java重构模式匹配序列

Question

我有以下一段代码（示例缩短）：

while (reader.ready()) {
    String line = reader.readLine();

    Matcher responseCodeMatcher = responseCodePattern.matcher(line); 
    if (responseCodeMatcher.matches()) {
        responseCode = Integer.parseInt(responseCodeMatcher.group(1));
        continue;
    }

    Matcher cacheControlMatcher = cacheControlPattern.matcher(line); 
    if (cacheControlMatcher.matches()) {
        cacheControl = CacheControl.parseString(responseCodeMatcher.group(1));
        continue;
    }

        ...

}

这些模式都是该类的静态最终成员。 所以我有一系列的模式，我想找出每一行是否匹配其中一个，如果匹配，做点什么（从一个模式到另一个模式）。你能想出一个方法来很好地重构它吗？也许是我看过的一系列模式（如果匹配，我怎么知道该怎么做？）或者其他想法

Answer 1

我最终以以下方式进行重构。我创建了一个类HttpPatterns：

package cs236369.proxy.types;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public enum HttpPatterns {
    RESPONSE_CODE("^HTTP/1\\.1 (\\d+) .*$"),
    CACHE_CONTROL("^Cache-Control: (\\w+)$"),
    HOST("^Host: (\\w+)$"),
    REQUEST_HEADER("(GET|POST) ([^\\s]+) ([^\\s]+)$"),
    ACCEPT_ENCODING("^Accept-Encoding: .*$"),
    CONTENT_ENCODING("^Content-Encoding: ([^\\s]+)$");

    private final Pattern pattern;

    HttpPatterns(String regex) {
        pattern = Pattern.compile(regex);
    }

    public boolean matches(String expression) {
        return pattern.matcher(expression).matches();
    }

    public Object process(String expression) {
        Matcher matcher = pattern.matcher(expression);
        if (!matcher.matches()) {
            throw new RuntimeException("Called `process`, but the expression doesn't match. Call `matches` first.");
        }

        if (this == RESPONSE_CODE) {
            return Integer.parseInt(matcher.group(1));
        } else if (this == CACHE_CONTROL) {
            return CacheControl.parseString(matcher.group(1));
        } else if (this == HOST) {
            return matcher.group(1);
        } else if (this == REQUEST_HEADER) {
            return new RequestHeader(RequestType.parseString(matcher.group(1)), matcher.group(2), matcher.group(3));
        } else if (this == CONTENT_ENCODING) {
            return ContentEncoding.parseString(matcher.group(1));
        } else { //never happens
            return null;
        }
    }


}

我这样使用它：

String line;
            while ((line = reader.readLine()) != null) {

                if (HttpPatterns.CACHE_CONTROL.matches(line)) {
                    cacheControl = (CacheControl) HttpPatterns.RESPONSE_CODE.process(line);
                } else if (HttpPatterns.REQUEST_HEADER.matches(line)) {
                    requestHeader = (RequestHeader) HttpPatterns.REQUEST_HEADER.process(line);
                } else if (HttpPatterns.HOST.matches(line)) {
                    requestHost = (String) HttpPatterns.HOST.process(line);
                } else if (HttpPatterns.ACCEPT_ENCODING.matches(line)) {
                    continue;
                } else if (line.isEmpty()) {
                    break;
                }
                fullRequest += "\r\n" + line;
            }

我不喜欢这样，我必须把我得到的一切都投进去，但这是迄今为止我找到的最好的解决方案