mybaits开发之通用 dao层编写

来源：互联网发布：geekbench mac下载编辑：程序博客网时间：2024/05/20 15:37

在springMVC+mybatis框架开发时，通常我们会写多的dao,如userDao,roleDao,departDao等等，这样开发效果就很慢，不是很好，所以编写个通用dao.

1.编写dao接口

public interface DAO {/** * 保存对象 * @param str * @param obj * @return * @throws Exception */public Object save(String str, Object obj) throws Exception;/** * 修改对象 * @param str * @param obj * @return * @throws Exception */public Object update(String str, Object obj) throws Exception;/** * 删除对象  * @param str * @param obj * @return * @throws Exception */public Object delete(String str, Object obj) throws Exception;/** * 查找对象 * @param str * @param obj * @return * @throws Exception */public Object findForObject(String str, Object obj) throws Exception;/** * 查找对象 * @param str * @param obj * @return * @throws Exception */public Object findForList(String str, Object obj) throws Exception;/** * 查找对象封装成Map * @param s * @param obj * @return * @throws Exception */public Object findForMap(String sql, Object obj, String key , String value) throws Exception;}

2.编写dao 实现类

public class DaoSupport implements DAO {@Resource(name = "sqlSessionTemplate")private SqlSessionTemplate sqlSessionTemplate;/** * 保存对象 * @param str * @param obj * @return * @throws Exception */public Object save(String str, Object obj) throws Exception {return sqlSessionTemplate.insert(str, obj);}/** * 批量更新 * @param str * @param obj * @return * @throws Exception */public Object batchSave(String str, List objs )throws Exception{return sqlSessionTemplate.insert(str, objs);}/** * 修改对象 * @param str * @param obj * @return * @throws Exception */public Object update(String str, Object obj) throws Exception {return sqlSessionTemplate.update(str, obj);}/** * 批量更新 * @param str * @param obj * @return * @throws Exception */public void batchUpdate(String str, List objs )throws Exception{SqlSessionFactory sqlSessionFactory = sqlSessionTemplate.getSqlSessionFactory();//批量执行器SqlSession sqlSession = sqlSessionFactory.openSession(ExecutorType.BATCH,false);try{if(objs!=null){for(int i=0,size=objs.size();i<size;i++){sqlSession.update(str, objs.get(i));}sqlSession.flushStatements();sqlSession.commit();sqlSession.clearCache();}}finally{sqlSession.close();}}/** * 批量更新 * @param str * @param obj * @return * @throws Exception */public Object batchDelete(String str, List objs )throws Exception{return sqlSessionTemplate.delete(str, objs);}/** * 删除对象  * @param str * @param obj * @return * @throws Exception */public Object delete(String str, Object obj) throws Exception {return sqlSessionTemplate.delete(str, obj);} /** * 查找对象 * @param str * @param obj * @return * @throws Exception */public Object findForObject(String str, Object obj) throws Exception {return sqlSessionTemplate.selectOne(str, obj);}/** * 查找对象 * @param str * @param obj * @return * @throws Exception */public Object findForList(String str, Object obj) throws Exception {return sqlSessionTemplate.selectList(str, obj);}public Object findForMap(String str, Object obj, String key, String value) throws Exception {return sqlSessionTemplate.selectMap(str, obj, key);}}

3.那么怎么使用呢？

public class UserService {@Resource(name = "daoSupport")private DaoSupport dao;/**通过id获取数据*/public User getUserAndRoleById(String userid) throws Exception {return (User) dao.findForObject("UserMapper.getUserAndRoleById", <span style="font-family: Arial, Helvetica, sans-serif;">userid</span>);}}

4. UserMapper.xml中的配置

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="UserMapper">

<select id="getUserById" parameterType="String" resultType="User">select  * from SYS_USER where userId=#{userId}</select></mapper>

好了，就这样，是不是觉得很简单，直接释放出dao层，一个通用dao.

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