Java Control Panel In Windows 11
Roseanne Devon
This topic describes the Java Control Panel, which is used to control how Java and JavaFX applications that are embedded in a browser or are launched from a browser run on your computer. The settings in the Java Control Panel are not used by standalone and self-contained applications.
View and delete temporary files used by the Java Plug-in, which runs Java applications that are embedded in a browser, and by Java Web Start, which enables you to run Java applications over the network.
The General tab contains the following sections: About, Network Settings, and Temporary Internet Files. This tab also indicates if Java is enabled in the browser, which is controlled in the Security tab.
Select this option to specify the URL for the JavaScript file (.js or .pac extension) that contains the FindProxyForURL function. FindProxyForURL has the logic to determine the proxy server to use for a connection request.
Click View to show the Java Cache Viewer dialog. This dialog enables you to list applications, resources, and deleted applications stored in the Java cache. In addition, you can perform the following actions:
The Update tab is available on Microsoft Windows and OS X for both the 32-bit and 64-bit versions of the JRE, and only for users with Administrative privileges. On Microsoft Windows, if the JRE is installed and this panel is not available, launch the Java Control Panel directly from the command line (\bin\javacpl.exe). Figure 20-2 shows the Update tab.
The Update tab is used with the Java Update Scheduler (jusched.exe) to provide the latest Java updates to the end user. This tab enables you to automatically or manually update all JREs (including 32-bit and 64-bit versions) installed on your system.
Select Check for Updates Automatically to have your JRE updated automatically on a schedule that you set. From the Notify Me drop-down list, choose to be notified either before the update is downloaded, or after the updated is downloaded but before the update is installed.
Click Advanced to set up the schedule for updates. To set how often the system checks for updates, choose Daily, Weekly, or Monthly. The default is monthly. For daily updates, you can select the time of the day for the update. For weekly updates, you can select the day of the week and the time of the day. For monthly updates, you can select the day of the week and the time of the day. Monthly updates check weekly and notify you within 30 days that an update is available, however, if an update is considered critical you are notified within a week of its release.
On Microsoft Windows platforms, the Java Update Scheduler, jusched.exe, is used to launch automatic updates when the option to update automatically is selected in the Update tab. jusched.exe runs as a background process that launches the Update Manager at predefined intervals set by the user using the Advanced button of the Update tab. The Update Manager coordinates the update process.
jusched.exe is launched when the user reboots the computer after installing the JDK or JRE. It is normally transparent to the user, but can be viewed in the Processes tab of the Windows Task Manager. If you do not want the scheduler to run, use the End Process button of the Processes tab to kill the process.
Click View to show the Java Runtime Environment Settings dialog, which provides information on the JREs that are installed on your system, and enables you to choose the JREs that you want to use to run applications that are embedded in a web page or launched from a browser.
The Java Runtime Environment Settings dialog has two tabs, User and System. Both tabs show a table that contains information on the JREs that are installed on your system. The User tab shows all of the registered JREs and JREs that the user has added. The System tab shows the JRE that was used to start the Java Control Panel.
Enabled: Flag that indicates which of the JRE versions are considered when running an application using Java Plug-in or Java Web Start. Settings in the Java Control Panel do not apply to standalone or self-contained applications. If the check box for a JRE is not selected, then Java Plug-in and Java Web Start will not use the JRE to launch Java applications. However, the current JRE might be used even if it is not marked as enabled.
Microsoft Windows shows all of the JREs that are installed on a computer. The Java Control Panel finds the JREs by looking in the registry. On Solaris, Linux, and OS X, the JRE that Java Web Start or Java Plug-in is using to deploy applications is the JRE that is considered registered. Therefore, use the Find, Add, and Remove buttons to change which JREs are listed in the table. On OS X, only the currently installed JRE is displayed, JDKs are not included.
You can override the Java Plug-in default startup parameters by specifying custom options in the Runtime Parameters column for a JRE. With the exception of setting classpath and cp, the syntax is the same as that used with parameters for the java command line invocation. See the java command for a full list of command line options:
Assertion is disabled in Java Plug-in code by default. The effect of assertion is determined during Java Plug-in startup. If you change the assertion settings in the Java Plug-in Control Panel, you must restart the browser for the new settings to take effect.
Similar to tracing, logging is a facility to redirect any output in the Java Console to a log file (plugin.log or javaws.log) using the Java Logging API. Use the following parameter to turn on logging:
Tracing and logging set through the Java Control Panel take effect when the Plug-in is launched. However, changes made through the Java Control Panel while a Plug-in is running have no effect until a restart.
The following networking parameters can also be used to set the connect and read timeout values for the protocol handlers used by java.net.URLConnection. The default value set by the protocol handlers is -1, which means there is no timeout set.
sun.net.client.defaultConnectTimeout specifies the timeout in milliseconds to establish the connection to the host. For example, for HTTP connections, it is the timeout when establishing the connection to the HTTP server. For FTP connections it is the timeout when establishing the connection to FTP servers.
To prevent any Java application from running in a browser or being launched from a browser, make sure that the Enable Java content in the browser option is not selected. This option is selected by default.
The security level determines the criteria used to allow or block a Java application from running within a browser or being launched from a browser. As the security level is increased, more restrictions are placed on allowing an application to run, and stronger warnings are issued to the user.
Very High - Applications that are signed with a valid certificate that is located in the Signer CA keystore, and include the Permissions attribute in the manifest for the main JAR file are allowed to run with security prompts. All other applications are blocked.
High - Applications that are signed with a valid certificate that is located in the Signer CA keystore, and include the Permissions attribute in the manifest for the main JAR file are allowed to run with security prompts. Applications are also allowed to run with security prompts when the revocation status of the certificate cannot be checked. All other applications are blocked.
The Security Level setting affects plug-in applets, Java Web Start applications, embedded JavaFX applications, and access to the native deployment toolkit plug-ins. This setting does not affect standalone or self-contained Java applications.
The exception site list contains a list of URLs that host RIAs that users want to run even if the RIAs are normally blocked by security checks. RIAs from the sites listed are allowed to run with applicable security prompts. Click Edit Site List to add, edit, and remove items.
If an active deployment rule set is installed on the system, the link View the active Deployment Rule Set is shown before the Manage Certificates button. Click the link to view the rule set. For information on the certificate used to sign the rule set, click the View Certificate Details link in the Deployment Rule Set - More Information window.
When a rule set is available, the rules determine if a RIA is run without security prompts, run with security prompts, or blocked. For more information on deployment rules, see Chapter 28, "Deployment Rule Set". For more information on security prompts, see Section 23.5, "Security Dialogs."
An option to hide a prompt in the future is included in some security prompts that are shown when an application starts. To insure the continued security of your system, it is recommended that you periodically restore the prompts that were hidden. Seeing the prompts again provides an opportunity to review the applications and ensure that you still want them to run.
To restore the prompts that were previously hidden, click Restore Security Prompts. When asked to confirm the selection, click Restore All. The next time an application is started, the security prompt for that application is shown.
User-level and system-level certificates used to sign RIAs that you run can be managed by clicking Manage Certificates. From the Certificates dialog, you can import, export, remove, and view the details for certificates. Information is provided for the following types of certificates:
You can export, import, remove, and view the details of user-level certificates using the buttons provided in the Certificates dialog. To export, remove, or view the details, first select a certificate from the list.
To specify a user-level keystore in a location other than the default location, set properties in the user-level deployment.properties file. See Chapter 21, "Deployment Configuration File and Properties" for information on configuration properties. The following table describes the property to set for each type of certificate.
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