MyBatis配置文件解析与MyBatis实例演示

@Test

public   void test() throws SQLException {

     Connection conn= null ;

     PreparedStatement pstmt= null ;

     try {

         // 1.加载驱动

         Class.forName( "com.mysql.jdbc.Driver" );

         // 2.创建连接

         conn= DriverManager.

                 getConnection( "jdbc:mysql://localhost:3306/mybatis_example" , "root" , "123456" );

         // SQL语句

         String sql= "select id,user_name,create_time from t_user where id=?" ;

         // 获得sql执行者

         pstmt=conn.prepareStatement(sql);

         pstmt.setInt( 1 , 1 );

         // 执行查询

         //ResultSet rs= pstmt.executeQuery();

         pstmt.execute();

         ResultSet rs= pstmt.getResultSet();

         rs.next();

         User user = new User();

         user.setId(rs.getLong( "id" ));

         user.setUserName(rs.getString( "user_name" ));

         user.setCreateTime(rs.getDate( "create_time" ));

         System.out.println(user.toString());

     } catch (Exception e) {

         e.printStackTrace();

     }

     finally {

         // 关闭资源

         try {

             if (conn!= null ){

                 conn.close();

             }

             if (pstmt!= null ){

                 pstmt.close();

             }

         } catch (SQLException e) {

             e.printStackTrace();

         }

     }

}

public class App {

     public static void main(String[] args) {

         String resource = "mybatis-config.xml" ;

         Reader reader;

         try {

             //将XML配置文件构建为Configuration配置类

             reader = Resources.getResourceAsReader(resource);

             // 通过加载配置文件流构建一个SqlSessionFactory  DefaultSqlSessionFactory

             SqlSessionFactory sqlMapper = new SqlSessionFactoryBuilder().build(reader);

             // 数据源 执行器  DefaultSqlSession

             SqlSession session = sqlMapper.openSession();

             try {

                 // 执行查询 底层执行jdbc

                 //User user = (User)session.selectOne("com.tuling.mapper.selectById", 1);

                 UserMapper mapper = session.getMapper(UserMapper. class );

                 System.out.println(mapper.getClass());

                 User user = mapper.selectById(1L);

                 System.out.println(user.getUserName());

             } catch (Exception e) {

                 e.printStackTrace();

             } finally {

                 session.close();

             }

         } catch (IOException e) {

             e.printStackTrace();

         }

     }

}

<? 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 >

     <!--properties 扫描属性文件.properties  -->

     < properties resource = "db.properties" ></ properties >

     < settings >

         < setting name = "mapUnderscoreToCamelCase" value = "true" />

     </ settings >

    < plugins >

        < plugin interceptor = "com.tuling.plugins.ExamplePlugin" ></ plugin >

     </ plugins >

     < environments default = "development" >

         < environment id = "development" >

            < transactionManager type = "JDBC" />

             <!--//  mybatis内置了JNDI、POOLED、UNPOOLED三种类型的数据源,其中POOLED对应的实现为org.apache.ibatis.datasource.pooled.PooledDataSource,它是mybatis自带实现的一个同步、线程安全的数据库连接池 一般在生产中,我们会使用c3p0或者druid连接池-->

             < dataSource type = "POOLED" >

             < property name = "driver" value = "${mysql.driverClass}" />

             < property name = "url" value = "${mysql.jdbcUrl}" />

             < property name = "username" value = "${mysql.user}" />

             < property name = "password" value = "${mysql.password}" />

         </ dataSource >

         </ environment >

     </ environments >

     < mappers >

         <!--1.必须保证接口名（例如IUserDao）和xml名（IUserDao.xml）相同，还必须在同一个包中-->

         < package name = "com.tuling.mapper" />

         <!--2.不用保证同接口同包同名

          <mapper resource="com/mybatis/mappers/EmployeeMapper.xml"/>

         3.保证接口名（例如IUserDao）和xml名（IUserDao.xml）相同，还必须在同一个包中

         <mapper class="com.mybatis.dao.EmployeeMapper"/>

         4.不推荐:引用网路路径或者磁盘路径下的sql映射文件 file:///var/mappers/AuthorMapper.xml

          <mapper url="file:E:/Study/myeclipse/_03_Test/src/cn/sdut/pojo/PersonMapper.xml"/>-->

