MyBatis3 源码解析 (7)TypeHandler 注册与获取

  configuration.getTypeHandlerRegistry().register(String[].class, JdbcType.VARCHAR, StringArrayTypeHandler.class);
  private void register(Type javaType, JdbcType jdbcType, TypeHandler<?> handler) {    if (javaType != null) {      Map<JdbcType, TypeHandler<?>> map = typeHandlerMap.get(javaType);      if (map == null || map == NULL_TYPE_HANDLER_MAP) {        map = new HashMap<>();      }      map.put(jdbcType, handler);      typeHandlerMap.put(javaType, map);    }    allTypeHandlersMap.put(handler.getClass(), handler);  }

  public <T> void addMapper(Class<T> type) {    if (type.isInterface()) {      if (hasMapper(type)) {        throw new BindingException("Type " + type + " is already known to the MapperRegistry.");      }      boolean loadCompleted = false;      try {        // 生成我们熟悉的Mapper代理类        knownMappers.put(type, new MapperProxyFactory<>(type));        // It's important that the type is added before the parser is run        // otherwise the binding may automatically be attempted by the        // mapper parser. If the type is already known, it won't try.        MapperAnnotationBuilder parser = new MapperAnnotationBuilder(config, type);  // 进行解析        parser.parse();        loadCompleted = true;      } finally {        if (!loadCompleted) {          knownMappers.remove(type);        }      }    }  }

  void parseStatement(Method method) {    ......    getAnnotationWrapper(method, true, statementAnnotationTypes).ifPresent(statementAnnotation -> {      final SqlSource sqlSource = buildSqlSource(statementAnnotation.getAnnotation(), parameterTypeClass, languageDriver, method);      ......    });  }
  public SqlSource createSqlSource(Configuration configuration, String script, Class<?> parameterType) {    // issue #3    if (script.startsWith("<script>")) {      XPathParser parser = new XPathParser(script, false, configuration.getVariables(), new XMLMapperEntityResolver());      return createSqlSource(configuration, parser.evalNode("/script"), parameterType);    } else {      // issue #127      script = PropertyParser.parse(script, configuration.getVariables());      TextSqlNode textSqlNode = new TextSqlNode(script);      if (textSqlNode.isDynamic()) {  // 这个暂时不理解        return new DynamicSqlSource(configuration, textSqlNode);      } else {  // 目前走的这个        return new RawSqlSource(configuration, script, parameterType);      }    }  }
  public SqlSource parse(String originalSql, Class<?> parameterType, Map<String, Object> additionalParameters) {    ParameterMappingTokenHandler handler = new ParameterMappingTokenHandler(configuration, parameterType, additionalParameters);    GenericTokenParser parser = new GenericTokenParser("#{", "}", handler);    String sql;    if (configuration.isShrinkWhitespacesInSql()) {      sql = parser.parse(removeExtraWhitespaces(originalSql));    } else {      // 走的这个      sql = parser.parse(originalSql);    }    return new StaticSqlSource(configuration, sql, handler.getParameterMappings());  }

public class GenericTokenParser {  public String parse(String text) {    if (text == null || text.isEmpty()) {      return "";    }    // search open token    int start = text.indexOf(openToken);    if (start == -1) {      return text;    }    char[] src = text.toCharArray();    int offset = 0;    final StringBuilder builder = new StringBuilder();    StringBuilder expression = null;    do {      if (start > 0 && src[start - 1] == '\\') {        // this open token is escaped. remove the backslash and continue.        builder.append(src, offset, start - offset - 1).append(openToken);        offset = start + openToken.length();      } else {        // found open token. let's search close token.        if (expression == null) {          expression = new StringBuilder();        } else {          expression.setLength(0);        }        builder.append(src, offset, start - offset);        offset = start + openToken.length();        int end = text.indexOf(closeToken, offset);        while (end > -1) {          if (end > offset && src[end - 1] == '\\') {            // this close token is escaped. remove the backslash and continue.            expression.append(src, offset, end - offset - 1).append(closeToken);            offset = end + closeToken.length();            end = text.indexOf(closeToken, offset);          } else {            expression.append(src, offset, end - offset);            break;          }        }        if (end == -1) {          // close token was not found.          builder.append(src, start, src.length - start);          offset = src.length;        } else {          builder.append(handler.handleToken(expression.toString()));          offset = end + closeToken.length();        }      }      start = text.indexOf(openToken, offset);    } while (start > -1);    if (offset < src.length) {      builder.append(src, offset, src.length - offset);    }    return builder.toString();  }}

