mybatis大框架
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MyBatis 开源的数据持久化层框架
实体类与SQL语句之间建立映射关系
一：MyBatis前身是IBatis,本是Apache的一个开源的项目，
基于SQL语法，简单易学 ，是耦合度降低，方便程序调式
二：搭建Mybatis的开发步骤:
a:下载mybatis-3.3.3.jar包并导入工程
b.编写MyBatis核心配置文件（configuration.xml）
c.创建实体类-POJO
d.DAO层-SQL映射文件（mapper.xml）
e.创建测试类
读取全局配置文件mybatis-config.xml
创建SqlSessionFactory对象，读取配置文件
创建SqlSession对象
调用mapper文件进行数据操作
我的大配置（全局配置里）
<configuration> <properties resource="database.properties"/> <environments default="development"> <settings> <setting name="LogImpl" value="LOG4J"> </setting> </settings> <environment id="development"> <transactionManager type="JDBC"></transactionManager> <dataSource type="POOLED"> <property name="driver" value="${driver}"></property> <property name="url" value="${url}"></property> <property name="username" value="${user}"></property> <property name="userpwd" value="${password}"></property> </dataSource> </environment> </environments>
<mappers>
<mapper resource="cn/smbms/dao/user/UserMapper" </mappers> </properties> </configuration>
小配置：
在dao层：
<mapper namespace="cn.smbms.dao.user.UserMapper"> <!--查询用户表的记录数--> <select id="count" resultType="int"> select count(1) as count from login </select> </mapper>
在userMapperTest: public class UserMapperTest{ private Logger logger=Logger.getLogger(UserMapperTest.class); @Test public void test(){ string resource="mybatis-config.xml" int count=0; SqlSession sqlsession=null; try{ //1.获取mybatis-config.xml输入流 Inputstream is=Resources.getResourceAsStream(resource) //2.创建SqlSessionFactory对象，完成对配置文件的读取 SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(is). //3.创建SqlSession sqlSession=factory.openSession(); //4.调用mapper文件来对数据文件进行操作,必须将mapper文件引入到 count=sqlSession.selectOne("cn.smbms.dao.user.UserMapp"); logger.debug("UserMapper"+count); }catch(IoException e){ e.printStackTrace(); }finally{ sqlSession.close(); }
优缺点：
优点：
与JDBC相比，减少了50%以上的代码量
小巧易学
提供XML标签，支持编写动态SQL
提供映射标签
缺点：
数据库移植性差
编写工作量大
MyBatis专注于SQL本身，是一个足够灵活得DAO层解决方案
适用于性能要求较高或者需求多变的互联网项目
四：：：：：基本要素：：：：：
三个基本要素：
1. 核心接口和类：
SqlSessionFactoryBuilder
SqlSessionFactory
SqlSession
2. mybatis-config.xml
3.mapper.xml SQL映射文件
共用的Util工具类
MyBatisUtil:
public class MyBatisUtil{ private static SqlSessionFactory factory; static{ try{ InputStream is=Resources.getResourceAsStream(""); factory=new SqlSessionFactoryBuilder().bulid(is); }catch（IOException e）{ e.printStackTrace(); } } public static SqlSession createSqlSession(){ return factory.openSession(false); } public static void closeSqlSession(SqlSession sql){ if(null!=sqlSession){ sqlSession.close(); } } }
核心配置文件：
environments元素：
1.表示MyBatis的多套运行环境，将SQL映射到多个不同的数据上。
2.子元素节点：environment，但是必须指定其中一个默认运行环境（通过default指定）
transactionManager-事物管理器
<transactionManager type="[JDBC|MANAGED]"/> ======>>MANAGED(托管)
3.dataSource元素使用基本的JDBC数据源接口来配置JDBC连接对象的资源
三种内建的数据源类型：
<dataSource type="[UNPOOLED|POOLED|JNDI]"/>
复杂对象：map
所有对象 === 增删改查 ===一级缓存二级缓存
public interface StudentDao { //查询所有信息 public List<Student> selectStudent() throws Exception; //主键id查询 public Student getById(int ID); //添加学生 public int addStudent(Student stu) throws Exception; //修改学生 public int upStudent(Student stu) throws Exception; //删除学生 public int delStudent(int ID) throws Exception; //模糊条件查询：学生姓名是豆，并且年龄在10岁以上的 public List<Student> ConditionStudent(Student stu) throws Exception; //findStudent<map>集合 多条件查询1 public List<Student> findStudent(Map<String,Object> map); //按照索引号查询 多条件查询2 public List<Student> ConditionParameters(String StuName,int StuAge) ; //智能标签if 检测用户是否录入学生姓名和年龄 public List<Student> findByIf(Student stu) throws Exception; //智能标签choose 检测用户是否录入学生姓名和年龄 public List<Student> findByChoose(Student stu) throws Exception; //智能标签foreach 检测In(或者) public List<Student> findByForeach(int[] arg) throws Exception; //智能标签foreach List<Integer> 检测In(或者) public List<Student> ForeachList(List<Integer> list) throws Exception; //智能标签foreach List<Student> 检测In(或者) public List<Student> ForeachListStudent(List<Student> list) throws Exception; //if-set public int getset(Student stu); //01.