使用java的紧凑字符串功能,是否有公共API来获取字符串的实际编码或内存使用?我可以调用包私有方法coder
或私有方法isLatin1
并调整计算,但两者都将导致Illegal reflective access
警告。
Method isLatin1 = String.class.getDeclaredMethod("isLatin1");
isLatin1.setAccessible(true);
System.out.println((boolean)isLatin1.invoke("Jörn"));
System.out.println((boolean)isLatin1.invoke("foobar"));
System.out.println((boolean)isLatin1.invoke("\u03b1"));
使用JOL非常容易(但我不完全确定这是你想要的):
String left = "Jörn";
System.out.println(GraphLayout.parseInstance(left).totalSize()); // 48 bytes
String right = "foobar";
System.out.println(GraphLayout.parseInstance(right).totalSize()); // 48 bytes
String oneMore = "\u03b1";
System.out.println(GraphLayout.parseInstance(oneMore).totalSize()); // 48 bytes
对于编码,没有公共API,但您可以推断它...
private static String encoding(String s) {
char[] arr = s.toCharArray();
for (char c : arr) {
if (c >>> 8 != 0) {
return "UTF16";
}
}
return "Latin1";
}