说明

读了3遍:https://my.oschina.net/zudajun/blog/665956 现在统一整理成笔记并跟着源码一行一行调试统一整理起来

SqlSession

接口定义

public interface SqlSession extends Closeable {

    <T> T selectOne(String var1);

    <T> T selectOne(String var1, Object var2);

    <E> List<E> selectList(String var1);

    <E> List<E> selectList(String var1, Object var2);

    <E> List<E> selectList(String var1, Object var2, RowBounds var3);

    <K, V> Map<K, V> selectMap(String var1, String var2);

    <K, V> Map<K, V> selectMap(String var1, Object var2, String var3);

    <K, V> Map<K, V> selectMap(String var1, Object var2, String var3, RowBounds var4);

    <T> Cursor<T> selectCursor(String var1);

    <T> Cursor<T> selectCursor(String var1, Object var2);

    <T> Cursor<T> selectCursor(String var1, Object var2, RowBounds var3);

    void select(String var1, Object var2, ResultHandler var3);

    void select(String var1, ResultHandler var2);

    void select(String var1, Object var2, RowBounds var3, ResultHandler var4);

    int insert(String var1);

    int insert(String var1, Object var2);

    int update(String var1);

    int update(String var1, Object var2);

    int delete(String var1);

    int delete(String var1, Object var2);

    void commit();

    void commit(boolean var1);

    void rollback();

    void rollback(boolean var1);

    List<BatchResult> flushStatements();

    void close();

    void clearCache();

    Configuration getConfiguration();

    <T> T getMapper(Class<T> var1);

    Connection getConnection();

}

完成数据库CRUD操作

实现类结构图

DefaultSqlSession部分源码

 //执行器 接口

    private Executor executor;

    //配置文件 类

    private Configuration configuration;

    /***

     * 查询方法

     * @param statement mapper.xml namesapce+id

     * @param parameter 查询参数

     * @param rowBounds 分页参数 解析返回值的handler

     */

    public <E> List<E> selectList(String statement, Object parameter, RowBounds rowBounds) {

        List var5;

        try {

            //从config根据 namesapce+id 获得对应的mappedStatement 然后交给executor的query方法

            MappedStatement ms = this.configuration.getMappedStatement(statement);

            var5 = this.executor.query(ms, this.wrapCollection(parameter), rowBounds, Executor.NO_RESULT_HANDLER);

        } catch (Exception var9) {

            throw ExceptionFactory.wrapException("Error querying database.  Cause: " + var9, var9);

        } finally {

            ErrorContext.instance().reset();

        }

        return var5;

    }

    /**

     * 修改方法 增加删除也是最终调用这个方法

     * @param statement mapper.xml namesapce+id

     * @param parameter 参数

     * @return

     */

    public int update(String statement, Object parameter) {

        int var4;

        try {

            this.dirty = true;

            //从config根据 namesapce+id 获得对应的mappedStatement 然后交给executor的query方法

            MappedStatement ms = this.configuration.getMappedStatement(statement);

            var4 = this.executor.update(ms, this.wrapCollection(parameter));

        } catch (Exception var8) {

            throw ExceptionFactory.wrapException("Error updating database.  Cause: " + var8, var8);

        } finally {

            ErrorContext.instance().reset();

        }

        return var4;

    }

职责是根据namesapce+id 获得对应的mappedStatement然后交给executor执行

SqlSessionFactory

接口定义

public interface SqlSessionFactory {

    SqlSession openSession();

    SqlSession openSession(boolean var1);

    SqlSession openSession(Connection var1);

    SqlSession openSession(TransactionIsolationLevel var1);

    SqlSession openSession(ExecutorType var1);

    SqlSession openSession(ExecutorType var1, boolean var2);

    SqlSession openSession(ExecutorType var1, TransactionIsolationLevel var2);

    SqlSession openSession(ExecutorType var1, Connection var2);

    Configuration getConfiguration();

}

sqlSession工厂

类图

DefaultSqlSessionFactory源码

public class DefaultSqlSessionFactory implements SqlSessionFactory {

    //配置文件 保存了解析的mybaits.xml和mapper.xml的内容

    private final Configuration configuration;

    /**

     * openSession()最终都是调用这个方法创建Session

     * @param execType 执行器

     * @param level 事物隔离级别

     * @param autoCommit 是否自动提交

     * @return

     */

    private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit) {

        Transaction tx = null;

        DefaultSqlSession var8;

        try {

            //根据配置文件获得Environment 内部封装了数据源信息和事物管理器Factory  environments标签配置

            Environment environment = this.configuration.getEnvironment();

            //获得对应的事物管理器

            TransactionFactory transactionFactory = this.getTransactionFactoryFromEnvironment(environment);

            //开启事物

            tx = transactionFactory.newTransaction(environment.getDataSource(), level, autoCommit);

