5分钟学会Freemarker自定义标签(java后台宏)实现-进阶篇

                                freemarker自定义标签(java后台宏)实现 - 进阶篇

一、前言

       freemarker自定义标签( java后台宏 )实现。

              该篇文章对 BaseDirective / UserDirective进行封装 - (用于实际开发)。

       在此记录下，分享给大家。

 二、freemarker自定义标签(java后台宏)

1、pom文件 依赖引入

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.8.RELEASE</version>
        <relativePath />
    </parent>

    <dependencies>
        <!-- SpringBoot 测试 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <!-- SpringBoot 整合 Freemarker -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-freemarker</artifactId>
        </dependency>

        <!-- SpringBoot web组件 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- mybatis 支持 SpringBoot -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>

        <!-- mysql 驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.38</version>
        </dependency>

        <!-- 注解式 插入/构建/优雅代码 -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.4</version>
        </dependency>
    </dependencies>

2、 application.yml 新增配置

spring:
  http:
    encoding:
      force: true
      # 模板引擎编码为UTF-8
      charset: UTF-8
  freemarker:
    allow-request-override: false
    cache: false
    check-template-location: true
    charset: UTF-8
    content-type: text/html; charset=utf-8
    expose-request-attributes: false
    expose-session-attributes: false
    expose-spring-macro-helpers: false
    # 模板文件结尾.ftl
    suffix: .ftl
    # 模板文件目录
    template-loader-path: classpath:/templates
  datasource:
    url: jdbc:mysql://localhost:3306/yys_springboot_mybatis
    username: root
    password: 123456
    driver-class-name: com.mysql.jdbc.Driver
  mvc:   #静态文件
    static-path-pattern : /static/**

3、FreemarkerConfig.java

/**
 * Freemarker自定义指令(宏)
 *      Config
 * @author yys
 */
@Configuration
public class FreeMarkerConfig {

    @Autowired
    private freemarker.template.Configuration configuration;

    @Autowired
    private UserDirective userDirective;

    @PostConstruct
    public void setSharedVariable() {
        // userDirective即为页面上调用的标签名
        configuration.setSharedVariable("userDirective", userDirective);
    }

}

4、BaseDirective.java

/**
 * 所有自定义标签的父类，负责调用具体的子类方法
 *      Directive
 * @author yys
 */
public abstract class BaseDirective implements TemplateDirectiveModel {

    private String clazzPath = null;

    public BaseDirective(String targetClassPath) {
        clazzPath = targetClassPath;
    }

    private String getMethod(Map params) {
        return this.getParam(params, "method");
    }

    protected int getPageSize(Map params) {
        int pageSize = 10;
        String pageSizeStr = this.getParam(params, "pageSize");
        if (!StringUtils.isEmpty(pageSizeStr)) {
            pageSize = Integer.parseInt(pageSizeStr);
        }
        return pageSize;
    }

    private void verifyParameters(Map params) throws TemplateModelException {
        String permission = this.getMethod(params);
        if (permission == null || permission.length() == 0) {
            throw new TemplateModelException("The 'name' tag attribute must be set.");
        }
    }

    String getParam(Map params, String paramName) {
        Object value = params.get(paramName);
        return value instanceof SimpleScalar ? ((SimpleScalar) value).getAsString() : null;
    }

    private DefaultObjectWrapper getBuilder() {
        return new DefaultObjectWrapperBuilder(Configuration.VERSION_2_3_25).build();
    }

    private TemplateModel getModel(Object o) throws TemplateModelException {
        return this.getBuilder().wrap(o);
    }


    @Override
    public void execute(Environment environment, Map map, TemplateModel[] templateModels,
                        TemplateDirectiveBody templateDirectiveBody) throws TemplateException, IOException {
        this.verifyParameters(map);
        String funName = getMethod(map);
        Method method = null;
        try {
            Class clazz = Class.forName(clazzPath);
            method = clazz.getDeclaredMethod(funName, Map.class);
            if (method != null) {
                Object res = method.invoke(this, map);
                environment.setVariable(funName, getModel(res));
            }
        } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException | ClassNotFoundException e) {
            e.printStackTrace();
        }
        templateDirectiveBody.render(environment.getOut());
    }

}

5、UserDirective.java

/**
 * 用户管理
 *      Directive
 * @author yys
 */
@Component
public class UserDirective extends BaseDirective {

    @Autowired
    private UserService userService;

    public UserDirective() {
        super(UserDirective.class.getName());
    }

    /**
     * 自定义标签的方法
     * @param params
     * @return
     */
    public Object user(Map params) {
        return userService.getUserByName(params.get("name").toString());
    }

    public Object userList(Map params) {
        return userService.getUserList();
    }

}

6、UserEntity.java

/**
 * 用户管理
 *      Entity
 * @author yys
 */
@Data
public class UserEntity implements Serializable {

    private Long id;

    private String name;

    private Integer age;

    private Byte status;