查询指定老师教的学生 多对多 public RTeacher getStudentByTid(int id); //根据父分类编号，检索该父类编号对应的所有子分类的集合==============递归方法 public List<Category> getChildrenByPid(int pid); }
小配置文件里：
<mapper namespace="cn.zixin.dao.StudentDao"> <!--二级缓存第二步--> <cache/> <!--SQL片段--> <sql id="columns"> ID,StuName,StuAge,StuTime </sql> <!--查询所有的resultMap的用法：--> <resultMap id="studentmap" type="Student"> <id column="ID" property="ID"></id> </resultMap> <select id="selectStudentS" resultMap="studentmap"> select <include refid="columns"></include> from student </select> <!--查询所有--> <select id="selectStudent" resultType="Student"> select * from student </select> <!--通过id查询--> <select id="getById" resultType="Student"> select * from student where ID=#{ID} </select> <!--添加学生--> <insert id="addStudent"> INSERT INTO student(StuName,StuAge,StuTime) VALUE (#{StuName},#{StuAge},#{StuTime}) </insert> <!--修改学生--> <update id="upStudent"> UPDATE student SET StuName=#{StuName} WHERE ID=#{ID} </update> <!--删除学生--> <delete id="delStudent"> DELETE from student where ID=#{ID} </delete> <!--模糊查询学生--> <!--SELECT * from student WHERE StuName like concat(\'%\',#{StuName},\'%\') AND StuAge>#{StuAge}--> <!--可以被SQL注入到 SELECT * from student WHERE StuName like \'%${StuName}%\' AND StuAge>#{StuAge}--> <select id="ConditionStudent" resultType="Student"> SELECT * from student WHERE StuName like \'%\' #{StuName} \'%\' AND StuAge>#{StuAge} </select> <!-- MAP集合查询 多条件查询--> <select id="findStudent" resultType="Student"> select * from student where StuName like \'%\' #{StuName} \'%\' AND StuAge>#{StuAge} </select> <!-- <resultMap id="Student" type="Student"> <id property="id" column="id"></id> <result column="StuName" property="StuName"></result> <result property="StuAge" column="StuAge"></result> </resultMap> --> <!--根据索引查询--> <select id="ConditionParameters" resultType="Student"> SELECT * FROM student WHERE StuName like \'%\' #{0} \'%\' and StuAge >#{1} </select> <!--智能标签if 检测用户是否录入学生姓名和年龄--> <select id="findByIf" resultType="Student"> SELECT * FROM student <where> <if test="StuName!=null"> <!--用户录入的姓名字段--> AND StuName LIKE \'%\'#{StuName}\'%\' </if> <if test="StuAge!=null"> AND StuAge>#{StuAge} </if> </where> </select> <!--智能标签Choose 检测用户是否录入学生姓名和年龄--> <select id="findByChoose" resultType="Student"> SELECT * FROM student <where> <choose> <when test="StuName!=null"> AND StuName LIKE \'%\'#{StuName}\'%\' </when> <when test="StuAge!=null"> AND StuAge>#{StuAge} </when> <otherwise> AND 1=2 </otherwise> </choose> </where> </select> <!--智能标签Foreach Array 检测In(或者)--> <select id="findByForeach" resultType="Student"> SELECT * FROM student <where> <if test="array.length>0"> ID IN <foreach collection="array" open="(" close=")" separator="," item="aD"> #{aD} </foreach> </if> </where> </select> <!--智能标签Foreach List<Integer> 检测In(或者)--> <select id="ForeachList" resultType="Student"> SELECT * FROM student <where> <if test="list.size>0"> ID IN <foreach collection="list" open="(" close=")" separator="," item="ID"> #{ID} </foreach> </if> </where> </select> <!--智能标签Foreach List<student> 检测In(或者)--> <select id="ForeachListStudent" resultType="Student"> SELECT * FROM student <where> <if test="list.size>0"> ID IN <foreach collection="list" open="(" close=")" separator="," item="stu"> #{stu.ID} </foreach> </if> </where> </select> <!