XpathUtils.java 文件源码

/**
 * Used to optimize performance by avoiding expensive file access every time
 * a DTMManager is constructed as a result of constructing a Xalan xpath
 * context!
 */
private static void speedUpDtmManager() throws Exception {
    // https://github.com/aws/aws-sdk-java/issues/238
    // http://stackoverflow.com/questions/6340802/java-xpath-apache-jaxp-implementation-performance
    // CHECKSTYLE:OFF - We need to load system properties from third-party libraries.
    if (System.getProperty(DTM_MANAGER_DEFAULT_PROP_NAME) == null) {
        // CHECKSTYLE:ON
        Class<?> xPathContextClass = Class.forName(XPATH_CONTEXT_CLASS_NAME);
        Method getDtmManager = xPathContextClass.getMethod("getDTMManager");
        Object xPathContext = xPathContextClass.newInstance();
        Object dtmManager = getDtmManager.invoke(xPathContext);

        if (DTM_MANAGER_IMPL_CLASS_NAME.equals(dtmManager.getClass().getName())) {
            // This would avoid the file system to be accessed every time
            // the internal XPathContext is instantiated.
            System.setProperty(DTM_MANAGER_DEFAULT_PROP_NAME,
                               DTM_MANAGER_IMPL_CLASS_NAME);
        }
    }
}