Chapter 2 - Jetty读取配置文件和Loader (2)

编程技术  /  houtizong 发布于 3年前   49

1. XmlConfiguration的value方法

读取某个节点的值，并进行相应处理：修剪空字符串，解析并拼接结果

private Object value(Object obj, XmlParser.Node node) throws Exception    {        Object value = null;        // Get the type        String type = node.getAttribute("type");        // Try a ref lookup        String ref = node.getAttribute("ref");        if (ref != null)        {            value = _idMap.get(ref);        }        else        {            // handle trivial case            if (node.size() == 0)            {                if ("String".equals(type)) return "";                return null;            }            // Trim values            int first = 0;            int last = node.size() - 1;            // Handle default trim type            if (type == null || !"String".equals(type))            {                // Skip leading white                Object item = null;                while (first <= last)                {                    item = node.get(first);                    if (!(item instanceof String)) break;                    item = ((String) item).trim();                    if (((String) item).length() > 0) break;                    first++;                }                // Skip trailing white                while (first < last)                {                    item = node.get(last);                    if (!(item instanceof String)) break;                    item = ((String) item).trim();                    if (((String) item).length() > 0) break;                    last--;                }                // All white, so return null                if (first > last) return null;            }            if (first == last)                //  Single Item value                value = itemValue(obj, node.get(first));            else            {                // Get the multiple items as a single string                StringBuffer buf = new StringBuffer();                synchronized (buf)                {                    for (int i = first; i <= last; i++)                    {                        Object item = node.get(i);                        buf.append(itemValue(obj, item));                    }                    value = buf.toString();                }            }        }        // Untyped or unknown        if (value == null)        {            if ("String".equals(type)) return "";            return null;        }        // Try to type the object        if (type == null)        {            if (value != null && value instanceof String) return ((String) value).trim();            return value;        }        if ("String".equals(type) || "java.lang.String".equals(type)) return value.toString();        Class pClass = TypeUtil.fromName(type);        if (pClass != null) return TypeUtil.valueOf(pClass, value.toString());        if ("URL".equals(type) || "java.net.URL".equals(type))        {            if (value instanceof URL) return value;            try            {                return new URL(value.toString());            }            catch (MalformedURLException e)            {                throw new InvocationTargetException(e);            }        }        if ("InetAddress".equals(type) || "java.net.InetAddress".equals(type))        {            if (value instanceof InetAddress) return value;            try            {                return InetAddress.getByName(value.toString());            }            catch (UnknownHostException e)            {                throw new InvocationTargetException(e);            }        }        throw new IllegalStateException("Unknown type " + type);    }

2. XmlConfiguration的itemValue方法

读取单个节点的值，如果item是String类型，直接返回
如果是其它的tag，还需要调用对应的处理方法

private Object itemValue(Object obj, Object item) throws Exception    {        // String value        if (item instanceof String) return item;        XmlParser.Node node = (XmlParser.Node) item;        String tag = node.getTag();        if ("Call".equals(tag)) return call(obj, node);        if ("Get".equals(tag)) return get(obj, node);        if ("New".equals(tag)) return newObj(obj, node);        if ("Ref".equals(tag)) return refObj(obj, node);        if ("Array".equals(tag)) return newArray(obj, node);        if ("Map".equals(tag)) return newMap(obj, node);        if ("Property".equals(tag)) return propertyObj(obj,node);        if ("SystemProperty".equals(tag))        {            String name = node.getAttribute("name");            String defaultValue = node.getAttribute("default");            return System.getProperty(name, defaultValue);        }                Log.warn("Unknown value tag: " + node, new Throwable());        return null;    }