谷歌应用程序引擎的速度框架 [英] velocity framework on google app engine

问题描述

我试图在谷歌应用引擎上使用速度框架。我用一种主要方法编写了一个小程序，并尝试在本地运行它。我得到以下异常：

 
线程main中的异常org.apache.velocity.exception.VelocityException：未能初始化一个实例具有当前运行时配置的org.apache.velocity.runtime.log.ServletLogChute。 
 at org.apache.velocity.runtime.log.LogManager.createLogChute（LogManager.java:206）
 at org.apache.velocity.runtime.log.LogManager.updateLog（LogManager.java:255） 
 at org.apache.velocity.runtime.RuntimeInstance.initializeLog（RuntimeInstance.java:795）
 at org.apache.velocity.runtime.RuntimeInstance.init（RuntimeInstance.java:250）
 （Main.java:10）
引起：java.lang.UnsupportedOperationException：无法检索ServletContext来自应用程序属性
位于org.apache.velocity.runtime.log.ServletLogChute.init（ServletLogChute.java:73）
位于org.apache.velocity.runtime.log.LogManager.createLogChute（LogManager。 java：157）
 ... 5 more 
 

这是我的程序：

  import java.io.StringWriter; 
 import org.apache.velocity.app.VelocityEngine; 
 import org.apache.velocity.Template; 
 import org.apache.velocity.VelocityContext; 
 
 public class Main {
 public static void main（String [] args）throws Exception {
 / * first，获取并初始化引擎* / 
 VelocityEngine ve = new VelocityEngine（）; 
 ve.init（）; 
 / *接下来，获取模板* / 
模板t = ve.getTemplate（helloworld.vm）; 
 / *创建一个上下文并添加数据* / 
 VelocityContext context = new VelocityContext（）; 
 context.put（name，World）; 
 / *现在将模板渲染成StringWriter * / 
 StringWriter writer = new StringWriter（）; 
 t.merge（context，writer）; 
 / *显示世界* / 
 System.out.println（writer.toString（））; 
 
 
 $ / code $ / pre 
 $ b $ p 
同一个程序在正常的eclipse项目上运行得很好。什么可能是问题？
解决方案 
似乎只是 ServletLogChute 类需要 ServletContext ，Velocity本身可以完全独立于Servlet环境。
 
 
 
 t有一个servelt日志，在调用 ve.init（）之前尝试添加以下内容：
  ve.setProperty（runtime.log.logsystem.class，org.apache.velocity.runtime.log.NullLogChute）; 
  
 ...或 
 / releases-velocity-1.6.2 / developer-guide.html＃Configuring_Loggingrel =noreferrer
i am trying to use velocity framework on google app engine. i wrote a small program with a main method and tried running it locally. i get the following exception :
Exception in thread "main" org.apache.velocity.exception.VelocityException: Failed to initialize an instance of org.apache.velocity.runtime.log.ServletLogChute with the current runtime configuration.
  at org.apache.velocity.runtime.log.LogManager.createLogChute(LogManager.java:206)
  at org.apache.velocity.runtime.log.LogManager.updateLog(LogManager.java:255)
  at org.apache.velocity.runtime.RuntimeInstance.initializeLog(RuntimeInstance.java:795)
  at org.apache.velocity.runtime.RuntimeInstance.init(RuntimeInstance.java:250)
  at org.apache.velocity.app.VelocityEngine.init(VelocityEngine.java:107)
  at Main.main(Main.java:10)
Caused by: java.lang.UnsupportedOperationException: Could not retrieve ServletContext from application attributes
  at org.apache.velocity.runtime.log.ServletLogChute.init(ServletLogChute.java:73)
  at org.apache.velocity.runtime.log.LogManager.createLogChute(LogManager.java:157)
  ... 5 more
Here is my program:
import java.io.StringWriter;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;

public class Main {
 public static void main(String[] args) throws Exception{
        /*  first, get and initialize an engine  */
        VelocityEngine ve = new VelocityEngine();
        ve.init();
        /*  next, get the Template  */
        Template t = ve.getTemplate( "helloworld.vm" );
        /*  create a context and add data */
        VelocityContext context = new VelocityContext();
        context.put("name", "World");
        /* now render the template into a StringWriter */
        StringWriter writer = new StringWriter();
        t.merge( context, writer );
        /* show the World */
        System.out.println( writer.toString() );    
 }
}
the same program runs perfectly fine on a normal eclipse project. what could be the problem?
解决方案
Seems to only be the ServletLogChute class that requires the ServletContext, Velocity itself can work entirely standalone from a Servlet environment.


Since you obviously don't have a servelt log, try adding the following before you call ve.init():
ve.setProperty("runtime.log.logsystem.class", "org.apache.velocity.runtime.log.NullLogChute");
...or check here if you have specific logging requirements.

                        
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