FreeMarker几种不同方式的展现数据

FreeMarker是一个模板引擎，一个基于模板生成文本输出的通用工具。
本文主要写了3种方法通过freemarker与java对象数据结合，将数据展现于前台页面。

注：项目jar包

commons-beanutils-1.7.0.jar
commons-collections-3.1.jar
commons-fileupload-1.2.1.jar
commons-io-1.3.2.jar
commons-lang-2.5.jar
commons-logging-1.0.4.jar
ezmorph-1.0.6.jar
freemarker-2.3.13.jar
freemarker.jar
json-lib-2.4-jdk15.jar
ognl-2.6.11.jar
spring-core-2.0.8.jar
struts2-core-2.1.6.jar
xwork-2.1.2.jar

公共类：
User.java代码如下

package com.hsinghsu.test.model;

public class User
{
    private int id;

    private String name;

    private int age;

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    public int getId()
    {
        return id;
    }

    public void setId(int id)
    {
        this.id = id;
    }

    public int getAge()
    {
        return age;
    }

    public void setAge(int age)
    {
        this.age = age;
    }
    
}

UserDao.java 代码如下，用于生成模拟数据：

package com.hsinghsu.test.dao;

import java.util.ArrayList;
import java.util.List;

import com.hsinghsu.test.model.User;

public class UserDao
{
    public List getUserList()
    {
        List list = new ArrayList();
        User user = null;
        for (int i = 0; i < 10; i++)
        {
            user = new User();
            user.setId(i);
            user.setName("name" + i);
            user.setAge(i + i);
            list.add(user);
        }
        
        return list;
    }

}

1.使用struts配置文件直接将数据渲染到ftl中

UserActionFTL.java Action代码如下：

package com.hsinghsu.test.action;

import java.util.List;

import com.hsinghsu.test.dao.UserDao;
import com.hsinghsu.test.model.User;
import com.opensymphony.xwork2.ActionSupport;

/**
 * 通过struts配置文件直接渲染ftl
 * @author HsingHsu
 *
 */
public class UserActionFTL extends ActionSupport
{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    private List uList;

    public String execute()
    {
        System.out.println("===begin");

        UserDao userDao = new UserDao();

        uList = userDao.getUserList();

        return SUCCESS;
    }

    public List getuList()
    {
        return uList;
    }

    public void setuList(List uList)
    {
        this.uList = uList;
    }

}

struts.xml配置文件如下：

  

	

		
		
			/templates/userStrutsTemplate.ftl
		

	

userStrutsTemplate.ftl文件配置如下：

    <#list uList as user>   
    
   
    
   
        
id
   
        
name
  
        
age
    
    
   
        
${user.id}
   
        
${user.name}
        
${user.age}
    
	

2.通过生成html文件，返回该html的url

FTL2HtmlFlie.java 通过ftl生成html文件类代码如下：

package com.hsinghsu.test.util;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.util.Locale;
import java.util.Map;

import org.apache.struts2.ServletActionContext;

import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;

public class FTL2HtmlFlie
{
    /**
     * 
     * @param ftlPath ftl的路径
     * @param ftlName ftl的名称
     * @param htmlPath 要生成的html路径
     * @param htmlName 要生成的html名称
     * @param dataMap 需要渲染到ftl中的map数据
     * @return
     */
    public static boolean createHtmlFile(String ftlPath, String ftlName,
            String htmlPath, String htmlName, Map dataMap)
    {
        boolean result = false;

        // 创建Configuration对象
        Configuration cfg = new Configuration();
        // 设置FreeMarker的模版文件位置
        cfg.setServletContextForTemplateLoading(
                ServletActionContext.getServletContext(), ftlPath);
        cfg.setEncoding(Locale.getDefault(), "utf-8");

        // 创建Template对象
        Template template = null;
        try
        {
            template = cfg.getTemplate(ftlName);
        }
        catch (IOException e1)
        {
            e1.printStackTrace();
        }
        template.setEncoding("utf-8");

        String path = ServletActionContext.getServletContext().getRealPath("/");

        File dir = new File(path + htmlPath);
        if (!dir.exists())
        {
            dir.mkdirs();
        }

        File fileName = new java.io.File(path + htmlPath + htmlName);
        System.out.println("html file:" + fileName.getPath());

        Writer writer = null;

        try
        {
            writer = new BufferedWriter(new OutputStreamWriter(
                    new FileOutputStream(fileName), "utf-8"));
        }
        catch (UnsupportedEncodingException e)
        {
            e.printStackTrace();
        }
        catch (FileNotFoundException e)
        {
            e.printStackTrace();
        }
        try
        {
            // 生成静态页面
            template.process(dataMap, writer);
            result = true;
        }
        catch (TemplateException e)
        {
            e.printStackTrace();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        try
        {
            writer.flush();
            writer.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

        return result;
    }
}

UserActionHtmlFile.java Action代码如下：

package com.hsinghsu.test.action;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.hsinghsu.test.dao.UserDao;
import com.hsinghsu.test.model.User;
import com.hsinghsu.test.util.FTL2HtmlFlie;
import com.opensymphony.xwork2.ActionSupport;

/**
 * 生成html文件，返回html文件给前台
 * @author HsingHsu
 *
 */
public class UserActionHtmlFile extends ActionSupport
{
    /**
     * 
     */
    private static final long serialVersionUID = -16215231106028452L;

    private String returnURL;

    public String execute() throws Exception
    {
        UserDao userDao = new UserDao();
        List uList = userDao.getUserList();

