将HQL以及参数加载到Query实例中

最新推荐文章于 2025-01-21 11:05:54 发布

firecool2011

最新推荐文章于 2025-01-21 11:05:54 发布

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分类专栏： java 文章标签： Java Bean Hibernate DAO ORM

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本文介绍了一个自定义的 Hibernate DAO 类，通过反射机制实现了动态 SQL 的构造与执行，支持参数化查询，增强了应用的灵活性与复用性。

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package cn.com.oneslife.dao;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;

import org.hibernate.Query;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;

public class HibernateDAO extends HibernateDaoSupport {

    /**
     * @param hql
     * @param bean
     * @return
     * @throws SecurityException
     * @throws NoSuchMethodException
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     * @throws InvocationTargetException
     */
    public String getQuery(String hql, Object bean) throws SecurityException,
            NoSuchMethodException, IllegalArgumentException,
            IllegalAccessException, InvocationTargetException {

        Class<?> cl = bean.getClass();
        Field[] fields = cl.getDeclaredFields();

        Map<String, Object> listParam = new HashMap<String, Object>();
        String fieldName = null;
        String regex = "(and)?\\s+[a-zA-Z0-9]*\\.?[a-zA-Z0-9]*\\s+=\\s+:("
                + fieldName + ")";

        for (Field field : fields) {

            String methodName = "get"
                    + field.getName().substring(0, 1).toUpperCase();
            methodName += field.getName().substring(1);
            Method method = cl.getMethod(methodName);
            Object object = method.invoke(bean, new Object[] {});
            fieldName = field.getName();

            if (null == object) {
                hql = hql.replaceAll(regex, "");
            } else {
                listParam.put(field.getName(), object);
            }

        }

        hql = hql.replaceAll("where", "where true and");
        hql = hql.replaceAll("set\\s+and", "set");

        Query query = this.getSession().createQuery(hql);
        loadParam(query, listParam);

        return hql;
    }

    /**
     * @param hql
     * @param parameters
     * @return
     */
    public Query getQuery(String hql, Object... parameters) {

        Query query = this.getSession().createQuery(hql);

        for (int index = 0; index < parameters.length; index++) {
            query.setParameter(index + 1, parameters[index]);
        }

        return query;
    }

    /**
     * @param query
     * @param parameters
     * @return
     */
    private Query loadParam(Query query, Map<String, Object> parameters) {

        Set<Map.Entry<String, Object>> set = parameters.entrySet();
        Iterator<Entry<String, Object>> iter = set.iterator();

        while (iter.hasNext()) {

            Entry<String, Object> entry = iter.next();
            query.setParameter(entry.getKey(), entry.getValue());

        }

        return query;
    }
}