Spring Utils工具类常用方法实例

spring提供的工具类，主要用于框架内部使用，这个类提供了一些简单的方法，并且提供了易于使用的方法在分割字符串，如csv字符串，以及集合和数组。

stringutils提供常用的方法如下：

判断对象对象是否为null或者空字符串

public static boolean isempty(@nullable object str) {
	return (str == null || "".equals(str));
}

判断给的序列是否为空或者length为0

public static boolean haslength(@nullable charsequence str) {
	return (str != null && str.length() > 0);
}

	public static boolean haslength(@nullable string str) {
		return (str != null && !str.isempty());
	}

判断字符串是否以某个字符串开头

public static boolean startswithignorecase(@nullable string str, @nullable string prefix) {
	return (str != null && prefix != null && str.length() >= prefix.length() &&
			str.regionmatches(true, 0, prefix, 0, prefix.length()));
}

判断字符串是否以某个字符串结尾

public static boolean endswithignorecase(@nullable string str, @nullable string suffix) {
	return (str != null && suffix != null && str.length() >= suffix.length() &&
			str.regionmatches(true, str.length() - suffix.length(), suffix, 0, suffix.length()));
}

用另一个字符串替换字符串中出现的所有子字符串

public static string replace(string instring, string oldpattern, @nullable string newpattern) {
		if (!haslength(instring) || !haslength(oldpattern) || newpattern == null) {
			return instring;
		}
		//oldpattern字符串第一次出现的位置
		int index = instring.indexof(oldpattern);
		if (index == -1) {
			// no occurrence -> can return input as-is
			return instring;
		}
		//字符串长度
	int capacity = instring.length();
	if (newpattern.length() > oldpattern.length()) {
		capacity += 16;
	}
	stringbuilder sb = new stringbuilder(capacity);

	int pos = 0; // our position in the old string
	int patlen = oldpattern.length();
	while (index >= 0) {
		sb.append(instring, pos, index);
		sb.append(newpattern);
		pos = index + patlen;
		index = instring.indexof(oldpattern, pos);
	}

	// append any characters to the right of a match
	sb.append(instring, pos, instring.length());
	return sb.tostring();
}

根据给定的路径规范化路径

public static string cleanpath(string path) {
		if (!haslength(path)) {
			return path;
		}
  //用新字符串替换旧字符串
	string pathtouse = replace(path, windows_folder_separator, folder_separator);
	// shortcut if there is no work to do
	if (pathtouse.indexof('.') == -1) {
		return pathtouse;
	}

	// strip prefix from path to analyze, to not treat it as part of the
	// first path element. this is necessary to correctly parse paths like
	// "file:core/../core/io/resource.class", where the ".." should just
	// strip the first "core" directory while keeping the "file:" prefix.
	int prefixindex = pathtouse.indexof(':');
	string prefix = "";
	if (prefixindex != -1) {
		prefix = pathtouse.substring(0, prefixindex + 1);
		if (prefix.contains(folder_separator)) {
			prefix = "";
		}
		else {
			pathtouse = pathtouse.substring(prefixindex + 1);
		}
	}
	if (pathtouse.startswith(folder_separator)) {
		prefix = prefix + folder_separator;
		pathtouse = pathtouse.substring(1);
	}

	string[] patharray = delimitedlisttostringarray(pathtouse, folder_separator);
	linkedlist<string> pathelements = new linkedlist<>();
	int tops = 0;

	for (int i = patharray.length - 1; i >= 0; i--) {
		string element = patharray[i];
		if (current_path.equals(element)) {
			// points to current directory - drop it.
		}
		else if (top_path.equals(element)) {
			// registering top path found.
			tops++;
		}
		else {
			if (tops > 0) {
				// merging path element with element corresponding to top path.
				tops--;
			}
			else {
				// normal path element found.
				pathelements.add(0, element);
			}
		}
	}

	// remaining top paths need to be retained.
	for (int i = 0; i < tops; i++) {
		pathelements.add(0, top_path);
	}
	// if nothing else left, at least explicitly point to current path.
	if (pathelements.size() == 1 && "".equals(pathelements.getlast()) && !prefix.endswith(folder_separator)) {
		pathelements.add(0, current_path);
	}

	return prefix + collectiontodelimitedstring(pathelements, folder_separator);
}

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