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Mybati源码解析篇之六剑客!!!

作者：互联网

目录

前言

环境版本

Myabtis的六剑客

SqlSession

有何方法

语句执行方法

<T> T selectOne(String statement, Object parameter)
<E> List<E> selectList(String statement, Object parameter)
<T> Cursor<T> selectCursor(String statement, Object parameter)
<K,V> Map<K,V> selectMap(String statement, Object parameter, String mapKey)
int insert(String statement, Object parameter)
int update(String statement, Object parameter)
int delete(String statement, Object parameter)

<E> List<E> selectList (String statement, Object parameter, RowBounds rowBounds)
<T> Cursor<T> selectCursor(String statement, Object parameter, RowBounds rowBounds)
<K,V> Map<K,V> selectMap(String statement, Object parameter, String mapKey, RowBounds rowbounds)
void select (String statement, Object parameter, ResultHandler<T> handler)
void select (String statement, Object parameter, RowBounds rowBounds, ResultHandler<T> handler)

立即批量更新方法

List<BatchResult> flushStatements()

事务控制方法

void commit()
void commit(boolean force)
void rollback()
void rollback(boolean force)

本地缓存方法

void clearCache()

获取映射器

<T> T getMapper(Class<T> type)

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

有何实现类

@Bean
  @ConditionalOnMissingBean
  public SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) 
    //根据执行器的类型创建不同的执行器，默认CachingExecutor
    ExecutorType executorType = this.properties.getExecutorType();
    if (executorType != null) {
      return new SqlSessionTemplate(sqlSessionFactory, executorType);
    } else {
      return new SqlSessionTemplate(sqlSessionFactory);
    }
  }

Executor

实现类

BaseExecutor

private <E> List<E> queryFromDatabase(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql) throws SQLException {
    List<E> list;
    //此处的localCache即是一级缓存，是一个Map的结构
    localCache.putObject(key, EXECUTION_PLACEHOLDER);
    try {
      //执行真正的查询
      list = doQuery(ms, parameter, rowBounds, resultHandler, boundSql);
    } finally {
      localCache.removeObject(key);
    }
    localCache.putObject(key, list);
    if (ms.getStatementType() == StatementType.CALLABLE) {
      localOutputParameterCache.putObject(key, parameter);
    }
    return list;
  }

CachingExecutor

@Override
  public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql)
      throws SQLException {
    //查看当前Sql是否使用了二级缓存
    Cache cache = ms.getCache();
    //使用缓存了，直接从缓存中取
    if (cache != null) {
      flushCacheIfRequired(ms);
      if (ms.isUseCache() && resultHandler == null) {
        ensureNoOutParams(ms, boundSql);
        @SuppressWarnings("unchecked")
        //从缓存中取数据
        List<E> list = (List<E>) tcm.getObject(cache, key);
        if (list == null) {
          //没取到数据，则执行SQL从数据库查询
          list = delegate.query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
          //查到了，放入缓存中
          tcm.putObject(cache, key, list); // issue #578 and #116
        }
        //直接返回
        return list;
      }
    }
    //没使用二级缓存，直接执行SQL从数据库查询
    return delegate.query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
  }

SimpleExecutor

BatchExecutor

ReuseExecutor

SpringBoot中如何创建

public Executor newExecutor(Transaction transaction, ExecutorType executorType) {
    //没有指定执行器的类型，创建默认的，即是SimpleExecutor
    executorType = executorType == null ? defaultExecutorType : executorType;
    executorType = executorType == null ? ExecutorType.SIMPLE : executorType;
    Executor executor;
    //类型是BATCH，创建BatchExecutor
    if (ExecutorType.BATCH == executorType) {
      executor = new BatchExecutor(this, transaction);
      //类型为REUSE，创建ReuseExecutor
    } else if (ExecutorType.REUSE == executorType) {
      executor = new ReuseExecutor(this, transaction);
    } else {
      //除了上面两种，创建的都是SimpleExecutor
      executor = new SimpleExecutor(this, transaction);
    }
    //如果全局配置了二级缓存，则创建CachingExecutor，SpringBoot中这个参数默认是true，可以自己设置为false
    if (cacheEnabled) {
    //创建CachingExecutor
      executor = new CachingExecutor(executor);
    }
    executor = (Executor) interceptorChain.pluginAll(executor);
    return executor;
  }

StatementHandler

实现类

SimpleStatementHandler

PreparedStatementHandler

CallableStatementHandler

RoutingStatementHandler

ParameterHandler

TypeHandler

ResultSetHandler

总结

标签：Mybati,缓存,String,方法,Object,剑客,Mybatis,parameter,源码
来源： https://www.cnblogs.com/Chenjiabing/p/13644884.html