        Map> dataMap = new HashMap>();
        dataMap.put("userList", uList);

        String ftlPath = "/templates/";
        String ftlName = "htmlFileTemplate.ftl";
        String htmlPath = "/html/user/";
        String htmlName = "user.html";

        boolean result = FTL2HtmlFlie.createHtmlFile(ftlPath, ftlName,
                htmlPath, htmlName, dataMap);
        this.returnURL = htmlPath + htmlName;

        if (result)
        {
            return SUCCESS;
        }
        else
        {
            return ERROR;
        }

    }

    public String getReturnURL()
    {
        return returnURL;
    }

    public void setReturnURL(String returnURL)
    {
        this.returnURL = returnURL;
    }

}

struts.xml配置文件如下：

  

	

		
		
			${returnURL}
		

	

htmlFileTemplate.ftl文件配置如下：

    <#list userList as user>   
    
   
    
   
        
id
   
        
name
  
        
age
    
    
   
        
${user.id}
   
        
${user.name}
        
${user.age}
    
	

3.通过ftl生成html字符串流，将生成的html字符串返回给前台。

FTL2String.java 通过ftl生成html字符串类代码如下：

package com.hsinghsu.test.util;

import java.io.IOException;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;

import org.apache.struts2.ServletActionContext;

import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;

/**
 * 
 * @author HsingHsu
 * 
 */
public class FTL2String
{
    
    /**
     * 
     * @param ftlPath ftl的路径
     * @param ftlName ftl的名称
     * @param jsonDataString 需要渲染的json字符串
     * @return
     * @throws IOException
     * @throws TemplateException
     */
    public static String createHtmlString(String ftlPath, String ftlName,
            String jsonDataString) throws IOException, TemplateException
    {
        String resultString;

        // 创建Configuration对象
        Configuration cfg = new Configuration();
        // 设置FreeMarker的模版文件位置
        cfg.setServletContextForTemplateLoading(
                ServletActionContext.getServletContext(), ftlPath);
        cfg.setEncoding(Locale.getDefault(), "utf-8");

        // 创建Template对象
        Template template = null;
        template = cfg.getTemplate(ftlName);
        template.setEncoding("utf-8");

        Map context = new HashMap();
        // 将json字符串加入数据模型
        context.put("getData", jsonDataString);

        // 输出流
        StringWriter writer = new StringWriter();
        // 将数据和模型结合生成html
        template.process(context, writer);
        // 获得html
        resultString = writer.toString();

        writer.close();
        return resultString;
    }

}

UserActionHtmlString.java Action代码如下：

package com.hsinghsu.test.action;

import java.util.List;

import net.sf.json.JSONArray;

import com.hsinghsu.test.dao.UserDao;
import com.hsinghsu.test.model.User;
import com.hsinghsu.test.util.FTL2String;
import com.opensymphony.xwork2.ActionSupport;

/**
 * 返回html流给前台
 * @author HsingHsu
 *
 */
public class UserActionHtmlString extends ActionSupport
{

    /**
     * 
     */
    private static final long serialVersionUID = 1006905813011288043L;

    public String execute() throws Exception
    {
        UserDao userDao = new UserDao();
        List uList = userDao.getUserList();

        // String jsonString =
        // "{'userList': [{'id': 0,'name': 'name0','age': 0},{'id': 1,'name': 'name1','age': 2},{'id': 2,'name': 'name2','age': 2},{'id': 3,'name': 'name3','age': 2},{'id': 4,'name': 'name4','age': 2},{'id': 5,'name': 'name5','age': 2},{'id': 6,'name': 'name6','age': 2},{'id': 7,'name': 'name7','age': 2},{'id': 8,'name': 'name8','age': 2},{'id': 9,'name': 'name1','age': 2}]}";

        String jsonString = JSONArray.fromObject(uList).toString();
        // jsonString = JSONObject.fromObject(uList).toString();

        System.out.println("json:" + jsonString);
        // print:[{"age":0,"id":0,"name":"name0"},{"age":2,"id":1,"name":"name1"},{"age":4,"id":2,"name":"name2"},{"age":6,"id":3,"name":"name3"},{"age":8,"id":4,"name":"name4"},{"age":10,"id":5,"name":"name5"},{"age":12,"id":6,"name":"name6"},{"age":14,"id":7,"name":"name7"},{"age":16,"id":8,"name":"name8"},{"age":18,"id":9,"name":"name9"}]

        String ftlPath = "/templates/";
        String ftlName = "htmlStringTemplate.ftl";

        String html = FTL2String.createHtmlString(ftlPath, ftlName, jsonString);
        System.out.println("html:" + html);

        return SUCCESS;
    }
}

struts.xml配置文件如下，注：用户可根据不同的业务请求，来将html流展现给用户

htmlStringTemplate.ftl文件配置如下：

<#assign data = getData?eval>

    
    <#list data as user>   
    
	
    <#-- 注：jsonString = "{'userList': [{'id':******
    <#list data.userList as user>   
    
	-->
	
   
    
   
        
id
   
        
name
  
        
age
    
    
   
        
${user.id}
   
        
${user.name}
        
${user.age}
    
	
   
        
${user.id}
   
        
${user.name}
        
${user.age}