servlet匹配過程核心代碼

一個http請求 如何匹配到具體的servlet

package org.apache.catalina.mapper;

public final class Mapper {
 /**
     * Extension mappings.
     *
     * @param wrappers          Set of wrappers to check for matches
     * @param path              Path to map
     * @param mappingData       Mapping data for result
     * @param resourceExpected  Is this mapping expecting to find a resource
     */
    private final void internalMapExtensionWrapper(MappedWrapper[] wrappers,
            CharChunk path, MappingData mappingData, boolean resourceExpected) {
        char[] buf = path.getBuffer();
        int pathEnd = path.getEnd();
        int servletPath = path.getOffset();
        int slash = -1;
        for (int i = pathEnd - 1; i >= servletPath; i--) {
            if (buf[i] == '/') {
                slash = i;
                break;
            }
        }
        if (slash >= 0) {
            int period = -1;
            for (int i = pathEnd - 1; i > slash; i--) {
                if (buf[i] == '.') {
                    period = i;
                    break;
                }
            }
            if (period >= 0) {
                path.setOffset(period + 1);
                path.setEnd(pathEnd);
                MappedWrapper wrapper = exactFind(wrappers, path);
                if (wrapper != null
                        && (resourceExpected || !wrapper.resourceOnly)) {
                    mappingData.wrapperPath.setChars(buf, servletPath, pathEnd
                            - servletPath);
                    mappingData.requestPath.setChars(buf, servletPath, pathEnd
                            - servletPath);
                    mappingData.wrapper = wrapper.object;
                    mappingData.matchType = MappingMatch.EXTENSION;
                }
                path.setOffset(servletPath);
                path.setEnd(pathEnd);
            }
        }
    }