Nicksxs's Blog

class Solution {
    Map<String, Integer> counter = new HashMap<>();
    public int lengthOfLongestSubstring(String s) {
        int length = s.length();
        // 当前的长度
        int subStringLength = 0;
        // 最长的长度
        int maxSubStringLength = 0;
        // 考虑到重复的位置已经被跳过的情况，即已经在当前长度的字符串范围之前的重复字符不需要回溯
        int lastDuplicatePos = -1;
        for (int i = 0; i < length; i++) {
            // 使用 map 存储字符和上一次出现的位置，如果存在并且大于上一次重复位置
            if (counter.get(String.valueOf(s.charAt(i))) != null && counter.get(String.valueOf(s.charAt(i))) > lastDuplicatePos) {
                // 记录重复位置
                lastDuplicatePos = counter.get(String.valueOf(s.charAt(i)));
                // 重置不重复子串的长度，减去重复起点
                subStringLength = i - counter.get(String.valueOf(s.charAt(i))) - 1;
                // 替换当前位置
                counter.replace(String.valueOf(s.charAt(i)), i);
            } else {
                // 如果不存在就直接 put
                counter.put(String.valueOf(s.charAt(i)), i);
            }
            // 长度累加
            subStringLength++;
            if (subStringLength > maxSubStringLength) {
                // 简单替换
                maxSubStringLength = subStringLength;
            }
        }
        return maxSubStringLength;
    }
}

// org.apache.ibatis.scripting.xmltags.XMLScriptBuilder#parseScriptNode
public SqlSource parseScriptNode() {
    MixedSqlNode rootSqlNode = parseDynamicTags(context);
    SqlSource sqlSource;
    if (isDynamic) {
      sqlSource = new DynamicSqlSource(configuration, rootSqlNode);
    } else {
      sqlSource = new RawSqlSource(configuration, rootSqlNode, parameterType);
    }
    return sqlSource;
  }
// org.apache.ibatis.scripting.xmltags.XMLScriptBuilder#parseDynamicTags
protected MixedSqlNode parseDynamicTags(XNode node) {
    List<SqlNode> contents = new ArrayList<>();
    NodeList children = node.getNode().getChildNodes();
    for (int i = 0; i < children.getLength(); i++) {
      XNode child = node.newXNode(children.item(i));
      if (child.getNode().getNodeType() == Node.CDATA_SECTION_NODE || child.getNode().getNodeType() == Node.TEXT_NODE) {
        String data = child.getStringBody("");
        TextSqlNode textSqlNode = new TextSqlNode(data);
        if (textSqlNode.isDynamic()) {
          contents.add(textSqlNode);
          isDynamic = true;
        } else {
          contents.add(new StaticTextSqlNode(data));
        }
      } else if (child.getNode().getNodeType() == Node.ELEMENT_NODE) { // issue #628
        String nodeName = child.getNode().getNodeName();
        NodeHandler handler = nodeHandlerMap.get(nodeName);
        if (handler == null) {
          throw new BuilderException("Unknown element <" + nodeName + "> in SQL statement.");
        }
        handler.handleNode(child, contents);
        isDynamic = true;
      }
    }
    return new MixedSqlNode(contents);
  }
// org.apache.ibatis.scripting.xmltags.TextSqlNode#isDynamic
  public boolean isDynamic() {
    DynamicCheckerTokenParser checker = new DynamicCheckerTokenParser();
    GenericTokenParser parser = createParser(checker);
    parser.parse(text);
    return checker.isDynamic();
  }
    private GenericTokenParser createParser(TokenHandler handler) {
    return new GenericTokenParser("${", "}", handler);
  }

// org.apache.ibatis.scripting.xmltags.DynamicSqlSource
public class DynamicSqlSource implements SqlSource {

  private final Configuration configuration;
  private final SqlNode rootSqlNode;

  public DynamicSqlSource(Configuration configuration, SqlNode rootSqlNode) {
    this.configuration = configuration;
    this.rootSqlNode = rootSqlNode;
  }

  @Override
  public BoundSql getBoundSql(Object parameterObject) {
    DynamicContext context = new DynamicContext(configuration, parameterObject);
    rootSqlNode.apply(context);
    SqlSourceBuilder sqlSourceParser = new SqlSourceBuilder(configuration);
    Class<?> parameterType = parameterObject == null ? Object.class : parameterObject.getClass();
    SqlSource sqlSource = sqlSourceParser.parse(context.getSql(), parameterType, context.getBindings());
    BoundSql boundSql = sqlSource.getBoundSql(parameterObject);
    context.getBindings().forEach(boundSql::setAdditionalParameter);
    return boundSql;
  }

}