freemarker 用法总结

深藏阁楼爱情的钟 2022-04-02 03:21 320阅读 0赞

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>

注意： $\{leaveobj\_index+1\} 为 freemarker 模板自带的序号自增， +1 为从 1 开始；$\{leaveobj\_index\} 为从 0 开始

测试

访问 [http://localhost:8080/freem/user][http_localhost_8080_freem_user]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dzanp6Y2Jx_size_16_color_FFFFFF_t_70][]

访问 [http://localhost:8080/freem/user/list][http_localhost_8080_freem_user_list]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dzanp6Y2Jx_size_16_color_FFFFFF_t_70 1][]

[http_localhost_8080_freem_user]: http://localhost:8080/freem/user
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dzanp6Y2Jx_size_16_color_FFFFFF_t_70]: /images/20220402/957f37f258924822aee261587aaf3723.png
[http_localhost_8080_freem_user_list]: http://localhost:8080/freem/user/list
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dzanp6Y2Jx_size_16_color_FFFFFF_t_70 1]: /images/20220402/c159f7228b884632b73df6d62c1be08a.png