freemarker 用法总结-蒲公英云

freemarker 用法总结

freemarker 模板引擎解析对象

${user.userName!"默认值"}

freemarker 模板引擎取 Session 中取值

${Session.user.userName!"default value"}

freemarker 模板引擎遍历 list

<#if userLists?exists>
   <#list userLists as leaveobj>
      <tr>
         <td class="text-center">${leaveobj_index+1}</td>
         <td class="text-center">${leaveobj.userName!"设置默认值"}</td>
         <td class="text-center">${leaveobj.userAge!"设置默认值"}</td>
      </tr>     
   </#list>
</#if>

注意:无论是解析对象，还是遍历 list，都要设置默认值（即该值为空时的值），否则 freemarker 会报 The following has evaluated to null or missing 的错

以下以一个小 demo 为例，测试以上代码

项目框架使用 springboot

实体类

package com.freemark.bean;
public class User {
    private String userName;
    private Integer userAge;
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public Integer getUserAge() {
        return userAge;
    }
    public void setUserAge(Integer userAge) {
        this.userAge = userAge;
    }
}

controller 层

package com.freemark.controller;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.http.HttpSession;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
import com.freemark.bean.User;
@Controller
@RequestMapping("/freem")
public class DemoController {
    /**
     * 返回对象
     * @return
     */
    @RequestMapping("/user")
    public ModelAndView getUser(HttpSession session) {
        ModelAndView mav = new ModelAndView();
        User user = new User();
        user.setUserName("楚庄王");
        //user.setUserAge(25);
        session.setAttribute("user", user); // session中存值
        mav.addObject("user", user);
        mav.setViewName("user");
        return mav;
    }
    /**
     * 返回 list
     * @return
     */
    @RequestMapping("/user/list")
    public ModelAndView getUserList() {
        ModelAndView mav = new ModelAndView();
        List<User> list = new ArrayList<User>();
        User user1 = new User();
        user1.setUserName("楚庄王");
        user1.setUserAge(25);
        list.add(user1);
        User user2 = new User();
        user2.setUserName("齐桓公");
        user2.setUserAge(18);
        list.add(user2);
        User user3 = new User();
        user3.setUserName("晋文公");
        user3.setUserAge(60);
        list.add(user3);
        User user4 = new User();
        user4.setUserName("秦穆公");
        user4.setUserAge(55);
        list.add(user4);
        User user5 = new User();
        user5.setUserName("吴王阖闾");
        user5.setUserAge(27);
        list.add(user5);
        mav.addObject("userLists", list);
        mav.setViewName("userList");
        return mav;
    }
}

user.ftl 页面

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>freemarker解析对象</title>
</head>
<body>
     session中取值 ${Session.user.userName!"default value"}
      <br>
     ${user.userName!"默认值"}
     ${user.userAge!"30"}
</body>
</html>

userList.ftl 页面

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>freemarker遍历list</title>
</head>
<body>
    <table border="1">
        <tr>
          <td  class="text-center"><strong>序号</strong></td>
          <td  class="text-center"><strong>用户名</strong></td>
          <td  class="text-center"><strong>年龄</strong></td>
        </tr>
        <#if userLists?exists>
          <#list userLists as leaveobj>
            <tr>
                <td class="text-center">${leaveobj_index+1}</td>
                <td class="text-center">${leaveobj.userName!"设置默认值"}</td>
                <td class="text-center">${leaveobj.userAge!"设置默认值"}</td>
            </tr>     
          </#list>
        </#if>
     </table>
</body>
</html>