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scenario

When the JDK is installed on the server, the time zone rules that support the JDK version are provided by default. But time zone rules may change, so how do you keep them up to date?

This section describes the TZUpdater tool

The TZUpdater tool provided allows you to update your installed Java Development Kit (JDK) and Java runtime environment (JRE) software with updated time zone data to accommodate daylight saving Time (DST) changes in different countries. Oracle relies on time zone data exposed through IANA’s Time Zone database.

If you are unable to use the latest JDK or JRE update of Oracle, or if the time zone data on the latest version is not the latest available, the TZUpdater tool provides a way to update the time zone data while leaving other system configurations and dependencies unchanged.

TZUpdater tool usage

TZUpdater JDK/JRE software instance used to execute the tool. The JDK/JRE software is modified with each execution. To manage tools to multiple instances of JDK/JRE software.

Before you can run the TZUpdater tool on your installed JDK/JRE software, you must stop any running services for the JDK/JRE software on your operating system.

Run the TZUpdater tool with the following command:

java -jar tzupdater.jar options
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To successfully update the time zone data, you should ensure that you have sufficient permissions to modify the JDK_HOME /jre/lib or JRE_HOME /lib directories.

If no options are specified, a usage message is displayed. To update the time zone data, use the -l or -f option.

Manual upgrade

Note:

1. Before running TZUpdater on the installed JDK/JRE software, you must stop any running services of the JDK/JRE software on the operating system.

2. To successfully update the time zone data, you should ensure that you have sufficient permissions to make the changesJDK_HOME /jre/liborJRE_HOME /libDirectory. (In Linux, you must have write permission for the JRE directory. Windows: Run CMD as administrator)

3, If the system has multiple JDK/JRE, you need to use this tool in each JDK/JRE (each JDK/JRE must be operated once).

4, After the update is successful, restart the application service on the JDK/JRE instance (if it has not been updated, try restarting the server)

Operation steps:

1. Download the tzupdater.jar package provided by Oracle. Download address

www.oracle.com/java/techno…

Put tzupdater.jar in the Java directory bin, for example

"C: \ Program Files \ JAVA \ JAVA - 1.8.0 comes with - its - 1.8.0.201 \ bin \ tzupdater jar";Copy the code

2. Check the version of the database in the current time zone. For example, in Windows, run CMD as the administrator to switch to the directory corresponding to tzupdater.jar.

java -jar tzupdater.jar -V
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3, online update, take Windows as an example, run CMD as administrator, switch to the corresponding directory of tzupdater.jar :(choose either the third or the fourth update method)

java -jar tzupdater.jar -l https://www.iana.org/time-zones/repository/tzdata-latest.tar.gz
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As shown in the figure, tzData2021A has been successfully updated.

The updated file is placed in jre/lib/tzdb.dat, as shown, which has a backup history of the version.

4, offline update: to download the latest time zone data, download address:

Data.iana.org/time-zones/…

In Windows, run CMD as an administrator. Switch to the directory corresponding to tzupdater.jar:

java -jar tzupdater.jar -l file:///[path]/tzdata.tar.gz 
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Note:

For Windows, you are advised to save it in the root directory of drive C, and the path directory should not contain Chinese characters.

Run CMD as administrator (write permission required);

As shown in the command above, the/after file is three

5. Run the command in Step 2 to check whether the database version in the current time zone is updated successfully.

Automatic service upgrade

Steps:

1. Set the scheduled task (operating system configuration only) and execute the command script of tzupdater to update the time zone;

2. Create a new time zone service to provide the time zone and DAYLIGHT saving time (DST) rule reading service externally.

3. In the time zone service, write a synchronization button to execute the command script of tzupdater updating the time zone;

4. In the timeZone service, the timeZone data is periodically written to the customized timeZone table. Maintains timeZone data by adding, modifying, and deleting timeZone data.

Advantages of this idea:

1. Other services do not need to stop the service to update the time. The latest time zone data can be obtained by directly invoking the time zone service data.

2, the benefits of automation, avoid manual maintenance of the time zone tedious, manual intervention may cause problems risk;

Time zone services and other business services are split to facilitate future expansion.

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Reference:

TZUpdater: www.oracle.com/java/techno…

IANA Time zone data version: data.iana.org/time-zones/…

JRE time zone data in software version: www.oracle.com/java/techno…