--if-set--> <update id="getset" > UPDATE student <set> <if test="StuName!=null" >StuName=#{StuName},</if> <if test="StuAge!=null">StuAge=#{StuAge},</if> </set> WHERE ID=#{ID} </update> <!--查询指定老师教的学生 多对多--> <resultMap id="stuMapper" type="RTeacher"> <id column="tid" property="tid"></id> <result column="tname" property="tname"></result> <collection property="stus" ofType="RStudent"> <id column="sid" property="sid"></id> <result column="sname" property="sname"></result> </collection> </resultMap> <select id="getStudentByTid" resultMap="stuMapper" parameterType="RTeacher"> SELECT sname,sid,tid,tname FROM student2,teacher,teacher_student WHERE student2.sid=teacher_student.studentid AND teacher.tid=teacher_student.teacherid AND tid=#{tid} </select>
测试类里：
//查询 @Test public void findsStudent() { List<Student> list = myBatis.getSession().selectList("selectStudentS"); for (Student item : list) { System.out.println(item.getStuName()); } } //id查询 @Test public void getById() { /* //映射关系第一种Class<T>类型 Class<StudentText> aClass = StudentText.class; //映射关系第二种 try { Class<StudentText> name = ( Class<StudentText>)Class.forName("cn.zixin.test.StudentText"); } catch (ClassNotFoundException e) { e.printStackTrace(); }*/ //映射关系第三种 getMapper SqlSession session = myBatis.getSession(); StudentDao dao = session.getMapper(StudentDao.class); Student byId = dao.getById(1); System.out.println(byId.getStuName()); //Student stu= session.selectOne("getById",1); // System.out.println(stu.getStuName()); session.commit(); session.close(); } //增加 @Test public void addStudent() throws Exception { SqlSession session = myBatis.getSession(); StudentDao dao = session.getMapper(StudentDao.class); Student stu = new Student(); stu.setStuName("豆豆"); stu.setStuAge(29); stu.setStuTime(new Date()); dao.addStudent(stu); session.commit(); //增删改 手动提交事务 System.out.println("ok"); session.close(); } //修改 @Test public void upStudent() throws Exception { SqlSession session = myBatis.getSession(); StudentDao dao = session.getMapper(StudentDao.class); Student stu = new Student(); stu.setStuName("豆豆"); stu.setID(2); dao.upStudent(stu); session.commit(); //增删改 手动提交事务 System.out.println("ok"); session.close(); } //删除 @Test public void delStudent() throws Exception { SqlSession session = myBatis.getSession(); StudentDao dao = session.getMapper(StudentDao.class); dao.delStudent(2); session.commit(); //增删改 手动提交事务 System.out.println("ok"); session.close(); } //模糊查询 @Test public void ConditionStudent() throws Exception { SqlSession session = myBatis.getSession(); StudentDao dao = session.getMapper(StudentDao.class); Student stu = new Student(); stu.setStuName("豆"); stu.setStuAge(30); List<Student> list = dao.ConditionStudent(stu); for (Student item : list) { System.out.println(item.getStuName()); } session.commit(); //增删改 手动提交事务 System.out.println("ok"); session.close(); } //findStudent<map>集合 多条件查询 @Test public void mapsStudent() throws Exception { SqlSession session = myBatis.getSession(); StudentDao dao = session.getMapper(StudentDao.class); Map<String,Object> map=new HashMap<String,Object>(); map.put("StuName","豆"); map.put("StuAge",20); List<Student> list = dao.findStudent(map); for (Student item : list) { System.out.println(item.getStuName()); } System.out.println("ok"); session.close(); } //按照索引号查询 @Test public void ConditionParameter() { String StuName = "豆"; int StuAge = 20; List<Student> list = myBatis.getSession().getMapper(StudentDao.class).ConditionParameters(StuName,StuAge); for (Student stu : list) { System.out.println(stu.getStuName()); } } @Test //智能标签if public void findByIf() throws Exception { Student stu = new Student(); stu.setStuName( "豆"); stu.setStuAge( 29); List<Student> list = myBatis.getSession().getMapper(StudentDao.class).findByIf(stu); for (Student item : list) { System.out.println(item.getStuName()); } System.out.println("ok"); } @Test //智能标签choose public void findBychoose() throws Exception { Student stu = new Student(); stu.setStuName( "豆"); stu.setStuAge( 29); List<Student> list = myBatis.getSession().getMapper(StudentDao.class).findByChoose(stu); for (Student item : list) { System.out.println(item.getStuName()); } System.out.println("ok"); } @Test //智能标签foreach array public void findByForeach() throws Exception { int[] arg={2,5}; List<Student> list = myBatis.getSession().getMapper(StudentDao.class).findByForeach(arg); for (Student item : list) { System.out.println(item.getStuName()); } System.out.println("ok"); } @Test //智能标签foreach List<Integer> public void foreachList() throws Exception { List<Integer> lists=new ArrayList<Integer>(); lists.add(2); lists.add(5); List<Student> list = myBatis.getSession().getMapper(StudentDao.class).ForeachList(lists); for (Student item : list) { System.out.println(item.getStuName()); } System.out.println("ok"); } @Test //智能标签foreach List<Student> public void foreachListStudent() throws Exception { List<Student> lists=new ArrayList<Student>(); Student s1=new Student(); s1.setID(2); Student s2=new Student(); s2.setID(5); lists.add(s1); lists.add(s2); List<Student> list = myBatis.getSession().getMapper(StudentDao.class).ForeachListStudent(lists); for (Student item : list) { System.out.println(item.getStuName()); } System.out.println("ok"); } @Test // 多表联查 一对多 单条SQL public void selectOne() throws Exception { Dept dept = myBatis.getSession().getMapper(IdeptDao.class).getEmpsByDeptNO(1); System.out.println(dept.getDeptname()); for (Emp emp:dept.getEmps()){ System.out.println(emp.getEmpname()); } System.out.println("ok"); } @Test // 多表联查 一对多 多条SQL public void selectmoen() throws Exception { Dept dept = myBatis.getSession().getMapper(IdeptDao.class).getEmpsByDeptNoMutilSQL(1); System.out.println(dept.getDeptname()); for (Emp emp:dept.getEmps()){ System.out.println(emp.getEmpname()); } System.out.println("ok"); } @Test // 多对一 根据员工的编号，获取员工姓名 和 部门名称 单条SQL public void selectManyToOne() throws Exception { Emp emp = myBatis.getSession().getMapper(IdeptDao.class).getEmpByEmpNo(1); System.out.println(emp.getEmpname()); System.out.println(emp.getDept().getDeptname()); System.out.println("ok"); } @Test // 多对一 根据员工的编号，获取员工姓名 和 部门名称 多条SQL public void selectMany() throws Exception { Emp emp = myBatis.getSession().getMapper(IdeptDao.class).getEmpByEmpNoMutilSQL(1); System.out.println(emp.getEmpname()); System.out.println(emp.getDept().getDeptname()); System.out.println("ok"); } @Test //if-set public void testIsSet() throws Exception { Student stu=new Student(); stu.setStuName("欣欣"); stu.setStuAge(10); stu.setID(1); int i = myBatis.getSession().getMapper(StudentDao.class).getset(stu); System.out.println(i); } @Test //多对多 查询指定老师教的学生 public void testManyToMany() throws Exception { RTeacher teacher = myBatis.getSession().getMapper(StudentDao.class).getStudentByTid(1); System.out.println(teacher.getTname()); for (RStudent stu:teacher.getStus()){ System.out.println(stu.getSname()); } System.out.println("ok"); } @Test //自连接测试=======递归 public void testSelf() throws Exception { List<Category> list= myBatis.getSession().getMapper(StudentDao.以上是关于mybatis大框架的主要内容，如果未能解决你的问题，请参考以下文章