freemarker&velocity的使用
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?下面是我写的关于模板引擎的列子，希望对大家有所帮助
首先看下目录结构：
?所需要的jar包：
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第一步：编写接口TemplateEngine.java
package templatetest.templateInterface;import java.util.Map;public interface TemplateEngine {void run(Map context) throws Exception;}?第二步：编写工具类Constants.java
package templatetest.util;public class Constants {public static final String ENGINE_TYPE_VELOCITY = "volecity";public static final String ENGINE_TYPE_FREEMARKER = "freemarker";}?第三步：编写抽象类AbstractTemplateEngine.java
package templatetest.templateImpl;import java.io.File;import java.io.IOException;import java.io.OutputStreamWriter;import java.io.StringWriter;import java.io.Writer;import java.util.Map;import java.util.Properties;import org.apache.velocity.VelocityContext;import org.apache.velocity.app.Velocity;import templatetest.templateInterface.TemplateEngine;import templatetest.util.Constants;import freemarker.template.Configuration;import freemarker.template.DefaultObjectWrapper;import freemarker.template.Template;public abstract class AbstractTemplateEngine implements TemplateEngine{public abstract String getTemplatePath();public abstract String getTemplate();public abstract String getEngineType();public void run(Map context) throws Exception {if(Constants.ENGINE_TYPE_FREEMARKER.equals(getEngineType())){executeFreemarker(context);}else{executeVelocity(context);}}private void executeFreemarker(Map context) throws Exception {Configuration cfg = new Configuration();cfg.setDirectoryForTemplateLoading(new File(getTemplatePath()));cfg.setObjectWrapper(new DefaultObjectWrapper());cfg.setCacheStorage(new freemarker.cache.MruCacheStorage(20, 250));Template template = cfg.getTemplate(getTemplate());Writer write = new OutputStreamWriter(System.out);template.process(context, write);write.flush();}private void executeVelocity(Map context) throws Exception {Properties p = new Properties();p.setProperty(Velocity.FILE_RESOURCE_LOADER_PATH, getTemplatePath());Velocity.init(p);VelocityContext velocityContext = new VelocityContext(context);org.apache.velocity.Template template = null;template = Velocity.getTemplate(getTemplate());StringWriter sw = new StringWriter();template.merge(velocityContext, sw);System.out.println(sw.toString());}}?
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第四步：分别编写FreemarkerTemplateEngine.java和VelocityTemplateEngine.java
package templatetest.templateImpl;import java.util.Map;import templatetest.util.Constants;public class FreemarkerTemplateEngine extends AbstractTemplateEngine {public static String DEFAULT_TEMPLATE = "FreemarkerExample1.ftl";@Overridepublic String getEngineType() {return Constants.ENGINE_TYPE_FREEMARKER;}@Overridepublic String getTemplate() {return DEFAULT_TEMPLATE;}@Overridepublic String getTemplatePath() {return null;}public void run(Map context) throws Exception{super.run(context);}}?
package templatetest.templateImpl;import java.util.Map;import templatetest.util.Constants;public class VelocityTemplateEngine extends AbstractTemplateEngine {public static String DEFAULT_TEMPLATE ="VelocityExample1.vm";@Overridepublic String getEngineType() {return Constants.ENGINE_TYPE_VELOCITY;}@Overridepublic String getTemplate() {return DEFAULT_TEMPLATE;}@Overridepublic String getTemplatePath() {return null;}public void run(Map context) throws Exception{super.run(context);}}?
第五步：编写工厂类TemplateFactory.java
package templatetest.factory;import java.util.HashMap;import java.util.Map;import javax.jms.ObjectMessage;import templatetest.templateImpl.FreemarkerTemplateEngine;import templatetest.templateImpl.VelocityTemplateEngine;public class TemplateFactory {private static TemplateFactory instance;private static Map objectMap;static{instance = new TemplateFactory();}public TemplateFactory(){super();this.objectMap = new HashMap();synchronized(this){objectMap.put("freemarker", new FreemarkerTemplateEngine(){public String getTemplatePath(){return "D:/tomcat6/webapps/jc6/templatetest/";}});objectMap.put("velocity", new VelocityTemplateEngine(){public String getTemplatePath(){return "D:/tomcat6/webapps/jc6/templatetest/";}});}}public static TemplateFactory getInstance(){return instance;}public static Object getBean(String key){return objectMap.get(key);}}?
?第六步：编写模板
freemarker template test:string test: ${user}---${map.url}----${map.name}Long test:${age}condition test:<#if user == 'longzhun'>list test:<#list numberList as aa>${aa}</#list></#if>date test:${date?string("yyyy-MM-dd")}date test:${date?string("MMM/dd/yyyy")}date test:${date?string("")}2011-5-232011-5-23?
velocity template test:string test: ${user}---${map.url}----${map.name}Long test:${age}condition test:#if($user == "longzhun")list test:#foreach($aa in $numberList) $aa#end#enddate test:${date}?第七步：准备数据，测试
package templatetest.test;import java.util.ArrayList;import java.util.Date;import java.util.HashMap;import java.util.List;import java.util.Map;import templatetest.factory.TemplateFactory;import templatetest.templateInterface.TemplateEngine;public class TemplateTest {public static void main(String[] args) throws Exception {//准备数据Map map = new HashMap();map.put("url", "yesc.com.cn");map.put("name", "管理员");List list = new ArrayList();list.add("1");list.add("2");Map context = new HashMap();context.put("user", "longzhun");context.put("age", new Long(25000));context.put("date", new Date());context.put("numberList", list);context.put("map", map);TemplateEngine freemarkerEngine = (TemplateEngine) TemplateFactory.getInstance().getBean("freemarker");freemarkerEngine.run(context);TemplateEngine volecityEngine = (TemplateEngine) TemplateFactory.getInstance().getBean("velocity");volecityEngine.run(context);}}?
?最后奉上文档：
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