filterconfig struts2执行流程(3)

跟进buildExcludedPatternsList方法：

public List<Pattern> buildExcludedPatternsList( Dispatcher dispatcher ) {
    // 由此可知是struts2是读取了STRUTS_ACTION_EXCLUDE_PATTERN常量的值来判断哪些请求不需要匹配
    return buildExcludedPatternsList(dispatcher.getContainer().getInstance(String.class, StrutsConstants.STRUTS_ACTION_EXCLUDE_PATTERN));
}

private List<Pattern> buildExcludedPatternsList( String patterns ) {
    if (null != patterns && patterns.trim().length() != 0) {
        List<Pattern> list = new ArrayList<Pattern>();
        String[] tokens = patterns.split(",");
        for ( String token : tokens ) {
            list.add(Pattern.compile(token.trim()));
        }
        return Collections.unmodifiableList(list);
    } else {
        return null;
    }
}

struts2是根据STRUTS_ACTION_EXCLUDE_PATTERN常量的值来判断哪些请求不需要匹配，所以我们如果想要设置某些请求不被struts2匹配就可以设置这个常量struts.action.excludePattern，多个pattern之间用逗号隔开（pattern的写法和web.xml中配置的类似）

prepare.setEncodingAndLocale(request, response)，是由Dispatcher在准备的过程中完成的，源码如下：

/**
 * Sets the request encoding and locale on the response
 * 设置请求和响应的国际化编码
 */
public void setEncodingAndLocale(HttpServletRequest request, HttpServletResponse response) {
    dispatcher.prepare(request, response);
}

跟进prepare方法一看究竟：

/**
 * Prepare a request, including setting the encoding and locale.
 *
 * @param request The request
 * @param response The response
 */
public void prepare(HttpServletRequest request, HttpServletResponse response) {
    String encoding = null;
    if (defaultEncoding != null) {
        encoding = defaultEncoding;
    }
    // check for Ajax request to use UTF-8 encoding strictly http://www.w3.org/TR/XMLHttpRequest/#the-send-method
    if ("XMLHttpRequest".equals(request.getHeader("X-Requested-With"))) {
        encoding = "UTF-8";
    }

    Locale locale = null;
    if (defaultLocale != null) {
        locale = LocalizedTextUtil.localeFromString(defaultLocale, request.getLocale());
    }

    if (encoding != null) {
        applyEncoding(request, encoding);
    }

    if (locale != null) {
        response.setLocale(locale);
    }

    if (paramsWorkaroundEnabled) {
        request.getParameter("foo"); // simply read any parameter (existing or not) to "prime" the request
    }
}

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