Mybatis3源码笔记（五）mapperElement

1.四种解析mapper方式 : package,resource,url,class。

  <mappers>

    <mapper resource="org/apache/ibatis/builder/BlogMapper.xml"/>

    <mapper url="file:./src/test/java/org/apache/ibatis/builder/NestedBlogMapper.xml"/>

    <mapper class="org.apache.ibatis.builder.CachedAuthorMapper"/>

    <package name="org.apache.ibatis.builder.mapper"/>

  </mappers>

private void mapperElement(XNode parent) throws Exception {

    if (parent != null) {

      for (XNode child : parent.getChildren()) {

        //package引入

        if ("package".equals(child.getName())) {

          String mapperPackage = child.getStringAttribute("name");

          configuration.addMappers(mapperPackage);

        } else {

          String resource = child.getStringAttribute("resource");

          String url = child.getStringAttribute("url");

          String mapperClass = child.getStringAttribute("class");

          //resource引入

          if (resource != null && url == null && mapperClass == null) {

            ErrorContext.instance().resource(resource);

            try (InputStream inputStream = Resources.getResourceAsStream(resource)) {

              XMLMapperBuilder mapperParser = new XMLMapperBuilder(inputStream, configuration, resource, configuration.getSqlFragments());

              mapperParser.parse();

            }

          } else if (resource == null && url != null && mapperClass == null) {

            //url引入

            ErrorContext.instance().resource(url);

            try (InputStream inputStream = Resources.getUrlAsStream(url)) {

              XMLMapperBuilder mapperParser = new XMLMapperBuilder(inputStream, configuration, url, configuration.getSqlFragments());

              mapperParser.parse();

            }

          } else if (resource == null && url == null && mapperClass != null) {

            //mapperClass引入

            Class<?> mapperInterface = Resources.classForName(mapperClass);

            configuration.addMapper(mapperInterface);

          } else {

            throw new BuilderException("A mapper element may only specify a url, resource or class, but not more than one.");

          }

        }

      }

    }

  }

2.跟一下package引入。

  public <T> void addMapper(Class<T> type) {

    //必须是接口

    if (type.isInterface()) {

      //重复性检查

      if (hasMapper(type)) {

        throw new BindingException("Type " + type + " is already known to the MapperRegistry.");

      }

      boolean loadCompleted = false;

      try {

        knownMappers.put(type, new MapperProxyFactory<>(type));

        //解析Mapper接口

        MapperAnnotationBuilder parser = new MapperAnnotationBuilder(config, type);

        parser.parse();

        loadCompleted = true;

      } finally {

        if (!loadCompleted) {

          knownMappers.remove(type);

        }

      }

    }

  }

  public void parse() {

    String resource = type.toString();

    //判断该resource有没有引入

    if (!configuration.isResourceLoaded(resource)) {

      //加载该命名空间下对应的xml

      loadXmlResource();

      configuration.addLoadedResource(resource);

      assistant.setCurrentNamespace(type.getName());

      //解析二级缓存注解CacheNamespace

      parseCache();

      //解析二级缓存注解CacheNamespaceRef

      parseCacheRef();

      for (Method method : type.getMethods()) {

        //检查下method类型，不能是桥接方法和接口中的默认方法

        if (!canHaveStatement(method)) {

          continue;

        }

        //select操作解析@select,@SelectProvider注释方法中的带有@ResultMap的方法

        if (getAnnotationWrapper(method, false, Select.class, SelectProvider.class).isPresent()

            && method.getAnnotation(ResultMap.class) == null) {

          parseResultMap(method);

        }

        try {

          //解析Statement

          parseStatement(method);

        } catch (IncompleteElementException e) {

          configuration.addIncompleteMethod(new MethodResolver(this, method));

        }

      }

    }

    //解析IncompleteMethod，解析失败的方法。

    parsePendingMethods();

  }

 void parseStatement(Method method) {

     //取得方法的参数类型

    final Class<?> parameterTypeClass = getParameterType(method);

    //根据@Lang取得方法的LanguageDriver,默认是XMLLanguageDriver

    final LanguageDriver languageDriver = getLanguageDriver(method);

    //解析所有合法的statement注解，譬如@Select, @Update, @Insert, @Delete, @SelectProvider...

    getAnnotationWrapper(method, true, statementAnnotationTypes).ifPresent(statementAnnotation -> {

      //生成SqlSource

      final SqlSource sqlSource = buildSqlSource(statementAnnotation.getAnnotation(), parameterTypeClass, languageDriver, method);

      final SqlCommandType sqlCommandType = statementAnnotation.getSqlCommandType();

      //取得@Options注解

      final Options options = getAnnotationWrapper(method, false, Options.class).map(x -> (Options) x.getAnnotation()).orElse(null);

      //设置mappedStatementId，方法的全路径

      final String mappedStatementId = type.getName() + "." + method.getName();

      final KeyGenerator keyGenerator;

      String keyProperty = null;

      String keyColumn = null;

      //插入和更新需要涉及到主键自动生成

      if (SqlCommandType.INSERT.equals(sqlCommandType) || SqlCommandType.UPDATE.equals(sqlCommandType)) {

        // @SelectKey注解生成主键

        SelectKey selectKey = getAnnotationWrapper(method, false, SelectKey.class).map(x -> (SelectKey) x.getAnnotation()).orElse(null);

        if (selectKey != null) {

          keyGenerator = handleSelectKeyAnnotation(selectKey, mappedStatementId, getParameterType(method), languageDriver);

          keyProperty = selectKey.keyProperty();