            //创建执行器

            Executor executor = this.configuration.newExecutor(tx, execType);

            //创建DefaultSqlSession

            var8 = new DefaultSqlSession(this.configuration, executor, autoCommit);

        } catch (Exception var12) {

            this.closeTransaction(tx);

            throw ExceptionFactory.wrapException("Error opening session.  Cause: " + var12, var12);

        } finally {

            ErrorContext.instance().reset();

        }

        return var8;

    }

    /**

     * 判断是否有指定事物管理创建工厂 如果没有指定 则默认ManagedTransactionFactory environments标签配置

     * @param environment

     * @return

     */

    private TransactionFactory getTransactionFactoryFromEnvironment(Environment environment) {

        return (TransactionFactory)(environment != null && environment.getTransactionFactory() != null ? environment.getTransactionFactory() : new ManagedTransactionFactory());

    }

}

SqlSessionManager

使用

执行完后自动提交回滚创建2个session

  public static void main(String[] args) throws FileNotFoundException {

        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();

        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder

                .build(ClassLoader.getSystemResourceAsStream("mybatis.xml"));

        SqlSessionManager sqlSessionManager = SqlSessionManager.newInstance(sqlSessionFactory);

        List<Classes> list = sqlSessionManager.selectList("classes.selectAll");

        list = sqlSessionManager.selectList("classes.selectAll");

    }

创建一个session手动提交回滚

public static void main(String[] args) throws FileNotFoundException {

        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();

        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder

                .build(ClassLoader.getSystemResourceAsStream("mybatis.xml"));

        SqlSessionManager sqlSessionManager=null;

        try {

            sqlSessionManager.startManagedSession();

            List<Classes> list = sqlSessionManager.selectList("classes.selectAll");

            list = sqlSessionManager.selectList("classes.selectAll");

            sqlSessionManager.commit();

        }catch (Exception e) {

            if(sqlSessionManager!=null) {

                sqlSessionManager.rollback();

            }

        }

    }

类图

源码

public class SqlSessionManager implements SqlSessionFactory, SqlSession {

    private final SqlSessionFactory sqlSessionFactory;

    //被代理的sqlSeesion

    private final SqlSession sqlSessionProxy;

    //线程缓存

    private ThreadLocal<SqlSession> localSqlSession = new ThreadLocal();

    private SqlSessionManager(SqlSessionFactory sqlSessionFactory) {

        this.sqlSessionFactory = sqlSessionFactory;

        //代理sqlSession 第一个参数类装载器 第二个参数哪个接口类型被代理  第三个参数为代理类 为SqlSessionManager内部内

        this.sqlSessionProxy = (SqlSession) Proxy.newProxyInstance(SqlSessionFactory.class.getClassLoader(), new Class[]{SqlSession.class}, new SqlSessionManager.SqlSessionInterceptor());

    }

    public <T> T selectOne(String statement, Object parameter) {

        return this.sqlSessionProxy.selectOne(statement, parameter);

    }

    public int insert(String statement) {

        return this.sqlSessionProxy.insert(statement);

    }

    public int update(String statement, Object parameter) {

        return this.sqlSessionProxy.update(statement, parameter);

    }

    public int delete(String statement) {

        return this.sqlSessionProxy.delete(statement);

    }

　　public SqlSession openSession() {
    return this.sqlSessionFactory.openSession();
　　}

内部类SqlSessionInterceptor源码

 private class SqlSessionInterceptor implements InvocationHandler {

        public SqlSessionInterceptor() {

        }

        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

            //从当前线程获得SqlSession 如果为空则创建不为空则直接使用缓存中的SqlSession

            SqlSession sqlSession = (SqlSession)SqlSessionManager.this.localSqlSession.get();

            if (sqlSession != null) {

                try {

                    //直接使用线程缓存中的SqlSession 并不提交不回滚

                    return method.invoke(sqlSession, args);

                } catch (Throwable var12) {

                    throw ExceptionUtil.unwrapThrowable(var12);

                }

            } else {

                //调用SqlSessionManager的openSession方法获得SqlSession 执行完毕后提交回滚

                SqlSession autoSqlSession = SqlSessionManager.this.openSession();

                Object var7;

                try {

                    Object result = method.invoke(autoSqlSession, args);

                    autoSqlSession.commit();

                    var7 = result;

                } catch (Throwable var13) {

                    autoSqlSession.rollback();

                    throw ExceptionUtil.unwrapThrowable(var13);

                } finally {

                    autoSqlSession.close();

                }

                return var7;

            }

        }

    }

巴特西

mybatis源码阅读-SqlSessionFactory和SqlSession(三)

说明

SqlSession

接口定义

实现类结构图

DefaultSqlSession部分源码

SqlSessionFactory

接口定义

类图

DefaultSqlSessionFactory源码

SqlSessionManager

使用

类图

源码

内部类SqlSessionInterceptor源码

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