Mybatis是怎麼執行一條語句的
阿新 • • 發佈:2020-11-05
根據官方的推薦方式,通過mapper的方式執行sql,mapper的方式就是動態代理
所以,我們就先看動態代理的入口
一MapperMethod
public class MapperProxy<T> implements InvocationHandler, Serializable { private static final long serialVersionUID = -6424540398559729838L; private final SqlSession sqlSession; private final Class<T> mapperInterface;private final Map<Method, MapperMethod> methodCache; public MapperProxy(SqlSession sqlSession, Class<T> mapperInterface, Map<Method, MapperMethod> methodCache) { this.sqlSession = sqlSession; this.mapperInterface = mapperInterface; this.methodCache = methodCache; } @Overridepublic Object invoke(Object proxy, Method method, Object[] args) throws Throwable { if (Object.class.equals(method.getDeclaringClass())) { try { return method.invoke(this, args); } catch (Throwable t) { throw ExceptionUtil.unwrapThrowable(t); } } final MapperMethod mapperMethod = cachedMapperMethod(method);return mapperMethod.execute(sqlSession, args); }
結論就是 從MapperMethod開始執行
二 SqlSession
public Object execute(SqlSession sqlSession, Object[] args) { Object result; if (SqlCommandType.INSERT == command.getType()) { Object param = method.convertArgsToSqlCommandParam(args); result = rowCountResult(sqlSession.insert(command.getName(), param));
三 Executor
@Override public int update(String statement, Object parameter) { try { dirty = true; MappedStatement ms = configuration.getMappedStatement(statement); return executor.update(ms, wrapCollection(parameter)); } catch (Exception e) { throw ExceptionFactory.wrapException("Error updating database. Cause: " + e, e); } finally { ErrorContext.instance().reset(); } }
四 StatementHandler
@Override public int doUpdate(MappedStatement ms, Object parameter) throws SQLException { Configuration configuration = ms.getConfiguration(); StatementHandler handler = configuration.newStatementHandler(this, ms, parameter, RowBounds.DEFAULT, null, null); Statement stmt = prepareStatement(handler, ms.getStatementLog()); return handler.update(stmt); }
總結就是,mybatis的執行鏈路,
1 MapperMethod
2 SqlSession
3 Executor
4 StatementHandler