Trail: Deployment
Lesson: Deployment In-Depth
Section: Deployment Toolkit

部署 Applet

You can deploy applets by using the runApplet function of the Deployment Toolkit script. The runApplet function ensures that the required minimum version of the Java Runtime Environment (JRE) software exists on the client and then runs the applet. The runApplet function generates an HTML <applet> tag with the information provided.

注意:Depending on the type of browser, you might be unable to view the HTML generated by the Deployment Toolkit script when you try to view the source for the web page. To view the generated HTML, try saving the HTML page after it has been loaded, or use a tool such as Firebug (a Mozilla Firefox add-on).

You can deploy applets by specifying the deployment options as attributes and parameters of the <applet> tag. You can also specify deployment options in a Java Network Launch Protocol (JNLP) file to take advantage of advanced features. See the Java Network Launch Protocol topic for more information about this protocol.

注意:

If the client does not have the required minimum version of the JRE software, the Deployment Toolkit script redirects the browser to http://www.java.com to allow users to download the latest JRE software. On some platforms, users might be redirected before they can view the web page containing the applet.

The parameters to the runApplet function vary depending on whether you are using JNLP. Applets deployed by using JNLP can run only if the next generation Java Plug-in software exists on the client machine (the next generation Java Plug-in software was introduced in the Java Platform, Standard Edition 6 update 10 release).

The next section shows how to use the runApplet function in the HTML page that will display the applet. The following usage scenarios are described:

Specifying deployment options as attribute and parameter name-value pairs
Using the jnlp_href parameter to specify deployment options in a JNLP file
Specifying attribute and parameter name-value pairs as well as a JNLP file(enables applet to run on the old and next generation Java Plug-in software)

Function signature:runApplet: function(attributes, parameters, minimumVersion)

Parameters:

attributes – The names and values of the attributes of the generated <applet> tag
parameters – The names and values of the <param> tags in the generated <applet> tag
minimumVersion – The minimum version of the JRE software that is required to run this applet

Usage:

Specifying deployment options as attribute and parameter name-value pairs
The attributes and parameters passed as name-value pairs are written out as attributes and nested <param> tags in the generated <applet> tag. Applets deployed in this manner can be run by the old Java Plug-in software.
```
// launch the Java 2D applet on JRE version 1.6.0
// or higher with one parameter (fontSize)
<script src=
    "https://www.java.com/js/deployJava.js"></script>
<script>
    var attributes = {code:'java2d.Java2DemoApplet.class',
        archive:'Java2Demo.jar', width:710, height:540};
    var parameters = { fontSize:16, permissions:'sandbox' };
    var version = '1.6';
    deployJava.runApplet(attributes, parameters, version);
</script>
```
Open DeployUsingNameValuePairs.html in a browser to view the the Java2D applet.

注意:如果你没有看到 applet 正在运行，则需要至少安装 Java SE Development Kit (JDK) 7 版本。
Using the jnlp_href parameter to specify deployment options in a JNLP file
The attributes and parameters (jnlp_href in this case) passed as name-value pairs are written out as attributes and nested <param> tags in the generated <applet> tag. Applets deployed in this manner can be run by the next generation Java Plug-in software only. It is better to specify the applet's width and height as attributes as follows:
```
<script src="https://www.java.com/js/deployJava.js"></script>
<script> 
    var attributes = { code:'java2d.Java2DemoApplet', width:710, height:540 }; 
    var parameters = { jnlp_href: 'java2d.jnlp' }; 
    deployJava.runApplet(attributes, parameters, '1.6'); 
</script>
```
Open DeployUsingJNLP.html in a browser to view the the Java2D applet.

注意: If you don't see the applet running, you need to install at least the Java SE Development Kit (JDK) 6 update 10 release.
Specifying attribute and parameter name-value pairs as well as a JNLP file
Applets deployed by using JNLP will run only if end users have the next generation Java Plug-in software running on their browsers. If you would like your applet to run on the old Java Plug-in software also, specify deployment options using attribute and parameter name-value pairs as well as a JNLP file.
```
    
<script src="https://www.java.com/js/deployJava.js"></script>
<script>  
    var attributes = {code:'java2d.Java2DemoApplet.class', 
            archive:'Java2Demo.jar', width:710, height:540}; 
    var parameters = { fontSize:16, jnlp_href:'java2d.jnlp' }; 
    var version = '1.6' ; 
    deployJava.runApplet(attributes, parameters, version);      
</script>
```

The following guidelines are helpful if some deployment options have different values in the attribute name-value pairs and in the JNLP file:

Specify width and height as attribute name-value pairs (not in the JNLP file).
Specify parameters such as image and boxbgcolor as parameter name-value pairs (not in the JNLP file). These parameters are needed early on in the applet startup process.
In the JNLP file, leave the codebase attribute empty or specify an absolute URL. When the codebase attribute is left empty, it defaults to the directory containing the JNLP file.
If the applet is launched using a JNLP file, the values for the code, codebase, and archive attributes are taken from the JNLP file. If these attributes are also specified separately as attribute name-value pairs, the attribute name-value pairs are ignored.

Open DeployUsingNameValuePairsAndJNLP.html in a browser to view the the Java2D applet.

注意:如果你没有看到 applet 正在运行，则需要至少安装 Java SE Development Kit (JDK) 7 版本。

Download source codefor the Run Applet example to experiment further.