Record some commonly used java code

1. Get the current time of the system:

Because there are many operations with a large amount of data, it is necessary to record the usage time. I usually write something myself. After all, I have been browsing the blog for so long. I have never posted an article.

Date sysTime = new Date();
SimpleDateFormat sdf = new SimpleDateFormat('yyyy-MM-dd HH:mm:ss');
sdf.format (sysTime);

Remember one thing. Most of the time is recorded at the beginning and end of the code. So when you need a new date at the beginning of the recording time and a new one at the end

2. Randomly output a string based on the given string

public static String getRandomString(int length){
    String str = "1234567890qwertyuiopasdfghjklzxcvbnmWGJB";
    Random random = new Random();
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < length; i++){
        int number = random.nextInt(length);
        sb.append(str.charAt(number));
    }
    return sb.toString();
}