mybatis 入门搭建

首先导包依赖如下 <dependencies> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.15</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.1</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.11</version> <scope>test</scope> </dependency> </dependencies>构建SqlSessionFactoryMyBatis应用是以SqlSessionFactory为中心的,实例可以通过SqlSessionFactoryBuilder获得.其中SqlSessionFactory是工厂接口,任务用于创建SqlSession 配置文件将会解析配置XML文件在Configuration类对象中.配置XML获取数据源,事务管理器,映射器在resource文件下新建mybatis-config.xml文件配置文件内容如下<?xml version=“1.0” encoding=“UTF-8” ?><!DOCTYPE configuration PUBLIC “-//mybatis.org//DTD Config 3.0//EN” “http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration> <!– 定义别名 –> <typeAliases> <typeAlias type=“com.ming.Role” alias=“role”/> </typeAliases> <!– 定义数据库信息 –> <environments default=“development”> <environment id=“development”> <!– jdbc事物管理 –> <transactionManager type=“JDBC”></transactionManager> <!– 数据库链接信息 –> <dataSource type=“POOLED”> <property name=“driver” value=“com.mysql.cj.jdbc.Driver”/> <property name=“url” value=“jdbc:mysql://47.94.95.84:32786/mybatis”/> <property name=“username” value=“mybatis”/> <property name=“password” value=“ABCcba20170607”/> </dataSource> </environment> </environments></configuration>新建类package com.ming;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import java.io.IOException;import java.io.InputStream;public class Role { public String getSqlSessionFactory(){ String resource = “mybatis-config.xml”; try {// 获得输入流 InputStream inputStream; inputStream = Resources.getResourceAsStream(resource); // 获得SqlSessionFactory工厂 SqlSessionFactory sqlSessionFactory = null; sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); }catch (IOException e){ e.printStackTrace(); } return null; }}最后新建测试类package com.ming;import org.junit.After;import org.junit.Before;import org.junit.Test;public class RoleTest { private Role role = null; @Before public void setUp() throws Exception { this.role = new Role(); } @After public void tearDown() throws Exception { } @Test public void getSqlSessionFactory() { role.getSqlSessionFactory(); }}此时的目录结构代码方式构建 public SqlSessionFactory getSqlSessionFactory1(){ // 创建数据库连接池 PooledDataSource dataSource = new PooledDataSource(); dataSource.setDriver(“com.mysql.cj.jdbc.Driver”); dataSource.setUrl(“jdbc:mysql://47.94.95.84:32786/mybatis”); dataSource.setUsername(“mybatis”); dataSource.setPassword(“ABCcba20170607”); // 构建数据库事物 TransactionFactory transactionFactory = new JdbcTransactionFactory(); // 创建数据库环境 Environment environment = new Environment(“development”, transactionFactory, dataSource); // 构建Configuration对象 Configuration configuration = new Configuration(environment); // 注册上下文别名 configuration.getTypeAliasRegistry().registerAlias(“role”, Role.class); // 创建映射器 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration); return sqlSessionFactory; }书写测试用例如下package com.ming;import org.junit.After;import org.junit.Before;import org.junit.Test;public class RoleTest { private Role role = null; @Before public void setUp() throws Exception { this.role = new Role(); } @After public void tearDown() throws Exception { } @Test public void getSqlSessionFactory() { role.getSqlSessionFactory(); } @Test public void getSqlSessionFactory1() { role.getSqlSessionFactory1(); }}创建SqlSessionSqlSession属于门面,通过SqlSession可以获得需要的什么信息 SqlSession sqlSession = null; try{ // 创建一个sqlsession会话 sqlSession = sqlSessionFactory.openSession(); sqlSession.commit(); }catch (Exception e){ // 输出错误信息 System.out.println(e.getMessage()); // 进行事物操作,回滚数据库数据 sqlSession.rollback(); }finally { // 进行资源关闭 if(sqlSession != null){ sqlSession.close(); } }SqlSession作用,获取映射器,通过命名信息执行sql结果映射器映射器由java和xml文件共同组成,作用定义参数类型描述缓存描述sql定义查询结果和POJO映射关系先给出java接口package com.ming;public interface RoleMapper { public Role getRole(Long id);}根据给定的id获取角色对象给出映射文件,然后在生成的时候会根据接口实现类,生成对象.先编写POJOpackage com.ming;// POJOpublic class Role { private int id; private String roleName; private String note; public void setId(int id) { this.id = id; } public void setRoleName(String roleName) { this.roleName = roleName; } public void setNote(String note) { this.note = note; } public int getId() { return id; } public String getRoleName() { return roleName; } public String getNote() { return note; }}在编写映射配置文件<?