    public String handleToken(String content) {      parameterMappings.add(buildParameterMapping(content));      return "?";    }
    // 在其中设置JavaType和jdbcType    private ParameterMapping buildParameterMapping(String content) {      Map<String, String> propertiesMap = parseParameterMapping(content);      String property = propertiesMap.get("property");      Class<?> propertyType;      if (metaParameters.hasGetter(property)) { // issue #448 get type from additional params        propertyType = metaParameters.getGetterType(property);      } else if (typeHandlerRegistry.hasTypeHandler(parameterType)) {        propertyType = parameterType;      } else if (JdbcType.CURSOR.name().equals(propertiesMap.get("jdbcType"))) {        propertyType = java.sql.ResultSet.class;      } else if (property == null || Map.class.isAssignableFrom(parameterType)) {        propertyType = Object.class;      } else {        MetaClass metaClass = MetaClass.forClass(parameterType, configuration.getReflectorFactory());        if (metaClass.hasGetter(property)) {          propertyType = metaClass.getGetterType(property);        } else {          propertyType = Object.class;        }      }      ParameterMapping.Builder builder = new ParameterMapping.Builder(configuration, property, propertyType);      Class<?> javaType = propertyType;      String typeHandlerAlias = null;      for (Map.Entry<String, String> entry : propertiesMap.entrySet()) {        String name = entry.getKey();        String value = entry.getValue();        if ("javaType".equals(name)) {          javaType = resolveClass(value);          builder.javaType(javaType);        } else if ("jdbcType".equals(name)) {          builder.jdbcType(resolveJdbcType(value));        } else if ("mode".equals(name)) {          builder.mode(resolveParameterMode(value));        } else if ("numericScale".equals(name)) {          builder.numericScale(Integer.valueOf(value));        } else if ("resultMap".equals(name)) {          builder.resultMapId(value);        } else if ("typeHandler".equals(name)) {          typeHandlerAlias = value;        } else if ("jdbcTypeName".equals(name)) {          builder.jdbcTypeName(value);        } else if ("property".equals(name)) {          // Do Nothing        } else if ("expression".equals(name)) {          throw new BuilderException("Expression based parameters are not supported yet");        } else {          throw new BuilderException("An invalid property '" + name + "' was found in mapping #{" + content + "}.  Valid properties are " + PARAMETER_PROPERTIES);        }      }      if (typeHandlerAlias != null) {        builder.typeHandler(resolveTypeHandler(javaType, typeHandlerAlias));      }      return builder.build();    }
    public ParameterMapping build() {      resolveTypeHandler();      validate();      return parameterMapping;    }
    private void resolveTypeHandler() {      if (parameterMapping.typeHandler == null && parameterMapping.javaType != null) {        Configuration configuration = parameterMapping.configuration;        TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();  // 从Map中获取对应的TypeHandler，以javaType和jdbcType为标识        parameterMapping.typeHandler = typeHandlerRegistry.getTypeHandler(parameterMapping.javaType, parameterMapping.jdbcType);      }    }
  private <T> TypeHandler<T> getTypeHandler(Type type, JdbcType jdbcType) {    if (ParamMap.class.equals(type)) {      return null;    }    // 根据javaType获取Map    Map<JdbcType, TypeHandler<?>> jdbcHandlerMap = getJdbcHandlerMap(type);    TypeHandler<?> handler = null;    if (jdbcHandlerMap != null) {      // 根据jdbcType获取      handler = jdbcHandlerMap.get(jdbcType);      if (handler == null) {        handler = jdbcHandlerMap.get(null);      }      if (handler == null) {        // #591        handler = pickSoleHandler(jdbcHandlerMap);      }    }    // type drives generics here    return (TypeHandler<T>) handler;  }