Digester.java 文件源码

/**
 * Returns an attributes list which contains all the attributes
 * passed in, with any text of form "${xxx}" in an attribute value
 * replaced by the appropriate value from the system property.
 */
private Attributes updateAttributes(Attributes list) {

    if (list.getLength() == 0) {
        return list;
    }

    AttributesImpl newAttrs = new AttributesImpl(list);
    int nAttributes = newAttrs.getLength();
    for (int i = 0; i < nAttributes; ++i) {
        String value = newAttrs.getValue(i);
        try {
            String newValue = 
                IntrospectionUtils.replaceProperties(value, null, source);
            if (value != newValue) {
                newAttrs.setValue(i, newValue);
            }
        }
        catch (Exception e) {
            // ignore - let the attribute have its original value
        }
    }

    return newAttrs;

}