freemarker自定义标签（与java合用）
2024-09-02 04:49:09
自定义类继承FreemarkerManager类，重写protected Configuration createConfiguration(ServletContext servletContext)throws TemplateException方法定义有哪些TemplateDirectiveModel类与它的别名[自定义标签名称]，通过Spring来取：
import java.util.Map;
import javax.servlet.ServletContext;
import org.apache.struts2.views.freemarker.FreemarkerManager;
import org.springframework.context.ApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import freemarker.template.Configuration;
import freemarker.template.TemplateDirectiveModel;
import freemarker.template.TemplateException;
/**
* 从spring取得所有的TemplateDirectiveModel类的对象，全部取出来，交给struts管理
* @author Administrator
*
*/
public class DirectiveFreemarkerManager extends FreemarkerManager{
@Override
protected Configuration createConfiguration(ServletContext servletContext)
throws TemplateException {
//调用你父类操作
Configuration configuration=super.createConfiguration(servletContext);
//设定在页面使用的标签的类型 (([]、<>),[]这种标记解析要快些) [] SQUARE_BRACKET_TAG_SYNTAX , <>ANGLE_BRACKET_TAG_SYNTAX
configuration.setTagSyntax(Configuration.AUTO_DETECT_TAG_SYNTAX);
//取得spring所管理所有的对象 ClassPathXmlApplication, WebAplicationContext
ApplicationContext appContext=WebApplicationContextUtils.getRequiredWebApplicationContext(servletContext);
// 获取实现TemplateDirectiveModel的bean
Map<String, TemplateDirectiveModel> beans= appContext.getBeansOfType(TemplateDirectiveModel.class);
//再把这些类，全部交给struts的freemarker来管理
//Component("upper") public class UpperDirective implements TemplateDirectiveModel
for(String key : beans.keySet()){
Object obj=beans.get(key); //TemplateDirectiveModel
if(obj!=null && obj instanceof TemplateDirectiveModel){
configuration.setSharedVariable(key, obj);
}
}
return configuration;
}
}
在struts.xml中添加：
<!-- 让struts来管理freemarker自定义标签类 struts.freemarker.manager.classname=org.apache.struts2.views.freemarker.FreemarkerManager -->
<constant name="struts.freemarker.manager.classname" value="com.xxxx.struts.DirectiveFreemarkerManager"></constant>
编写TemplateDirectiveModel，并交给Spring管理：
import java.io.IOException;
import java.io.Writer;
import java.util.Map;
import org.springframework.stereotype.Component;
import freemarker.core.Environment;
import freemarker.template.TemplateDirectiveBody;
import freemarker.template.TemplateDirectiveModel;
import freemarker.template.TemplateException;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException; /**
- 自定义指定，作用，把嵌套的内容中的小写全部转换为大写字母
- @author Administrator
/
@Component("upper")
public class UpperDirective implements TemplateDirectiveModel {
//evn 环境输出
//params 参数
//loopVars 循环
//body 内容
@Override
public void execute(Environment env, Map params,
TemplateModel[] loopVars, TemplateDirectiveBody body)
throws TemplateException, IOException {
//如果有参数 应该不支持参数
if(!params.isEmpty()){
throw new TemplateModelException(
"这个指令不允许使用参数.");
}
if(loopVars.length!=0){
throw new TemplateModelException(
"这个指令不允许使用循环参数.");
}
// 如果嵌套内容不为空的
if(body!=null){
//如果有内容，自己去重写输出流
body.render( new UpperCaseFilterWriter(env.getOut()));}</span><span style="color: #0000ff">else</span><span style="color: #000000">{</br>
</span><span style="color: #0000ff">throw</span> <span style="color: #0000ff">new</span> RuntimeException("无内容异常"<span style="color: #000000">);</br>
}</br>
}
//内部类
private static class UpperCaseFilterWriter extends Writer{
private final Writer out; //接收网页中的输出 流对象
public UpperCaseFilterWriter(Writer out){
this.out=out;
}
//cbuf 文字内容， off位移，len 文字长度
@Override
public void write(char[] cbuf, int off, int len) throws IOException {
char[] transformedChar=new char[len];
for(int i=0;i<len;i++){
transformedChar[i]=Character.toUpperCase(cbuf[i+off]);
}
out.write(transformedChar);
}
@Override
public void flush() throws IOException {
out.flush();
}
@Override
public void close() throws IOException {
out.close();
}
}
}
编写action,result—>字符串，type=”freemarker”：
<!-- 约定大于配置 /admin/Flinktype_list.action -->
<package name="freemarkerPackage" namespace="/admin" extends="commonPackage" >
<action name="*_*" class="{1}Action" method="{2}">
<result name="{2}" type="freemarker">/admin/template/{1}/{2}.ftl</result>
</action>
</package>
模板/template/upper.ftl：
<!DOCTYPE html>
<html lang="ch-ZN">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="description" content="">
<meta name="author" content="">
<title>freemarker自定义标签</title>
</head>
<body><span style="color: #0000ff"><</span><span style="color: #800000">@upper</span><span style="color: #0000ff">></span><span style="color: #000000"></br>
bar
</span><span style="color: #0000ff"><</span><span style="color: #800000">#-- </span><span style="color: #ff0000">All kind of FTL is allowed here --</span><span style="color: #0000ff">></span></br>
<span style="color: #0000ff"><</span><span style="color: #800000">#list </span><span style="color: #ff0000">["red", "green", "blue"] as color</span><span style="color: #0000ff">></span><span style="color: #000000"></br>
${color}</br>
</span><span style="color: #0000ff"></</span><span style="color: #800000">#list</span><span style="color: #0000ff">></span><span style="color: #000000"></br>
baaz</br>
</span><span style="color: #0000ff"></</span><span style="color: #800000">@upper</span><span style="color: #0000ff">></span></br></br></br> <span style="color: #0000ff"><</span><span style="color: #800000">hr</span><span style="color: #0000ff">/></span></br></br> <span style="color: #0000ff"><</span><span style="color: #800000">@cms_linktype </span><span style="color: #ff0000">limit</span><span style="color: #0000ff">="0,10"</span> <span style="color: #0000ff">></span><span style="color: #000000"></br>
请选择分类: </span><span style="color: #0000ff"><</span><span style="color: #800000">select</span><span style="color: #0000ff">></span></br>
<span style="color: #0000ff"><</span><span style="color: #800000">#list </span><span style="color: #ff0000">arrTypes as x</span><span style="color: #0000ff">></span></br>
<span style="color: #0000ff"><</span><span style="color: #800000">option </span><span style="color: #ff0000">value</span><span style="color: #0000ff">="${x.id}"</span><span style="color: #0000ff">></span>${x.typeName}<span style="color: #0000ff"></</span><span style="color: #800000">option</span><span style="color: #0000ff">></span></br>
<span style="color: #0000ff"></</span><span style="color: #800000">#list</span><span style="color: #0000ff">></span> </br>
<span style="color: #0000ff"></</span><span style="color: #800000">select</span><span style="color: #0000ff">></span></br>
<span style="color: #0000ff"></</span><span style="color: #800000">@cms_linktype</span><span style="color: #0000ff">></span></br>
</body>
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