Mybatis初始化配置

JerryXia 发表于 2019-01-28 18:30:30 , 阅读 (0)

我们可以从SqlSessionTest单元测试的Setup开始

private static SqlSessionFactory sqlMapper;@BeforeClasspublic static void setup() throws Exception {    createBlogDataSource();    final String resource = "org/apache/ibatis/builder/MapperConfig.xml";    final Reader reader = Resources.getResourceAsReader(resource);    sqlMapper = new SqlSessionFactoryBuilder().build(reader);}

MapperConfig.xml文件:

<configuration>    <properties resource="databases/blog/blog-derby.properties"/>    <!-- 配置信息 -->    <settings>        <setting name="cacheEnabled" value="true"/>        <setting name="lazyLoadingEnabled" value="false"/>        <setting name="multipleResultSetsEnabled" value="true"/>        <setting name="useColumnLabel" value="true"/>        <setting name="useGeneratedKeys" value="false"/>        <setting name="defaultExecutorType" value="SIMPLE"/>        <setting name="defaultStatementTimeout" value="25"/>    </settings>    <!-- 类型别名配置 -->    <typeAliases>        <typeAlias alias="Author" type="domain.blog.Author"/>        <typeAlias alias="Blog" type="domain.blog.Blog"/>        <typeAlias alias="Comment" type="domain.blog.Comment"/>        <typeAlias alias="Post" type="domain.blog.Post"/>        <typeAlias alias="Section" type="domain.blog.Section"/>        <typeAlias alias="Tag" type="domain.blog.Tag"/>    </typeAliases>    <!-- 类型处理器 -->    <typeHandlers>        <typeHandler javaType="String" jdbcType="VARCHAR" handler="org.apache.ibatis.builder.ExampleTypeHandler"/>    </typeHandlers>    <!-- 对象工场 -->    <objectFactory type="org.apache.ibatis.builder.ExampleObjectFactory">        <property name="objectFactoryProperty" value="100"/>    </objectFactory>    <!-- 插件配置 -->    <plugins>        <plugin interceptor="org.apache.ibatis.builder.ExamplePlugin">            <property name="pluginProperty" value="100"/>        </plugin>    </plugins>    <!-- 环境配置 -->    <environments default="development">        <environment id="development">            <transactionManager type="JDBC">                <property name="" value=""/>            </transactionManager>            <dataSource type="UNPOOLED">                <property name="driver" value="${driver}"/>                <property name="url" value="${url}"/>                <property name="username" value="${username}"/>                <property name="password" value="${password}"/>            </dataSource>        </environment>    </environments>    <!-- SQL Mapper -->    <mappers>        <mapper resource="org/apache/ibatis/builder/AuthorMapper.xml"/>        <mapper resource="org/apache/ibatis/builder/BlogMapper.xml"/>        <mapper resource="org/apache/ibatis/builder/CachedAuthorMapper.xml"/>        <mapper resource="org/apache/ibatis/builder/PostMapper.xml"/>        <mapper resource="org/apache/ibatis/builder/NestedBlogMapper.xml"/>    </mappers></configuration>

初始化入口从SqlSessionFactoryBuilder.build()方法开始

XMLConfigBuilder parser = new XMLConfigBuilder(reader, environment, properties);return build(parser.parse());

XMLConfigBuilder构造器对构建出了Configuration对象, 并作了一定的初始化动作

public XMLConfigBuilder(InputStream inputStream, String environment, Properties props) {    this(new XPathParser(inputStream, true, props, new XMLMapperEntityResolver()), environment, props);}private XMLConfigBuilder(XPathParser parser, String environment, Properties props) {    // 创建Configuration对象    super(new Configuration());    // 基于ThreadLocal的错误上下文    ErrorContext.instance().resource("SQL Mapper Configuration");    this.configuration.setVariables(props);    this.parsed = false;    this.environment = environment;    // 核心的XML解析器    this.parser = parser;}

在new Configuration()中已经作了部分初始化, 如类别名注册等

public Configuration() {    // 注册事务工厂别名    typeAliasRegistry.registerAlias("JDBC", JdbcTransactionFactory.class);    typeAliasRegistry.registerAlias("MANAGED", ManagedTransactionFactory.class);    // 注册数据源工厂别名    typeAliasRegistry.registerAlias("JNDI", JndiDataSourceFactory.class);    typeAliasRegistry.registerAlias("POOLED", PooledDataSourceFactory.class);    typeAliasRegistry.registerAlias("UNPOOLED", UnpooledDataSourceFactory.class);    // 注册缓存策略别名    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);    // 数据库厂商标识提供者    typeAliasRegistry.registerAlias("DB_VENDOR", VendorDatabaseIdProvider.class);    // 语言解析驱动类    typeAliasRegistry.registerAlias("XML", XMLLanguageDriver.class);    typeAliasRegistry.registerAlias("RAW", RawLanguageDriver.class);    // 注册日志处理类    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);    // 注册动态代理工厂, 基于Cglib或者JAVASSIST    typeAliasRegistry.registerAlias("CGLIB", CglibProxyFactory.class);    typeAliasRegistry.registerAlias("JAVASSIST", JavassistProxyFactory.class);    // 解析动态SQL时用到的语言驱动, 3.2之后插拔自己的语言驱动    languageRegistry.setDefaultDriverClass(XMLLanguageDriver.class);    languageRegistry.register(RawLanguageDriver.class);}

接下来就是parser.parse()核心方法

public Configuration parse() {    if (parsed) {        throw new BuilderException("Each XMLConfigBuilder can only be used once.");    }    parsed = true;    parseConfiguration(parser.evalNode("/configuration"));    return configuration;}private void parseConfiguration(XNode root) {    try {        // 属性        propertiesElement(root.evalNode("properties"));        // 别名        typeAliasesElement(root.evalNode("typeAliases"));        // 插件        pluginElement(root.evalNode("plugins"));        // 对象工厂        objectFactoryElement(root.evalNode("objectFactory"));        // 对象包装器工厂        objectWrapperFactoryElement(root.evalNode("objectWrapperFactory"));        // 设置        settingsElement(root.evalNode("settings"));        // 环境        environmentsElement(root.evalNode("environments")); // read it after objectFactory and objectWrapperFactory issue #631        // 数据库提供商        databaseIdProviderElement(root.evalNode("databaseIdProvider"));        // 类型处理器        typeHandlerElement(root.evalNode("typeHandlers"));        // SQL mapper        mapperElement(root.evalNode("mappers"));    } catch (Exception e) {        throw new BuilderException("Error parsing SQL Mapper Configuration. Cause: " + e, e);    }

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