Apache Velocity：是否存在从命令行验证模板正确性的标准方法？

Question

我们的网站使用Apache
Velocity
模板语言。我们的内容管理系统已经检查了所有生成的XML文档的格式是否正确。我们被要求在将文件推送到实际站点之前检查文档以捕获Velocity语法错误。

是否有从命令行验证Velocity模板正确性的标准方法？

我准备读入模板路径，初始化Velocity
Engine，解析模板，并捕获所有错误，如本页上所示，但是如果有现成的工具可以获取文件和配置，并吐出任何错误，那么我宁愿使用它。

更新资料

我最终要做的是：

package velocitysample;

import java.io.IOException;
import java.io.StringWriter;
import org.apache.log4j.Logger;
import org.apache.log4j.BasicConfigurator;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.Template;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.MethodInvocationException;

public class Main
{
   /** Define a static logger variable so that it references the Logger
    *  instance named "MyApp".
    */
    private static Logger logger = Logger.getLogger(Main.class);


    /**
     * @param args the command line arguments
     */
    public static void main(String[] args)
    {

        /* Set up a simple log4j configuration that logs on the console. */
        BasicConfigurator.configure();


        /* Check to see that a template path was passed on the command line. */
        if (args.length != 1)
        {
            logger.fatal("You must pass the path to a template as a " +
                    "command line argument.");
            return;
        }

        /* Pull the template filename from the command line argument. */
        String fileName = args[0];

        try
        {
            Velocity.setProperty("resource.loader", "file");
            Velocity.setProperty("file.resource.loader.class", "org.apache.velocity.runtime.resource.loader.FileResourceLoader");
            Velocity.setProperty("file.resource.loader.path", "/templates/");
            Velocity.setProperty("file.resource.loader.cache", "false");
            Velocity.setProperty("file.resource.loader.modificationCheckInterval", "0");

            Velocity.init();
        }
        catch (Exception ex)
        {
            logger.fatal("Error initializing the Veolcity engine.", ex);
            return;
        }

        boolean error = false;

        /* Create an empty Velocity context */
        VelocityContext context = new VelocityContext();

        Template template = null;

        try
        {
           template = Velocity.getTemplate(fileName);
        }
        catch( ResourceNotFoundException rnfe )
        {
           logger.error("Couldn't find the template to parse at this path: " +
                   fileName + ".", rnfe);
           error = true;
        }
        catch( ParseErrorException peex )
        {
            logger.error("Error parsing the template located at this path: " +
                    fileName + ".", peex);
            error = true;
        }
        catch( MethodInvocationException mie )
        {
            logger.error("Something invoked in the template (" + fileName +
                    ") threw an Exception while parsing.", mie);
            error = true;
        }
        catch( Exception e )
        {
            logger.error("An unexpected exception was thrown when attempting " +
                    "to parse the template: " + fileName + ".", e);
            error = true;
        }

        if (error)
        {
            return;
        }

        StringWriter sw = new StringWriter();
        try
        {
            template.merge(context, sw);
        } 
        catch (ResourceNotFoundException rnfe)
        {
            logger.error("Couldn't find the template to merge at this path: " +
                   fileName + ".", rnfe);
            error = true;
        } 
        catch (ParseErrorException peex)
        {
            logger.error("Error parsing the template at this path during merge: " +
                    fileName + ".", peex);
            error = true;
        } 
        catch (MethodInvocationException mie)
        {
            logger.error("Something invoked in the template (" + fileName +
                    ") threw an Exception while merging.", mie);
            error = true;
        } 
        catch (IOException ioe)
        {
            logger.error("Error reading the template located at this path from " +
                    "disk: " + fileName + ".", ioe);
            error = true;
        }
        catch( Exception e )
        {
            logger.error("An unexpected exception was thrown when attempting " +
                    "to merge the template: " + fileName + ".", e);
            error = true;
        }

        if (!error)
        {
            logger.info("No syntax errors detected.");
        }
    }
}

Answer 1

Velocity附带有一个名为TemplateTool的工具，该工具可转储所有引用，并且可用于验证模板的语法。

但是，您必须正确设置上下文才能验证任何模板。因此，最好的验证方法是根据自己的上下文编写自己的工具。