Java Web Dao层设计

UML设计图

Dao层设计

实体类

package cn.zzuli.oa.domain;

public class Role {

}

package cn.zzuli.oa.domain;

public class User {

    private Long id;
    private String username;

    public User() {
        super();
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

}

BaseDao接口

package cn.zzuli.oa.base;

import java.util.List;

public interface BaseDao<T> {
    
    /**
     * 保存实体
     * @param entity
     */
    void save(T entity);
    
    /**
     * 删除实体
     * @param id
     */
    void delete(Long id);
    
    /**
     * 更新实体
     * @param entity
     */
    void update(T entity);
    
    /**
     * 
     * @param id
     * @return
     */
    T getById(Long id);
    
    /**
     * 查询实体
     * @param ids id的集合
     * @return
     */
    List<T> listByIds(Long[] ids);
    
    /**
     * 查询所有
     * @return
     */
    List<T> listAll();
    
}

BaseDaoImpl代码，实现BaseDao接口

package cn.zzuli.oa.base.impl;

import java.lang.reflect.ParameterizedType;
import java.util.Collections;
import java.util.List;

import javax.annotation.Resource;

import org.hibernate.Session;
import org.hibernate.SessionFactory;

import cn.zzuli.oa.base.BaseDao;

@SuppressWarnings("unchecked")
public abstract class BaseDaoImpl<T> implements BaseDao<T> {

    @Resource
    private SessionFactory sessionFactory;

    protected Class<T> clazz;
    
    public BaseDaoImpl() {
        //通过反射得到T的真实类型
        ParameterizedType pt = (ParameterizedType) this.getClass().getGenericSuperclass();//获取这个父类的泛型类型
        this.clazz = (Class<T>) pt.getActualTypeArguments()[0]; //获取第一个泛型T的类型
        
        System.out.println("clazz = " + clazz.getName());
    }
    

    @Override
    public void save(T entity) {
        getSession().save(entity);
    }

    @Override
    public void delete(Long id) {
        Object obj = getSession().get(clazz, id);
        getSession().delete(obj);
    }

    @Override
    public void update(T entity) {
        getSession().update(entity);
    }

    @Override
    public T getById(Long id) {
        return (T) getSession().get(clazz, id);
    }

    @Override
    public List<T> listByIds(Long[] ids) {
        if (ids == null || ids.length == 0) {
            return Collections.EMPTY_LIST;
        }
        return getSession().createQuery("FROM " + clazz.getSimpleName() + " WHERE id IN(:ids)")
                .setParameterList("ids", ids).list();
    }

    @Override
    public List<T> listAll() {
        return getSession().createQuery("FROM " + clazz.getSimpleName()).list();
    }

    /**
     * 获取当前可用的Session
     * 
     * @return 当前可用的Session
     */
    protected Session getSession() {
        return sessionFactory.getCurrentSession();
    }

}

RoleDao接口，继承BaseDao

package cn.zzuli.oa.dao;

import cn.zzuli.oa.base.BaseDao;
import cn.zzuli.oa.domain.Role;

public interface RoleDao extends BaseDao<Role> {

}

UserDao接口，继承BaseDao

UserDao实现类UserDaoImpl可以实现的自己的功能代码

package cn.zzuli.oa.dao;

import cn.zzuli.oa.base.BaseDao;
import cn.zzuli.oa.domain.User;

public interface UserDao extends BaseDao<User>{
    
}

RoleDaoImpl代码，继承BaseDaoImpl，实现RoleDao

package cn.zzuli.oa.dao.impl;

import org.springframework.stereotype.Repository;

import cn.zzuli.oa.base.impl.BaseDaoImpl;
import cn.zzuli.oa.dao.RoleDao;
import cn.zzuli.oa.domain.Role;

@Repository
public class RoleDaoImpl extends BaseDaoImpl<Role> implements RoleDao {

}

UserDaoImpl代码，继承BaseDaoImpl，实现UserDao

package cn.zzuli.oa.dao.impl;

import org.springframework.stereotype.Repository;

import cn.zzuli.oa.base.impl.BaseDaoImpl;
import cn.zzuli.oa.dao.UserDao;
import cn.zzuli.oa.domain.User;

@Repository
public class UserDaoImpl extends BaseDaoImpl<User> implements UserDao{

}

测试类

package cn.zzuli.oa.base;

import org.junit.Test;

import cn.zzuli.oa.dao.RoleDao;
import cn.zzuli.oa.dao.UserDao;
import cn.zzuli.oa.dao.impl.RoleDaoImpl;
import cn.zzuli.oa.dao.impl.UserDaoImpl;
import cn.zzuli.oa.domain.Role;
import cn.zzuli.oa.domain.User;

public class BaseDaoTest {

    @Test
    public void testGetById() {
        UserDao userDao = new UserDaoImpl();
        RoleDao roleDao = new RoleDaoImpl();
        
    }

}

实现效果

实现效果

此处输出的正是BaseDao实现类BaseDaoImple中构造方法获取的泛型的类型，