1，这里我用了tk mapper为例，我们首先看MapperAutoConfiguration类，它给我们注入了一个SqlSessionTemplate

@Bean    @ConditionalOnMissingBean    public SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {        ExecutorType executorType = this.properties.getExecutorType();        if (executorType != null) {            return new SqlSessionTemplate(sqlSessionFactory, executorType);        } else {            return new SqlSessionTemplate(sqlSessionFactory);        }    }

2，目光转移到SqlSessionTemplate，看其构造方法，发现它使用了一个代理，而实际的增删改查方法，实际是靠代理来执行的

public SqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType,      PersistenceExceptionTranslator exceptionTranslator) {//...    this.sqlSessionFactory = sqlSessionFactory;    this.executorType = executorType;    this.exceptionTranslator = exceptionTranslator;    this.sqlSessionProxy = (SqlSession) newProxyInstance(        SqlSessionFactory.class.getClassLoader(),        new Class[] { SqlSession.class },        new SqlSessionInterceptor());  } public 
    
      T selectOne(String statement) {    return this.sqlSessionProxy.
     
       selectOne(statement);  }  public 
      
        List
       
         selectList(String statement) {    return this.sqlSessionProxy.
        
          selectList(statement);  }  public int update(String statement) {    return this.sqlSessionProxy.update(statement);  }
        
       
      
     
    

3，目光转移到SqlSessionInterceptor，相信看到这里，各位小伙伴都廓然开朗了吧，原来就是这个拦截器，帮我们获取提交和关闭SqlSession

private class SqlSessionInterceptor implements InvocationHandler {    @Override    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {      SqlSession sqlSession = getSqlSession(          SqlSessionTemplate.this.sqlSessionFactory,          SqlSessionTemplate.this.executorType,          SqlSessionTemplate.this.exceptionTranslator);      try {        Object result = method.invoke(sqlSession, args);        if (!isSqlSessionTransactional(sqlSession, SqlSessionTemplate.this.sqlSessionFactory)) {          // force commit even on non-dirty sessions because some databases require          // a commit/rollback before calling close()          sqlSession.commit(true);        }        return result;      } catch (Throwable t) {        Throwable unwrapped = unwrapThrowable(t);        if (SqlSessionTemplate.this.exceptionTranslator != null && unwrapped instanceof PersistenceException) {          // release the connection to avoid a deadlock if the translator is no loaded. See issue #22          closeSqlSession(sqlSession, SqlSessionTemplate.this.sqlSessionFactory);          sqlSession = null;          Throwable translated = SqlSessionTemplate.this.exceptionTranslator.translateExceptionIfPossible((PersistenceException) unwrapped);          if (translated != null) {            unwrapped = translated;          }        }        throw unwrapped;      } finally {        if (sqlSession != null) {          closeSqlSession(sqlSession, SqlSessionTemplate.this.sqlSessionFactory);        }      }    }  }