Question

我有一个案例，我从jar中包含的文件加载字符串模板组。使用以下机制可以正常工作：

final String urlName = new StringBuilder()
            .append("jar:file:").append(templateJar.getAbsolutePath()).append("!")
            .append(templateFileName).toString();
final URL url;
try {
        url = new URL(urlName);
} catch (MalformedURLException ex) {
        throw new GeneratorException("bad manifest url", ex);
}
final STGroup stg = new STGroupFile(url, "US-ASCII", '<', '>');

当模板文件包含

时出现困难

...
import "../../dataTypeMaps.stg"
...

字符串模板失败，并显示以下内容：

can't load group file jar:file:/home/phreed/.m2/repository/edu/vanderbilt/isis/druid/druid-template/2.0.0/druid-template-2.0.0.jar!/template/src/main/java/sponsor/orm/ContractCreator.stg
Caused by: java.lang.IllegalArgumentException: No such group file: ../../dataTypeMaps.stg
    at org.stringtemplate.v4.STGroupFile.<init>(STGroupFile.java:69)
    at org.stringtemplate.v4.STGroup.importTemplates(STGroup.java:570)
    at org.stringtemplate.v4.compiler.GroupParser.group(GroupParser.java:199)
    at org.stringtemplate.v4.STGroup.loadGroupFile(STGroup.java:619)
    at org.stringtemplate.v4.STGroupFile.load(STGroupFile.java:139)
    at org.stringtemplate.v4.STGroupFile.load(STGroupFile.java:128)
    at org.stringtemplate.v4.STGroup.lookupTemplate(STGroup.java:237)
    at org.stringtemplate.v4.STGroup.getInstanceOf(STGroup.java:172)
    at edu.vanderbilt.isis.druid.generator.Generator.build(Generator.java:215)
    at edu.vanderbilt.isis.druid.generator.DruidMojo.execute(DruidMojo.java:193)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)

是否可以使用jar进行设置以使导入有效？当没有涉及罐子时，上述方法可以正常工作。

Answer 1

简单的答案是导入文件的路径错误

...
import "dataTypeMaps.stg"
...

导入将导致从jar的根目录开始查找文件。以上导入将相当于放置在...

的文件

final String urlName = new StringBuilder()
        .append("jar:file:").append(templateJar.getAbsolutePath()).append("!")
        .append("dataTypeMaps.stg").toString();

为什么行为与模板组文件在我不知道的本机文件系统上的情况不同。为了使其工作，我更改了类路径以包含jar文件。由于这是在Maven插件的上下文中完成的，因此插件需要动态更改类路径。这是通过以下代码完成的......

 public void setTemplateJarName(String templateJarName) throws GeneratorException {
    this.templateJarName = templateJarName;
    final Thread ct = Thread.currentThread();
    final ClassLoader pcl = ct.getContextClassLoader();
    URL[] nurl;
    try {
        nurl = new URL[]{ new URL("file://"+templateJarName) };
    } catch (MalformedURLException ex) {
        throw new GeneratorException("could not load template jar", ex);
    }
    final URLClassLoader ucl = new URLClassLoader(nurl, pcl);
    ct.setContextClassLoader(ucl);
}

Answer 2

再次检查您的模板是否确实在罐子中。
使用以下代码：

如果模板是在这样的树中分派的：

/-->resources
   +--> c/     (many .st and .stg files)
   +--> cpp/   (many .st and .stg files)
   +--> java/  (many .st and .stg files)
   +--> c.stg
   +--> cpp.stg
   +--> java.stg

java.stg的内容是：

group Java;

import "java"

doNothing() ::= <<>>

要在一次调用中加载所有文件：

URL     url   = getClass().getResource( "/resources/" + templateName );
STGroup group = new STGroupFile( url, "utf-8", '<', '>' );

在我的情况下，templateName等于c.stg，cpp.stg或java.stg。

StringTemplate：如何从jar导入？

2 个答案: