I have a java enum that is used in my web application. I also have a lot of javascript code that refers to the values of the enum. It would be ideal If I could generate a javascript file from the enum as part of the maven build process. Does anyone know of a project that solves this problem or of an elegant way to tackle it?
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2 Answers
It turns out that there is a great way to do it using a groovy maven plugin as a "prepare-package" phase. This is the code : In your pom.xml add this entry :
<plugin>
<groupId>org.codehaus.groovy.maven</groupId>
<artifactId>gmaven-plugin</artifactId>
<executions>
<execution>
<id>script-prepare-package1</id>
<phase>prepare-package</phase>
<goals>
<goal>execute</goal>
</goals>
<configuration>
<source>${basedir}/src/main/groovy/GenerateJavaScriptEnum.groovy</source>
</configuration>
</execution>
</executions>
</plugin>
This is how the groovy script, GenerateJavaScriptEnum.groovy, looks like :
def fields = []
com.foo.bar.YourEnum.values().each() { f->
fields << "${f.name()} : \"${f.getId()}\""
}
if (fields) {
log.info("Generating Javascript for com.foo.bar.YourEnum")
[
new File("${project.build.directory}/${project.build.finalName}/js"),
new File("${project.basedir}/src/main/webapp/js")
].each() { baseOutputDir->
if (!baseOutputDir.exists()) {
baseOutputDir.mkdirs()
log.info("Created output dir ${baseOutputDir}")
}
def outfile = new File(baseOutputDir, "YourEnum.js")
log.info("Generating ${outfile}")
def writer = outfile.newWriter("UTF-8")
writer << "// FILE IS GENERATED FROM com.foo.bar.YourEnum.java.\n"
writer << "// DO NOT EDIT IT. CHANGES WILL BE OVERWRITTEN BY THE BUILD.\n"
writer << "YourEnum = {\n"
writer << fields.join(",\n")
writer << "\n}"
writer.close()
}
}
Comments
I had the same problem and ended up creating a custom tag that would allow me to iterate over the enum in my jsp,
public static Enum<?>[] getValues(String klass) {
try {
Method m = Class.forName(klass).getMethod("values", (Class<?>[]) null);
Object obj = m.invoke(null, (Object[]) null);
return (Enum<?>[]) obj;
} catch (Exception ex) {
return null;
}
}
Then in my jsp I just do,
var MyEnum = [
<c:forEach var="type" items="${foocustomtags:enumiter('com.foo.MyEnum')}">
'${type.value}': '${type.text}',
</c:forEach>
];
1 Comment
Assaf Karmon
This is pretty useful so upvoted it, but I would still love to have some code generation so that I would be able to remove all the magic strings from the javascript code. Thanks!