dao层的泛型实现(2种方法)

一：

package com.wzs.test2.dao;

import java.util.List;

public interface CommonDAO {
	public <T> void sava(T entity); // 保存用户，无返回值；

	public <T> void remove(T entity); // 删除用户

	public <T> void update(T entity); // 更新用户

	public <T> T findById(Class<T> entityClass, Integer id); // 通过id来查找某一个用户；

	public <T> List<T> findAll(Class<T> entityclass); // 使用范型List<>。查询全部的用户信息

}

package com.wzs.test2.dao.impl;

import java.util.List;

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

import com.wzs.test2.dao.CommonDAO;

public class CommonDAOImpl extends HibernateDaoSupport implements CommonDAO {
	@SuppressWarnings("unchecked")
	public <T> List<T> findAll(Class<T> entityclass) {
		String hql = "from " + entityclass.getName() + " as a order by a.id desc";
		return this.getHibernateTemplate().find(hql);
	}

	@SuppressWarnings("unchecked")
	public <T> T findById(Class<T> entityClass, Integer id) {
		return (T) this.getHibernateTemplate().get(entityClass, id);
	}

	public <T> void remove(T entity) {
		this.getHibernateTemplate().delete(entity);
	}

	public <T> void sava(T entity) {
		this.getHibernateTemplate().save(entity);
	}

	public <T> void update(T entity) {
		this.getHibernateTemplate().update(entity);
	}

}

二：

package com.wzs.test.dao;

import java.io.Serializable;
import java.util.Collection;

public interface BaseDao<T> {
	public void saveEntity(T t);

	public Collection<T> get();

	public void updateEntity(T t);

	public void deleteEntity(Serializable id);

	public T getEntityById(Serializable id);

}

package com.wzs.test.dao.impl;

import java.io.Serializable;
import java.lang.reflect.ParameterizedType;
import java.util.Collection;

import org.springframework.orm.hibernate3.HibernateTemplate;

import com.wzs.test.dao.BaseDao;

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

	private HibernateTemplate hibernateTemplate;

	private Class classt;

	public BaseDaoImpl() {
		// ParameterizedType就是泛型，关键部分
		ParameterizedType type = (ParameterizedType) this.getClass().getGenericSuperclass();
		this.classt = (Class) type.getActualTypeArguments()[0];// <T>
		System.out.println(type.getRawType());
	}

	public void deleteEntity(Serializable id) {
		T t = this.getEntityById(id);
		hibernateTemplate.delete(t);

	}

	public Collection<T> get() {
		System.out.println(classt.getSimpleName());
		return this.hibernateTemplate.find("from " + classt.getSimpleName());
	}

	public T getEntityById(Serializable id) {
		return (T) this.hibernateTemplate.get(classt, id);
	}

	public void saveEntity(T t) {
		this.hibernateTemplate.save(t);

	}

	public void updateEntity(T t) {
		this.hibernateTemplate.update(t);
	}

	// set&&get
	public HibernateTemplate getHibernateTemplate() {
		return hibernateTemplate;
	}

	public void setHibernateTemplate(HibernateTemplate hibernateTemplate) {
		this.hibernateTemplate = hibernateTemplate;
	}

}

package com.wzs.test.dao;

public interface StudentDao<Student> extends BaseDao<Student> {

}

package com.wzs.test.dao.impl;

import org.springframework.stereotype.Component;

import com.wzs.test.dao.StudentDao;
import com.wzs.test.dao.bean.Student;

@Component
public class StudentDaoImpl extends BaseDaoImpl<Student> implements StudentDao<Student> {

}

package com.wzs.test.dao.bean;

public class Student {

}

參考：

http://www.cnblogs.com/shenliang123/archive/2012/04/05/2433134.html

http://blog.****.net/qiaoge134/article/details/20228139