BaseDao的编写：实现 增，删，改，查，分页这些公共方法的编写

1.BaseDao接口

package com.learning.crm.base;

import java.io.Serializable;
import java.util.List;

public interface BaseDao<T> {

    /**
     * 保存
     * @param t
     */
    public void save(T t);

    /**
     * 更新
     * @param t
     */
    public void update(T t);

    /**
     * 查询所有
     * @return
     */
    public List<T> findAll();

    /**
     * 根据id查询
     * @param id
     * @return
     */
    public T findById(Serializable id);

    /**
     * 删除
     * @param t
     */
    public void delete(T t);

    /**
     * 条件加分页查询
     * @param t
     * @param pageSize
     * @param currentPage
     * @return
     */
    List<T> findAll(final String condition,final Object[] objects, final int pageSize, final int currentPage);
}

2.BaseDaoImpl:

package com.learning.crm.base.impl;

import java.io.Serializable;
import java.lang.reflect.ParameterizedType;
import java.sql.SQLException;
import java.util.List;

import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;
import org.springframework.orm.hibernate3.HibernateCallback;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;

import com.learning.crm.base.BaseDao;

public class BaseDaoImpl<T> extends HibernateDaoSupport implements BaseDao<T>{

    private Class<?> clazz;

    public BaseDaoImpl() throws InstantiationException, IllegalAccessException {
        //获得T
        ParameterizedType parameterizedType= (ParameterizedType) this.getClass().getGenericSuperclass();
        //获得运行时的T类型
        clazz = (Class<?>) parameterizedType.getActualTypeArguments()[0];

    }

    @Override
    public List<T> findAll(String condition,final Object[] objects, final int pageSize, final int currentPage) {

        final String hql="from "+clazz.getName()+" where 1=1 "+condition;
        return this.getHibernateTemplate().execute(new HibernateCallback<List<T>>() {

            public List<T> doInHibernate(Session session) throws HibernateException, SQLException {
                    Query query = session.createQuery(hql);
                    for (int i = 0; i < objects.length; i++) {
                        query.setParameter(i, objects[i]);
                    }
                    query.setFirstResult((currentPage-1)*pageSize);
                    query.setMaxResults(pageSize);
                return query.list();
            }
        });
    }

    @Override
    public void save(T t) {
        this.getHibernateTemplate().save(t);

    }

    @Override
    public void update(T t) {

        this.getHibernateTemplate().update(t);
    }

    @Override
    public List<T> findAll() {

        return this.getHibernateTemplate().find(" from "+ clazz.getName());
    }

    @Override
    public T findById(Serializable id) {
        this.getHibernateTemplate().get(clazz, id);
        return null;
    }

    @Override
    public void delete(T t) {
        this.getHibernateTemplate().delete(t);

    }

}

3.编写自己的Dao时，比如UserDao要继承BaseDao，UserDaoImpl要实现UserDao，继承BaseDaoImpl