freemarker自定义标签的写法和使用

写标签类（需要继承TemplateDirectiveModel接口重写execute方法）

package freemarker;

import java.io.IOException;
import java.io.Writer;
import java.util.Map;

import freemarker.core.Environment;
import freemarker.template.TemplateDirectiveBody;
import freemarker.template.TemplateDirectiveModel;
import freemarker.template.TemplateException;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateNumberModel;

public class LabelDirective implements TemplateDirectiveModel {

    @Override
    public void execute(Environment env, Map params, TemplateModel[] loopVars,
            TemplateDirectiveBody body) throws TemplateException, IOException {
        Writer out = env.getOut();
        
        //将模版里的数字参数转化成int类型的方法，，其它类型的转换请看freemarker文档
        TemplateModel paramValue = (TemplateModel) params.get("num");
        int num = ((TemplateNumberModel) paramValue).getAsNumber().intValue();
        
        out.write("Akishimo num=" + params.get("num")+"的类型为:"+paramValue.getClass());
        if (body != null) {
            body.render(env.getOut());
        }else{
            throw new RuntimeException("标签内部至少要加一个空格");
        }
    }
}

写配置和测试的类：

 1 package freemarker;
 2 
 3 import java.io.BufferedWriter;
 4 import java.io.File;
 5 import java.io.FileOutputStream;
 6 import java.io.OutputStreamWriter;
 7 import java.io.Writer;
 8 import java.util.HashMap;
 9 import java.util.Map;
10 
11 import freemarker.template.Configuration;
12 import freemarker.template.DefaultObjectWrapper;
13 import freemarker.template.Template;
14 
15 public class Test {
16 
17     public static void main(String[] args) throws Exception {
18 
19         Configuration cfg = new Configuration();
20         //将写好的标签加入，起名叫label
21         cfg.setSharedVariable("label", new LabelDirective());
22         cfg.setDirectoryForTemplateLoading(new File("temp"));
23         cfg.setObjectWrapper(new DefaultObjectWrapper());
24 
25         Template temp = cfg.getTemplate("list.ftl");
26 
27         Map root = new HashMap();
28         root.put("user", "rzy");
29 
30         /* Writer out = new OutputStreamWriter(System.out); */
31 
32         File htmlFile = new File("E:/a.html");
33         Writer out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(htmlFile), "UTF-8"));
34 
35         temp.process(root, out);
36         out.flush();
37     }
38 }

模版list.ftl先这么写

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>

<body>
<h1>${user}自定义标签输出结果</h1><br/>
<@label num=12>
 
</@label>
</body>
</html>

运行后打开e盘里面生成的a.html结果为：

http://www.cnblogs.com/Akishimo/archive/2013/05/25/3099022.html

freemarker自定义标签的写法和使用

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