBuilderImpl criteriaBuilder, Class<T> type, T literal) {
    super( criteriaBuilder, type );
    this.literal = literal;
  }

  @SuppressWarnings({ "unchecked" })
  public T getLiteral() {
    return (T) literal;
  }

  public void registerParameters(ParameterRegistry registry) {
    // nothing to do
  }

  @SuppressWarnings({ "unchecked" })
  public String render(CriteriaQueryCompiler.RenderingContext renderingContext) {
    if ( ValueHandlerFactory.isNumeric( literal ) ) {
      return ValueHandlerFactory.determineAppropriateHandler( (Class) literal.getClass() ).render( literal );
    }

    // else...
    final String parameterName = renderingContext.generateParameterName();
    renderingContext.registerImplicitParameterBinding(
        new CriteriaQueryCompiler.ImplicitParameterBinding() {
          public String getParameterName() {
            return parameterName;
          }

          public Class getJavaType() {
            return LiteralExpression.this.getJavaType();
          }

          public void bind(TypedQuery typedQuery) {
            typedQuery.setParameter( parameterName, getLiteral() );
          }
        }
    );
    return ':' + parameterName;
  }

  @SuppressWarnings({ "unchecked" })
  public String renderProjection(CriteriaQueryCompiler.RenderingContext renderingContext) {
    // some drivers/servers do not like parameters in the select clause
    final ValueHandlerFactory.ValueHandler handler =
        ValueHandlerFactory.determineAppropriateHandler( literal.getClass() );
    if ( ValueHandlerFactory.isCharacter( literal ) ) {
      return '\'' + handler.render( literal ) + '\'';
    }
    else {
      return handler.render( literal );
    }
  }

  @Override
  @SuppressWarnings({ "unchecked" })
  protected void resetJavaType(Class targetType) {
    super.resetJavaType( targetType );
    ValueHandlerFactory.ValueHandler valueHandler = getValueHandler();
    if ( valueHandler == null ) {
      valueHandler = ValueHandlerFactory.determineAppropriateHandler( targetType );
      forceConversion( valueHandler );
    }

    if ( valueHandler != null ) {
      literal = valueHandler.convert( literal );
    }
  }
}
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