ylbtech-jsp-runoob:jsp Date Processing |
1. JSPDate Processing
one of the most important advantages of using JSP is that you can use all of the Java APIs. This chapter will describe in detail the date class in Java, which, under the Java.util package, encapsulates the current date and time.
The date class has two constructors. The first constructor initializes an object with the current date and time .
Date()
The second constructor takes a parameter that represents the number of milliseconds from midnight January 1, 1970 to the time that you want to represent .
Date(long millisec)
After you get the Date object, you are able to use all the methods listed in the following table:
Serial Number |
method & Description |
1 |
Boolean after (date date) Returns true if it is later than the given date, otherwise false |
2 |
Boolean before (date date) Returns true if it is earlier than the given date, otherwise false |
3 |
Object Clone () Gets a copy of the current object |
4 |
int CompareTo (date date) Returns 0 if it is equalto a given date, returns a negative number if it is earlier than the given day, and returns a positive number if it is later than the given period |
5 |
int compareTo (Object obj) Same as the CompareTo (date) method, throws a ClassCastException exception if obj is not an object of the date class or its subclasses |
6 |
Boolean equals (Object date) Returns true if it is the same as the given date, otherwise false |
7 |
Long GetTime () Returns the number of milliseconds from the early morning of January 1, 1970 to the time represented by the object |
8 |
int Hashcode () Returns the hash code for this object |
9 |
void SetTime (long time) Sets the time and date with the given parameters, which indicates the number of milliseconds elapsed from the wee hours of January 1, 1970 to |
10 |
String toString () Converts this object to a string and returns the string |
Get the current date and time
Using JSP programming makes it easy to get the current date and time, as long as the ToString () method of the Date object is used, as follows:
<%@ Page Language="Java"ContentType="text/html; Charset=utf-8"pageencoding="UTF-8"%><%@ Page Import="java.io.*,java.util.*, javax.servlet.*" %><HTML><Head><title>Show current time and date</title></Head><Body><H1>Show current time and date</H1><% Date Date = New Date(); Out.print (""Center\">" +Date. toString ()+"");%></Body></HTML>
Save the above code in the main.jsp file, and then access the http://localhost:8080/testjsp/main.jsp, running the result as follows:
Show current time and date SatJune: si:
By refreshing http://localhost:8080/testjsp/main.jsp, you can see that the number of seconds each refresh will be different.
Date comparison
As I mentioned at the beginning, you can use any Java method in a JSP script. If you want to compare two dates,
You can do this by referring to the following methods:
- Use the GetTime () method to get the number of milliseconds and then compare the number of milliseconds.
- Use the Before (), after (), Equals () method. For example, new Date (99,2,12). Before (new Date (99,2,18)) returns True.
- Using the CompareTo () method, this method is defined in the comparable interface and implemented in date.
Format dates with SimpleDateFormat
SimpleDateFormat uses a locale-sensitive way to format and parse dates, which allows you to format dates and times using a custom pattern.
Make a slight change to currentdate.jsp and get the following modified code:
<%@ Page Language="Java"ContentType="text/html; Charset=utf-8"pageencoding="UTF-8"%><%@ Page Import="java.io.*,java.util.*" %><%@ Page Import="javax.servlet.*,java.text.*" %><HTML><Head><title>Show current time and date</title></Head><Body><H1>Show current time and date</H1><% DateDnow= New Date( ); SimpleDateFormat ft= NewSimpleDateFormat ("YYYY-MM-DD HH:mm:ss"); Out.print (""Center\">" +Ft.format (Dnow)+ "");%></Body></HTML>
Compiling main.jsp again, and then accessing http://localhost:8080/testjsp/main.jsp, you can get the following results:
Show current time and date : £ º
SimpleDateFormat Format Code
To specify a pattern string, you need to use the format codes listed in the following table:
character |
Description |
Example |
G |
Age Identifier |
AD |
Y |
4-digit year |
2001 |
M |
Month |
July or 07 |
D |
Day |
10 |
H |
12-hour system, a.m./p.m. (1~12) |
12 |
H |
24-hour system |
22 |
M |
Minutes |
30 |
S |
Seconds |
55 |
S |
Milliseconds |
234 |
E |
Week |
Tuesday |
D |
One day of the year |
360 |
F |
One day of the week in one months |
2 (Second Wed. In July) |
W |
A week of the year |
40 |
W |
A week in the one months |
1 |
A |
a.m./p.m. Marking |
Pm |
K |
An hour of the day (1~24) |
24 |
K |
An hour of the day, a.m./p.m. (0~11) |
10 |
Z |
Time |
Eastern Standard Time |
‘ |
Text delimited |
Delimiter |
" |
Single quotation marks |
` |
For more information about the date class, consult the Java API documentation.
2.
0, HTTP://WWW.RUNOOB.COM/JSP/JSP-HANDLING-DATE.HTML1,
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jsp-runoob:jsp Date Processing