/*
* Copyright 2010 Alibaba Group Holding Limited.
* All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package com.alibaba.antx.config.generator;
import java.io.Reader;
import java.io.Writer;
import java.net.URL;
import java.util.Formatter;
import java.util.Set;
import java.util.TreeSet;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.context.Context;
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.runtime.log.LogChute;
import org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.alibaba.antx.config.ConfigConstant;
import com.alibaba.antx.config.ConfigException;
/**
* Velocity���档
*
* @author Michael Zhou
*/
public class VelocityTemplateEngine {
private static Logger log = LoggerFactory.getLogger(VelocityTemplateEngine.class);
private static VelocityTemplateEngine instance;
private VelocityEngine engine = new VelocityEngine();
public static VelocityTemplateEngine getInstance() {
if (instance == null) {
instance = new VelocityTemplateEngine();
}
return instance;
}
/**
* ��ʼ��velocity.
*/
public VelocityTemplateEngine() {
// parser������.
engine.setProperty(RuntimeConstants.PARSER_POOL_SIZE, new Integer(ConfigConstant.VELOCITY_NUMBER_OF_PARSERS));
// ����logϵͳ.
engine.setProperty(RuntimeConstants.RUNTIME_LOG_LOGSYSTEM, new LogSystem());
// ����ݹ�
engine.setProperty("velocimacro.context.localscope", "true");
// ����resource loaderϵͳ.
engine.setProperty(RuntimeConstants.RESOURCE_LOADER, "classpath");
engine.setProperty("classpath.resource.loader.class", ClasspathResourceLoader.class.getName());
// ����velocimacro.
engine.setProperty(RuntimeConstants.VM_LIBRARY, ConfigConstant.VELOCITY_MACRO_FILE);
// ִ�г�ʼ��.
try {
engine.init();
} catch (Exception e) {
throw new ConfigException(e);
}
}
/**
* ��Ⱦģ��.
*
* @param context ��������Ϣ
* @param reader ģ��Դ
* @param writer �����
* @param url
* @return ����Ⱦ����ַ�����
* @throws Exception ��Ⱦ����
*/
public boolean render(Context context, Reader reader, Writer writer, String templateName, String configName,
URL baseURL) throws Exception {
Set<String> unknwonRefs = new TreeSet<String>();
context.put(ConfigConstant.UNKNWON_REFS_KEY, unknwonRefs);
try {
engine.evaluate(context, writer, templateName, reader);
} finally {
context.remove(ConfigConstant.UNKNWON_REFS_KEY);
}
if (!unknwonRefs.isEmpty()) {
StringBuilder buf = new StringBuilder();
Formatter fmt = new Formatter(buf);
fmt.format("Undefined placeholders found in template:%n");
fmt.format("- Template: %s%n", templateName);
fmt.format("- Descriptor: %s%n", configName);
fmt.format("- Base URL: %s%n", baseURL.toExternalForm());
fmt.format("---------------------------------------------------------------%n");
for (String ref : unknwonRefs) {
fmt.format("-> %s%n", ref);
}
fmt.format("---------------------------------------------------------------%n");
log.error(fmt.toString());
return false;
}
return true;
}
/**
* Velocity Logger
*/
private class LogSystem implements LogChute {
public void init(RuntimeServices runtimeServices) {
}
public boolean isLevelEnabled(int level) {
switch (level) {
case ERROR_ID:
return log.isErrorEnabled();
case WARN_ID:
return log.isWarnEnabled();
case INFO_ID:
return log.isInfoEnabled();
case DEBUG_ID:
return log.isDebugEnabled();
case TRACE_ID:
return log.isTraceEnabled();
default:
return false;
}
}
public void log(int level, String message) {
log(level, message, null);
}
public void log(int level, String message, Throwable t) {
message = processMessage(message);
switch (level) {
case ERROR_ID:
log.error(message);
break;
case WARN_ID:
log.warn(message);
break;
case INFO_ID:
log.info(message);
break;
case DEBUG_ID:
log.debug(message);
break;
case TRACE_ID:
log.trace(message);
break;
default:
}
}
/**
* ��ȥmessage�е�exceptionǰ��ʹ֮�����ۡ�
*/
private String processMessage(String message) {
if (message != null) {
message = message.replaceFirst("^[\\w\\.\\$]+Exception: ", "");
}
return message;
}
}
}