        } else if (options == null) {

          //默认模式

          keyGenerator = configuration.isUseGeneratedKeys() ? Jdbc3KeyGenerator.INSTANCE : NoKeyGenerator.INSTANCE;

        } else {

          //根据@Options中的value值实现自定义设置

          keyGenerator = options.useGeneratedKeys() ? Jdbc3KeyGenerator.INSTANCE : NoKeyGenerator.INSTANCE;

          keyProperty = options.keyProperty();

          keyColumn = options.keyColumn();

        }

      } else {

        keyGenerator = NoKeyGenerator.INSTANCE;

      }

      Integer fetchSize = null;

      Integer timeout = null;

      StatementType statementType = StatementType.PREPARED;

      ResultSetType resultSetType = configuration.getDefaultResultSetType();

      boolean isSelect = sqlCommandType == SqlCommandType.SELECT;

      boolean flushCache = !isSelect;

      boolean useCache = isSelect;

      if (options != null) {

        //设置对应的options

        if (FlushCachePolicy.TRUE.equals(options.flushCache())) {

          flushCache = true;

        } else if (FlushCachePolicy.FALSE.equals(options.flushCache())) {

          flushCache = false;

        }

        useCache = options.useCache();

        fetchSize = options.fetchSize() > -1 || options.fetchSize() == Integer.MIN_VALUE ? options.fetchSize() : null; //issue #348

        timeout = options.timeout() > -1 ? options.timeout() : null;

        statementType = options.statementType();

        if (options.resultSetType() != ResultSetType.DEFAULT) {

          resultSetType = options.resultSetType();

        }

      }

      String resultMapId = null;

      if (isSelect) {

        ResultMap resultMapAnnotation = method.getAnnotation(ResultMap.class);

        if (resultMapAnnotation != null) {

          //根据 @ResultMap({ "xx", "xxx" })设置resultMapId

          resultMapId = String.join(",", resultMapAnnotation.value());

        } else {

          //没配置@ResultMap则走generateResultMapName方法生成resultMapId（方法的详细路径+“-”+参数类型）

          resultMapId = generateResultMapName(method);

        }

      }

      //生成Statement`

      assistant.addMappedStatement(

        mappedStatementId,

        sqlSource,

        statementType,

        sqlCommandType,

        fetchSize,

        timeout,

        // ParameterMapID

        null,

        parameterTypeClass,

        resultMapId,

        getReturnType(method),

        resultSetType,

        flushCache,

        useCache,

        // TODO gcode issue #577

        false,

        keyGenerator,

        keyProperty,

        keyColumn,

        statementAnnotation.getDatabaseId(),

        languageDriver,

        // ResultSets

        options != null ? nullOrEmpty(options.resultSets()) : null);

    });

  }

3.其它的引入方式resource和url方式，就是先解析一波xml文件，大同小异。

  public void parse() {

    if (!configuration.isResourceLoaded(resource)) {

      //解析mapper.xml文件

      configurationElement(parser.evalNode("/mapper"));

      configuration.addLoadedResource(resource);

      //解析对应空间下的mapper接口（跟上面的package方法一样的解析过程）

      bindMapperForNamespace();

    }

    parsePendingResultMaps();

    parsePendingCacheRefs();

    parsePendingStatements();

  }

  private void configurationElement(XNode context) {

    try {

      String namespace = context.getStringAttribute("namespace");

      if (namespace == null || namespace.isEmpty()) {

        throw new BuilderException("Mapper's namespace cannot be empty");

      }

      //设置命名空间

      builderAssistant.setCurrentNamespace(namespace);

      //设置二级缓存

      cacheRefElement(context.evalNode("cache-ref"));

      cacheElement(context.evalNode("cache"));

      //解析parameterMap

      parameterMapElement(context.evalNodes("/mapper/parameterMap"));

      //解析resultMap

      resultMapElements(context.evalNodes("/mapper/resultMap"));

      //解析sql片段

      sqlElement(context.evalNodes("/mapper/sql"));

      //解析真正的sql语句

      buildStatementFromContext(context.evalNodes("select|insert|update|delete"));

    } catch (Exception e) {

      throw new BuilderException("Error parsing Mapper XML. The XML location is '" + resource + "'. Cause: " + e, e);

    }

  }

巴特西

Mybatis3源码笔记（五）mapperElement

1.四种解析mapper方式 : package,resource,url,class。

2.跟一下package引入。

3.其它的引入方式resource和url方式，就是先解析一波xml文件，大同小异。

mapper的解析分注解如@Select和xml两种解析，看代码我们可以看出来，同一个方法都是先找xml，后分析注解，根据`configuration.isResourceLoaded`来判断是否已经解析，防止重复解析。

最新文章

热门文章

巴特西

Mybatis3源码笔记（五）mapperElement

1.四种解析mapper方式 : package,resource,url,class。

2.跟一下package引入。

3.其它的引入方式resource和url方式，就是先解析一波xml文件，大同小异。

mapper的解析分注解如@Select和xml两种解析，看代码我们可以看出来，同一个方法都是先找xml，后分析注解，根据configuration.isResourceLoaded来判断是否已经解析，防止重复解析。

最新文章

热门文章

mapper的解析分注解如@Select和xml两种解析，看代码我们可以看出来，同一个方法都是先找xml，后分析注解，根据`configuration.isResourceLoaded`来判断是否已经解析，防止重复解析。