• 2mybatis-1条sql在mybatis的执行过程


    MapperProxy --|》MapperMethod --|》 SqlSession 调用sh去执行ms -> PreparedStatementHandler 解析出stmt,然后执行stmt -> resultSetHandler解析结果

    MapperProxy

    Map<Method, MapperMethod> methodCache;

    MapperMethod mapperMethod = cachedMapperMethod(method);
    从methodCache获取mapper里的一个方法

    return mapperMethod.execute(sqlSession, args);

    MapperMethod

    SqlCommand 封装了sql的类型,方法名
    MethodSignature 方法的返回值、参数

    Object execute(SqlSession sqlSession, Object[] args){...}
    执行方法

    Object param = method.convertArgsToSqlCommandParam(args);
    解析方法参数

    result = rowCountResult(sqlSession.insert(command.getName(), param));
    解析方法结果

    result = sqlSession.selectOne(command.getName(), param);
    通过sqlSession执行方法

    result = executeForMany(sqlSession, args);
    执行List<结果>查询

    Object executeForMany(SqlSession sqlSession, Object[] args) {..}

    result = sqlSession.selectList(command.getName(), param);

    DefaultSqlSession

    public List selectList(String statement/** 这个类名+方法名+参数*/, Object parameter) {..}

    return this.selectList(statement, parameter, RowBounds.DEFAULT);

    public List selectList(String statement, Object parameter, RowBounds rowBounds) {...}

    MappedStatement ms = configuration.getMappedStatement(statement);
    从configuration中获取MappedStatement

    return executor.query(ms, wrapCollection(parameter), rowBounds, Executor.NO_RESULT_HANDLER);
    executor执行查询

    CachingExecutor

    public List query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler) {...}

    BoundSql boundSql = ms.getBoundSql(parameterObject);
    在MappedStatement获取BoundSql

    CacheKey key = createCacheKey(ms, parameterObject, rowBounds, boundSql);
    创建CacheKey

    return query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);

    public List query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql){...}

    Cache cache = ms.getCache();
    在MappedStatement中查找是否有缓存

    BaseExecutor

    public List query(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql) throws SQLException {...}

    list = queryFromDatabase(ms, parameter, rowBounds, resultHandler, key, boundSql);
    缓存中没有,从数据中查询

    private List queryFromDatabase(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql) throws SQLException {...}

    list = doQuery(ms, parameter, rowBounds, resultHandler, boundSql);
    使用SimpleExecutor执行查询,并返回结果,
    SimpleExecutor -》 StatementHandler(不同类型的StatementHandler)具体执行

    SimpleExecutor

    public List doQuery(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {...}

    Configuration configuration = ms.getConfiguration();

    StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, resultHandler, boundSql);
    获取一个RoutingStatementHandler

    stmt = prepareStatement(handler, ms.getStatementLog());
    制作stmt

    return handler.query(stmt, resultHandler);
    在StatementHandler中执行jdbc的stmt,并返回查询结果

    -finally closeStatement(stmt);
    关闭statement

    Configuration

    protected final Map<String, MappedStatement> mappedStatements = new StrictMap("Mapped Statements collection");

    public MappedStatement getMappedStatement(String id, boolean validateIncompleteStatements) {...}

    return mappedStatements.get(id);//id是com.roncoo.eshop.inventory.mapper.UserMapper.findUserInfo
    从全局Map mappedStatements获取MappedStatement

    public StatementHandler newStatementHandler(Executor executor, MappedStatement mappedStatement, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) {...}

    StatementHandler statementHandler = new RoutingStatementHandler(executor, mappedStatement, parameterObject, rowBounds, resultHandler, boundSql);
    创建一个RoutingStatementHandler

    statementHandler = (StatementHandler) interceptorChain.pluginAll(statementHandler);
    这里也有拦截,new executor时给它增强类似,,返回一个增强过后的实例

    MappedStatement

    存放了一个mapper的元素信息,比如useCache、List resultMaps、参数等

    StatementHandler

    制作statement,返回给exector调用

    RoutingStatementHandler

    构造函数
    根据不同的ms.getStatementType() STATEMENT、PREPARED、CALLABLE 创建SimpleStatementHandler/PreparedStatementHandler/CallableStatementHandler

    PreparedStatementHandler

    public List query(Statement statement, ResultHandler resultHandler) throws SQLException {...}

    PreparedStatement ps = (PreparedStatement) statement;
    在PreparedStatementHandler中获取PreparedStatement

    ps.execute();
    执行请求

    return resultSetHandler. handleResultSets(ps);
    返回结果

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  • 原文地址:https://www.cnblogs.com/kltsee/p/15101477.html
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