Java获取随机字符串

import java.util.Random;
public static String getRandomString(int length) {
	StringBuffer buffer = new StringBuffer("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
	StringBuffer sb = new StringBuffer();
	Random r = new Random();
	int range = buffer.length();
	for (int i = 0; i < length; i ++) {
		sb.append(buffer.charAt(r.nextInt(range)));
	}
	return sb.toString();
}