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"><!-- 定义接口类 –><mapper namespace=“com.ming.RoleMapper”> <!– 定义的接口方法为getRole 类型参数为long 返回的结果为role 即之前定义在xml文件中定义的vo别名 –> <select id=“getRole” parameterType=“int” resultType=“role”> <!– 定义sql语句–> SELECT id, role_name as roleName, note FROM t_role WHERE id = #{id} </select></mapper>最后编写mybatis,添加映射器配置文件<?xml version=“1.0” encoding=“UTF-8” ?><!DOCTYPE configuration PUBLIC “-//mybatis.org//DTD Config 3.0//EN” “http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration> <!– 定义别名 –> <typeAliases> <typeAlias type=“com.ming.Role” alias=“role”/> </typeAliases> <!– 定义数据库信息 –> <environments default=“development”> <environment id=“development”> <!– jdbc事物管理 –> <transactionManager type=“JDBC”></transactionManager> <!– 数据库链接信息 –> <dataSource type=“POOLED”> <property name=“driver” value=“com.mysql.cj.jdbc.Driver”/> <property name=“url” value=“jdbc:mysql://47.94.95.84:32786/mybatis”/> <property name=“username” value=“mybatis”/> <property name=“password” value=“ABCcba20170607”/> </dataSource> </environment> </environments> <!– 定义映射器 –> <mappers> <mapper resource=“RoleMapper.xml”></mapper> </mappers></configuration>最后再编写执行sql的类package com.ming;import org.apache.ibatis.datasource.pooled.PooledDataSource;import org.apache.ibatis.io.Resources;import org.apache.ibatis.mapping.Environment;import org.apache.ibatis.session.Configuration;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import org.apache.ibatis.transaction.TransactionFactory;import org.apache.ibatis.transaction.jdbc.JdbcTransactionFactory;import java.io.IOException;import java.io.InputStream;public class MyBatis { public String getSqlSessionFactory(){ String resource = “mybatis-config.xml”; SqlSessionFactory sqlSessionFactory = null; try {// 获得输入流 InputStream inputStream; inputStream = Resources.getResourceAsStream(resource); // 获得SqlSessionFactory工厂 sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); }catch (IOException e){ e.printStackTrace(); } SqlSession sqlSession = null; try{ // 创建一个sqlsession会话 sqlSession = sqlSessionFactory.openSession(); // 获得映射器 // 接口传入映射器中 RoleMapper roleMapper = sqlSession.getMapper(RoleMapper.class); // 执行方法 Role role = roleMapper.getRole(0); System.out.println(role.getRoleName()); // 刷新语句并提交链接 sqlSession.commit(); }catch (Exception e){ // 输出错误信息 System.out.println(e.getMessage()); // 进行事物操作,回滚数据库数据 sqlSession.rollback(); }finally { // 进行资源关闭 if(sqlSession != null){ sqlSession.close(); } } return null; } public SqlSessionFactory getSqlSessionFactory1(){ // 创建数据库连接池 PooledDataSource dataSource = new PooledDataSource(); dataSource.setDriver(“com.mysql.cj.jdbc.Driver”); dataSource.setUrl(“jdbc:mysql://47.94.95.84:32786/mybatis”); dataSource.setUsername(“mybatis”); dataSource.setPassword(“ABCcba20170607”); // 构建数据库事物 TransactionFactory transactionFactory = new JdbcTransactionFactory(); // 创建数据库环境 Environment environment = new Environment(“development”, transactionFactory, dataSource); // 构建Configuration对象 Configuration configuration = new Configuration(environment); // 注册上下文别名 configuration.getTypeAliasRegistry().registerAlias(“role”, MyBatis.class); // 创建映射器 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration); return sqlSessionFactory; }}最后编写测试类package com.ming;import org.junit.After;import org.junit.Before;import org.junit.Test;public class MyBatisTest { private MyBatis myBatis = null; @Before public void setUp() throws Exception { this.myBatis = new MyBatis(); } @After public void tearDown() throws Exception { } @Test public void getSqlSessionFactory() { myBatis.getSqlSessionFactory(); } @Test public void getSqlSessionFactory1() { myBatis.getSqlSessionFactory1(); }}执行单元测试结果如下即完成了MyBatis的一次查询注解定义接口package com.ming;import org.apache.ibatis.annotations.Select;public interface Role1 { @Select (value=“SELECT id, role_name as roleName, note FROM t_role WHERE id = #{id}”) public Role getRole(int id);}生命周期SqlSessionFactoryBuilder其是利用xml或者java编码构建SqlSessionFactory 可以构建多个SessionFactory 作用构建器根据构建器获得sqlSessionFactorySqlSessionFactory创建SqlSession 一个SqlSession相当于JDBC的Connection对象此为单例管理每创建一个SqlSession就会创建一个数据库连接SqlSession此为一个会话,相当于一个Connection连接线程不安全生命周期为一个应用的请求和操作,可以执行多条sql