Mybatis源码分析[05.Configuration]

Mybatis的配置类

public class Configuration {  //环境  protected Environment environment;  //---------节点-------  protected boolean safeRowBoundsEnabled = false;  protected boolean safeResultHandlerEnabled = true;  protected boolean mapUnderscoreToCamelCase = false;  protected boolean aggressiveLazyLoading = true;  protected boolean multipleResultSetsEnabled = true;  protected boolean useGeneratedKeys = false;  protected boolean useColumnLabel = true;  //默认启用缓存  protected boolean cacheEnabled = true;  protected boolean callSettersOnNulls = false;  protected String logPrefix;  protected Class  logImpl;  protected LocalCacheScope localCacheScope = LocalCacheScope.SESSION;  protected JdbcType jdbcTypeForNull = JdbcType.OTHER;  protected Set lazyLoadTriggerMethods = new HashSet(Arrays.asList(new String[] { "equals", "clone", "hashCode", "toString" }));  protected Integer defaultStatementTimeout;  //默认为简单执行器  protected ExecutorType defaultExecutorType = ExecutorType.SIMPLE;  protected AutoMappingBehavior autoMappingBehavior = AutoMappingBehavior.PARTIAL;  //---------节点-------  protected Properties variables = new Properties();  //对象工厂和对象包装器工厂  protected ObjectFactory objectFactory = new DefaultObjectFactory();  protected ObjectWrapperFactory objectWrapperFactory = new DefaultObjectWrapperFactory();  //映射注册机  protected MapperRegistry mapperRegistry = new MapperRegistry(this);  //默认禁用延迟加载  protected boolean lazyLoadingEnabled = false;  protected ProxyFactory proxyFactory = new JavassistProxyFactory(); // #224 Using internal Javassist instead of OGNL  protected String databaseId;  /**   * Configuration factory class.   * Used to create Configuration for loading deserialized unread properties.   *   * @see Issue 300 (google code)   */  protected Class configurationFactory;  protected final InterceptorChain interceptorChain = new InterceptorChain();  //类型处理器注册机  protected final TypeHandlerRegistry typeHandlerRegistry = new TypeHandlerRegistry();  //类型别名注册机  protected final TypeAliasRegistry typeAliasRegistry = new TypeAliasRegistry();  protected final LanguageDriverRegistry languageRegistry = new LanguageDriverRegistry();  //映射的语句,存在Map里  protected final Map mappedStatements = new StrictMap("Mapped Statements collection");  //缓存,存在Map里  protected final Map caches = new StrictMap("Caches collection");  //结果映射,存在Map里  protected final Map resultMaps = new StrictMap("Result Maps collection");  protected final Map parameterMaps = new StrictMap("Parameter Maps collection");  protected final Map keyGenerators = new StrictMap("Key Generators collection");  protected final Set loadedResources = new HashSet();  protected final Map sqlFragments = new StrictMap("XML fragments parsed from previous mappers");  //不完整的SQL语句  protected final Collection incompleteStatements = new LinkedList();  protected final Collection incompleteCacheRefs = new LinkedList();  protected final Collection incompleteResultMaps = new LinkedList();  protected final Collection incompleteMethods = new LinkedList();  /*   * A map holds cache-ref relationship. The key is the namespace that   * references a cache bound to another namespace and the value is the   * namespace which the actual cache is bound to.   */  protected final Map cacheRefMap = new HashMap();  public Configuration(Environment environment) {    this();    this.environment = environment;  }  public Configuration() {    //注册更多的类型别名    typeAliasRegistry.registerAlias("JDBC", JdbcTransactionFactory.class);    typeAliasRegistry.registerAlias("MANAGED", ManagedTransactionFactory.class);    typeAliasRegistry.registerAlias("JNDI", JndiDataSourceFactory.class);    typeAliasRegistry.registerAlias("POOLED", PooledDataSourceFactory.class);    typeAliasRegistry.registerAlias("UNPOOLED", UnpooledDataSourceFactory.class);    typeAliasRegistry.registerAlias("PERPETUAL", PerpetualCache.class);    typeAliasRegistry.registerAlias("FIFO", FifoCache.class);    typeAliasRegistry.registerAlias("LRU", LruCache.class);    typeAliasRegistry.registerAlias("SOFT", SoftCache.class);    typeAliasRegistry.registerAlias("WEAK", WeakCache.class);    typeAliasRegistry.registerAlias("DB_VENDOR", VendorDatabaseIdProvider.class);    typeAliasRegistry.registerAlias("XML", XMLLanguageDriver.class);    typeAliasRegistry.registerAlias("RAW", RawLanguageDriver.class);    typeAliasRegistry.registerAlias("SLF4J", Slf4jImpl.class);    typeAliasRegistry.registerAlias("COMMONS_LOGGING", JakartaCommonsLoggingImpl.class);    typeAliasRegistry.registerAlias("LOG4J", Log4jImpl.class);    typeAliasRegistry.registerAlias("LOG4J2", Log4j2Impl.class);    typeAliasRegistry.registerAlias("JDK_LOGGING", Jdk14LoggingImpl.class);    typeAliasRegistry.registerAlias("STDOUT_LOGGING", StdOutImpl.class);    typeAliasRegistry.registerAlias("NO_LOGGING", NoLoggingImpl.class);    typeAliasRegistry.registerAlias("CGLIB", CglibProxyFactory.class);    typeAliasRegistry.registerAlias("JAVASSIST", JavassistProxyFactory.class);    languageRegistry.setDefaultDriverClass(XMLLanguageDriver.class);    languageRegistry.register(RawLanguageDriver.class);  }}

Configuration类具有产生执行器的功能

  //产生执行器  public Executor newExecutor(Transaction transaction, ExecutorType executorType) {    executorType = executorType == null ? defaultExecutorType : executorType;    executorType = executorType == null ? ExecutorType.SIMPLE : executorType;    Executor executor;    //然后就是简单的3个分支，产生3种执行器BatchExecutor/ReuseExecutor/SimpleExecutor    if (ExecutorType.BATCH == executorType) {      executor = new BatchExecutor(this, transaction);    } else if (ExecutorType.REUSE == executorType) {      executor = new ReuseExecutor(this, transaction);    } else {      executor = new SimpleExecutor(this, transaction);    }    //如果要求缓存，生成另一种CachingExecutor(默认就是有缓存),装饰者模式,所以默认都是返回CachingExecutor    if (cacheEnabled) {      executor = new CachingExecutor(executor);    }    //此处调用插件,通过插件可以改变Executor行为    executor = (Executor) interceptorChain.pluginAll(executor);    return executor;  }