查询生成器

public class QueryBuilderVelocity implements QueryBuilder, ApplicationContextAware {

    /** logger */
    private static final Logger  logger = LoggerFactory.getLogger(QueryBuilderVelocity.class);

    /** Velocity引擎 */
    protected VelocityEngine     velocityEngine;

    /** Spring上下文 */
    protected ApplicationContext applicationContext;

    
    public String getQueryString(String queryName, Map<String, ?> conditions) {
        String queryTemplate = (String) this.applicationContext.getBean(queryName);

        if (queryTemplate == null) {
            throw new AppException(ErrorCode.ERROR_QUERY_TEMPLATE_NOT_EXIST, "查询模板不存在！");
        }

        try {
            Context context = new VelocityContext(conditions);
            StringWriter queryStringWriter = new StringWriter();
            this.velocityEngine.evaluate(context, queryStringWriter, "", queryTemplate);

            return queryStringWriter.toString();
        } catch (Exception ex) {
            logger.error("Velocity引擎生成查询语句出错！", ex);
            throw new AppException(ErrorCode.ERROR_BUILD_QUERY_STRING, "Velocity引擎生成查询语句出错！", ex);
        }
    }

    /**
     * 设置Velocity引擎
     * @param velocityEngine Velocity引擎
     */
    public void setVelocityEngine(VelocityEngine velocityEngine) {
        this.velocityEngine = velocityEngine;
    }

    /**
     * 设置Spring上下文
     * @param applicationContext Spring上下文
     */
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

}