     </ mappers >

</ configuration >

< parent >

    < groupId >org.mybatis</ groupId >

    < artifactId >mybatis-parent</ artifactId >

    < version >30</ version >

    < relativePath />

  </ parent >

mvn clean install

mvn clean

mvn install -Dmaven. test .skip= true

<!--

     <plugin>

       <groupId>org.apache.maven.plugins</groupId>

       <artifactId>maven-pdf-plugin</artifactId>

     </plugin>

     -->

< version >3.5.3-xsls</ version >

compile( "org.mybatis:mybatis-spring:2.0.3-xsls" ) 

compile( "org.mybatis:mybatis:3.5.3-xsls" )

< plugin >

   < artifactId >maven-source-plugin</ artifactId >

   < version >3.0.1</ version >

   < configuration >

     < attach >true</ attach >

   </ configuration >

   < executions >

     < execution >

       < phase >compile</ phase >

       < goals >

         < goal >jar</ goal >

       </ goals >

     </ execution >

   </ executions >

</ plugin >

String resource = "mybatis-config.xml" ;

//将XML配置文件构建为Configuration配置类

reader = Resources.getResourceAsReader(resource);

// 通过加载配置文件流构建一个SqlSessionFactory  DefaultSqlSessionFactory

SqlSessionFactory sqlMapper = new SqlSessionFactoryBuilder().build(reader);

//整个过程就是将配置文件解析成Configration对象，然后创建SqlSessionFactory的过程

//Configuration是SqlSessionFactory的一个内部属性

public SqlSessionFactory build(InputStream inputStream, String environment, Properties properties) {

     try {

       XMLConfigBuilder parser = new XMLConfigBuilder(inputStream, environment, properties);

       return build(parser.parse());

     } catch (Exception e) {

       throw ExceptionFactory.wrapException( "Error building SqlSession." , e);

     } finally {

       ErrorContext.instance().reset();

       try {

         inputStream.close();

       } catch (IOException e) {

         // Intentionally ignore. Prefer previous error.

       }

     }

   }

   public SqlSessionFactory build(Configuration config) {

     return new DefaultSqlSessionFactory(config);

   }

<? 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 >

     <!--SqlSessionFactoryBuilder中配置的配置文件的优先级最高；config.properties配置文件的优先级次之；properties标签中的配置优先级最低 -->

     < properties resource = "org/mybatis/example/config.properties" >

       < property name = "username" value = "dev_user" />

       < property name = "password" value = "F2Fa3!33TYyg" />

     </ properties >

     <!--一些重要的全局配置-->

     < settings >

     < setting name = "cacheEnabled" value = "true" />

     <!--<setting name="lazyLoadingEnabled" value="true"/>-->

     <!--<setting name="multipleResultSetsEnabled" value="true"/>-->

     <!--<setting name="useColumnLabel" value="true"/>-->

     <!--<setting name="useGeneratedKeys" value="false"/>-->

     <!--<setting name="autoMappingBehavior" value="PARTIAL"/>-->

     <!--<setting name="autoMappingUnknownColumnBehavior" value="WARNING"/>-->

     <!--<setting name="defaultExecutorType" value="SIMPLE"/>-->

     <!--<setting name="defaultStatementTimeout" value="25"/>-->

     <!--<setting name="defaultFetchSize" value="100"/>-->

     <!--<setting name="safeRowBoundsEnabled" value="false"/>-->

     <!--<setting name="mapUnderscoreToCamelCase" value="false"/>-->

     <!--<setting name="localCacheScope" value="STATEMENT"/>-->

     <!--<setting name="jdbcTypeForNull" value="OTHER"/>-->

     <!--<setting name="lazyLoadTriggerMethods" value="equals,clone,hashCode,toString"/>-->

