spring-mybatis與mybatis區別

1，spring-mybatis一級緩存失效，因爲是sqlsesstionTemplate，其使用了一個代理proxysession，每次請求都會關閉session;

spring-mybatis擴展了一個類sqlsessiontemplate，這個類在spring容器啓動時被注入給mapper， 這個類替代了原來的mybatis的DefaultSqlSession，sqlsessiontemplate的所有查詢並不直接查詢，而是經過一個代理對象，代理對象增加了查詢方法，主要是每次關閉了session

 

public SqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType, PersistenceExceptionTranslator exceptionTranslator) {
    Assert.notNull(sqlSessionFactory, "Property 'sqlSessionFactory' is required");
    Assert.notNull(executorType, "Property 'executorType' is required");
    this.sqlSessionFactory = sqlSessionFactory;
    this.executorType = executorType;
    this.exceptionTranslator = exceptionTranslator;
    this.sqlSessionProxy = (SqlSession)Proxy.newProxyInstance(SqlSessionFactory.class.getClassLoader(), new Class[]{SqlSession.class}, new SqlSessionTemplate.SqlSessionInterceptor());
}

............

private class SqlSessionInterceptor implements InvocationHandler {
    private SqlSessionInterceptor() {
    }

    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        SqlSession sqlSession = SqlSessionUtils.getSqlSession(SqlSessionTemplate.this.sqlSessionFactory, SqlSessionTemplate.this.executorType, SqlSessionTemplate.this.exceptionTranslator);

        Object unwrapped;
        try {
            Object result = method.invoke(sqlSession, args);//其中sqlsession是mybatis的defaultSession,加了代理是爲增加關閉功能
            if (!SqlSessionUtils.isSqlSessionTransactional(sqlSession, SqlSessionTemplate.this.sqlSessionFactory)) {
                sqlSession.commit(true);
            }

            unwrapped = result;
        } catch (Throwable var11) {
            unwrapped = ExceptionUtil.unwrapThrowable(var11);
            if (SqlSessionTemplate.this.exceptionTranslator != null && unwrapped instanceof PersistenceException) {
                SqlSessionUtils.closeSqlSession(sqlSession, SqlSessionTemplate.this.sqlSessionFactory);
                sqlSession = null;
                Throwable translated = SqlSessionTemplate.this.exceptionTranslator.translateExceptionIfPossible((PersistenceException)unwrapped);
                if (translated != null) {
                    unwrapped = translated;
                }
            }

            throw (Throwable)unwrapped;
        } finally {
            if (sqlSession != null) { //每次都會關閉
                SqlSessionUtils.closeSqlSession(sqlSession, SqlSessionTemplate.this.sqlSessionFactory);
            }

        }

        return unwrapped;
    }
}

 

2，mybatis的sqlsession是defaultSqlSession，是實類，同一個session不關閉，直到結束，session暴露在代碼，可以隨時close, 相當於關閉session可控

而spring-mybatis的每次session要關閉是因爲session不在ioc容器中,加上集成後無接口關閉session,沒暴露api，所以使用代理增加了關閉session,   所以爲了資源的可重複利用，防止不關，每次要關閉