    @JsonFormat(pattern="yyyy-MM-dd HH:mm:ss", timezone="GMT+8")
    private Date createTime;

    @JsonFormat(pattern="yyyy-MM-dd HH:mm:ss", timezone="GMT+8")
    private Date updateTime;

}

7、UserController.java

/**
 * 自定义指令(宏)
 *      Controller
 * @author yys
 */
@Controller
@RequestMapping("/user")
public class UserController {

    @RequestMapping("/list")
    public String userList(HttpServletRequest request, String name) {
        request.setAttribute("name", StringUtils.isEmpty(name) ? "yys" : name);
        return "user/list";
    }

}

8、UserService.java

/**
 * 用户管理
 *      Service
 * @author yys
 */
@Service
public class UserService {

    @Autowired
    private UserMapper userMapper;

    public boolean addUser(String userName, Integer age) {
        return userMapper.insert(userName, age) > 0 ? true : false;
    }

    public UserEntity getUserByName(String userName) {
        return userMapper.findByName(userName);
    }

    public List<UserEntity> getUserList() {
        return userMapper.findAll();
    }

}

9、UserMapper.java

/**
 * 用户管理
 *      Mapper
 * @author yys
 */
public interface UserMapper {

    @Select("SELECT id, user_name AS name, age, status, create_time AS createTime, update_time AS updateTime FROM yys_user WHERE user_name = #{name}")
    UserEntity findByName(@Param("name") String name);

    @Insert("INSERT INTO yys_user VALUES (NULL, #{name}, #{age}, 1, NOW(), NOW())")
    int insert(@Param("name") String name, @Param("age") Integer age);

    @Select("SELECT id, user_name AS name, age, status, create_time AS createTime, update_time AS updateTime FROM yys_user")
    List<UserEntity> findAll();

}

10、启动类

@SpringBootApplication
@MapperScan("com.yys.mapper")
public class YysApp {

    public static void main(String[] args) {
        SpringApplication.run(YysApp.class, args);
    }

}

11、list.ftl

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>一生猿，一世猿。</title>
</head>
<style>
    .table-div table{ border:1px solid black; }
    .table-div table td{ border:1px solid black; }
</style>
<body>
<div class="table-div">

    <@userDirective name='${name}'; user, userList>

        <#-- 通过名称获取用户宏 -->
        <table class="table" style="margin-bottom: 10px;">
            <thead>通过名称获取用户：</thead>
            <tbody>
            <tr>
                <td>花名</td>
                <td>年龄</td>
                <td>创建时间</td>
            </tr>
            <tr>
                <td>${user.name}</td>
                <td>${user.age}</td>
                <td>${user.createTime?datetime}</td>
                <#-- ?date：yyyy-MM-dd  ?time：HH:mm:ss  ?datetime：yyyy-MM-dd HH:mm:ss -->
            </tr>
            </tbody>
        </table>

        <#-- 获取用户列表宏 -->
        <table class="table">
            <thead>获取用户列表：</thead>
            <tbody>
            <tr>
                <td>花名</td>
                <td>年龄</td>
                <td>创建时间</td>
            </tr>
            <#if userList?? && userList?size gt 0>
                <#list userList as user>
                    <tr>
                        <td>${user.name}</td>
                        <td>${user.age}</td>
                        <td>${user.createTime?datetime}</td>
                    </tr>
                </#list>
            </#if>
            </tbody>
        </table>
    </@userDirective>

</div>
</body>
</html>

12、初始化sql文件

CREATE TABLE `yys_user` (
  `id` bigint(11) NOT NULL AUTO_INCREMENT COMMENT 'ID，自增列',
  `user_name` varchar(32) NOT NULL COMMENT '用户名',
  `age` int(11) NOT NULL COMMENT '用户年龄',
  `status` tinyint(2) NOT NULL DEFAULT '1' COMMENT '状态：-1-删除；1-正常；',
  `create_time` datetime NOT NULL COMMENT '创建时间',
  `update_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

INSERT INTO `yys_user` (`id`, `user_name`, `age`, `status`, `create_time`, `update_time`) VALUES ('1', 'yys', '18', '1', NOW(), NOW());
INSERT INTO `yys_user` (`id`, `user_name`, `age`, `status`, `create_time`, `update_time`) VALUES ('2', '洞人', '23', '1', NOW(), NOW());

13、测试

http://localhost:8080/user/list

  a、页面结果 - 如下图所示 ：

                       Now ~ ~ ~写到这里，就写完了，如果有幸帮助到你，请记得关注我，共同一起见证我们的成长。

最后

以上就是淡定面包为你收集整理的5分钟学会Freemarker自定义标签(java后台宏)实现-进阶篇的全部内容，希望文章能够帮你解决5分钟学会Freemarker自定义标签(java后台宏)实现-进阶篇所遇到的程序开发问题。

如果觉得靠谱客网站的内容还不错，欢迎将靠谱客网站推荐给程序员好友。