     <!--<setting name="logImpl" value="STDOUT_LOGGING" />-->

     </ settings >

     < typeAliases >

     </ typeAliases >

     < plugins >

         < plugin interceptor = "com.github.pagehelper.PageInterceptor" >

             <!--默认值为 false，当该参数设置为 true 时，如果 pageSize=0 或者 RowBounds.limit = 0 就会查询出全部的结果-->

             <!--如果某些查询数据量非常大，不应该允许查出所有数据-->

             < property name = "pageSizeZero" value = "true" />

         </ plugin >

     </ plugins >

     < environments default = "development" >

         < environment id = "development" >

             < transactionManager type = "JDBC" />

             < dataSource type = "POOLED" >

                 < property name = "driver" value = "com.mysql.jdbc.Driver" />

                 < property name = "url" value = "jdbc:mysql://10.59.97.10:3308/windty" />

                 < property name = "username" value = "windty_opr" />

                 < property name = "password" value = "windty!234" />

             </ dataSource >

         </ environment >

     </ environments >

     < databaseIdProvider type = "DB_VENDOR" >

         < property name = "MySQL" value = "mysql" />

         < property name = "Oracle" value = "oracle" />

     </ databaseIdProvider >

     < mappers >

         <!--这边可以使用package和resource两种方式加载mapper-->

         <!--<package name="包名"/>-->

         <!--<mapper resource="./mappers/SysUserMapper.xml"/>-->

         < mapper resource = "./mappers/CbondissuerMapper.xml" />

     </ mappers >

</ configuration >

private void parseConfiguration(XNode root) {

     try {

       //issue #117 read properties first

       //解析properties标签，并set到Configration对象中

       //在properties配置属性后，在Mybatis的配置文件中就可以使用${key}的形式使用了。

       propertiesElement(root.evalNode( "properties" ));

       //解析setting标签的配置

       Properties settings = settingsAsProperties(root.evalNode( "settings" ));

       //添加vfs的自定义实现，这个功能不怎么用

       loadCustomVfs(settings);

       //配置类的别名，配置后就可以用别名来替代全限定名

       //mybatis默认设置了很多别名，参考附录部分

       typeAliasesElement(root.evalNode( "typeAliases" ));

       //解析拦截器和拦截器的属性，set到Configration的interceptorChain中

       //MyBatis 允许你在已映射语句执行过程中的某一点进行拦截调用。默认情况下，MyBatis 允许使用插件来拦截的方法调用包括：

       //Executor (update, query, flushStatements, commit, rollback, getTransaction, close, isClosed)

         //ParameterHandler (getParameterObject, setParameters)

         //ResultSetHandler (handleResultSets, handleOutputParameters)

         //StatementHandler (prepare, parameterize, batch, update, query)

       pluginElement(root.evalNode( "plugins" ));

       //Mybatis创建对象是会使用objectFactory来创建对象，一般情况下不会自己配置这个objectFactory，使用系统默认的objectFactory就好了

       objectFactoryElement(root.evalNode( "objectFactory" ));

       objectWrapperFactoryElement(root.evalNode( "objectWrapperFactory" ));

       reflectorFactoryElement(root.evalNode( "reflectorFactory" ));

       //设置在setting标签中配置的配置

       settingsElement(settings);

       //解析环境信息，包括事物管理器和数据源，SqlSessionFactoryBuilder在解析时需要指定环境id，如果不指定的话，会选择默认的环境；

       //最后将这些信息set到Configration的Environment属性里面

       environmentsElement(root.evalNode( "environments" ));

       //

       databaseIdProviderElement(root.evalNode( "databaseIdProvider" ));

       //无论是 MyBatis 在预处理语句（PreparedStatement）中设置一个参数时，还是从结果集中取出一个值时， 都会用类型处理器将获取的值以合适的方式转换成 Java 类型。解析typeHandler。

       typeHandlerElement(root.evalNode( "typeHandlers" ));

       //解析Mapper

       mapperElement(root.evalNode( "mappers" ));

     } catch (Exception e) {

       throw new BuilderException( "Error parsing SQL Mapper Configuration. Cause: " + e, e);

     }

}