Freemarker与Spring设置自定义函数

绝地灬酷狼 2022-07-11 09:11 315阅读 0赞

以前经常用freemarker，但是从来没有系统的学习过，最近有时间了，找到资料学习一下，官方文档下载地址：[打开下载][Link 1]

freemarker会用并不难，本篇博客是分享freemarker和spring如何结合使用，代码全部是参考上家公司的经理的，前人栽树后人乘凉

以下两种方法，都是假设已经与springmvc整合完毕

## 自定义函数（普通） ##

##### 1：实现TemplateMethodModelEx #####

package com.mall.web.template.method;
    
    import com.fengyong.base.rely.ResultPoBean;
    import com.product.po.user.base.BaseSysUserPo;
    import com.product.service.user.UserService;
    import freemarker.template.TemplateMethodModelEx;
    import freemarker.template.TemplateModelException;
    import org.springframework.beans.factory.annotation.Autowired;
    import java.util.List;
    
    /**
     * 描述:
     *
     * @author fengyong
     * @date 2017/1/22.
     */
    public class GetUserMethod implements TemplateMethodModelEx {
        @Autowired
        private UserService userService;
        @Override
        public Object exec(List arguments) throws TemplateModelException {
            ResultPoBean<BaseSysUserPo> resultPoBean = userService.getSysUserPo(new Long(arguments.get(0).toString()));
            return resultPoBean.getValue();
        }
    }

##### 2：配置文件 #####

<bean id="freeMarkerViewResolver" class="org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver">
            <property name="suffix" value=".ftl"/>
            <property name="contentType" value="text/html; charset=UTF-8" />
            <property name="exposeRequestAttributes" value="true" />
            <property name="exposeSessionAttributes" value="false" />
            <property name="exposeSpringMacroHelpers" value="true" />
        </bean>
    
        <bean id="freemarkerConfig"
              class="org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer">
            <property name="templateLoaderPath" value="/WEB-INF/ftl"/>
            <property name="freemarkerSettings">
                <props>
                    <prop key="defaultEncoding">utf-8</prop>
                    <prop key="url_escaping_charset">utf-8</prop>
                    <prop key="template_update_delay">0</prop>
                    <prop key="locale">zh_CN</prop>
                    <prop key="number_format">0.######</prop>
                    <prop key="boolean_format">true,false</prop>
                    <prop key="datetime_format">yyyy-MM-dd HH:mm:ss</prop>
                    <prop key="date_format">yyyy-MM-dd</prop>
                    <prop key="time_format">HH:mm:ss</prop>
                    <prop key="whitespace_stripping">true</prop>
                    <prop key="auto_import">/app/auto_import.ftl as p</prop>
                </props>
            </property>
            <property name="freemarkerVariables">
                <map>
                    
                    <entry key="base" value="#{servletContext.contextPath}"/>
                    <entry key="getUserMethod" value-ref="getUserMethod"/>
                </map>
            </property>
        </bean>
    
        <bean id="getUserMethod" class="com.mall.web.template.method.GetUserMethod"/>

##### 3：ftl页面中使用 #####

<#assign getUserMethod= getUserMethod("1")/>
    ${getUserMethod}

## 自定义函数（完美整合） ##

上面的方法是很多网上资料中都有得，但是有一定的缺点，如果有很多歌方法，那配置文件中的freemarkerVariables会无限增大，配置起来很麻烦，接下来，我会一步步解析。

##### 1：首先看freemarkerVariables中定义的函数去了哪里 #####

public void setFreemarkerVariables(Map<String, Object> variables) {
        this.freemarkerVariables = variables;
    }

##### 2：查看freemarkerVariables去了哪里 #####

public class FreeMarkerConfigurationFactory {
        protected final Log logger = LogFactory.getLog(this.getClass());
        private Resource configLocation;
        private Properties freemarkerSettings;
        private Map<String, Object> freemarkerVariables;

##### 3：在整个FreeMarkerConfigurationFactory里面，只有一处用到了freemarkerVariables。看下面代码 #####

public Configuration createConfiguration() throws IOException, TemplateException {
        Configuration config = this.newConfiguration();
        Properties props = new Properties();
        if(this.configLocation != null) {
            if(this.logger.isInfoEnabled()) {
                this.logger.info("Loading FreeMarker configuration from " + this.configLocation);
            }
    
            PropertiesLoaderUtils.fillProperties(props, this.configLocation);
        }
    
        if(this.freemarkerSettings != null) {
            props.putAll(this.freemarkerSettings);
        }
    
        if(!props.isEmpty()) {
            config.setSettings(props);
        }
    
        if(!CollectionUtils.isEmpty(this.freemarkerVariables)) {
            config.setAllSharedVariables(new SimpleHash(this.freemarkerVariables, config.getObjectWrapper()));
        }

##### 4：这时我们知道了自定义函数被放进了config，继续看这个方法 #####

public void setAllSharedVariables(TemplateHashModelEx hash) throws TemplateModelException {
        TemplateModelIterator keys = hash.keys().iterator();
        TemplateModelIterator values = hash.values().iterator();
        while(keys.hasNext())
        {
            setSharedVariable(((TemplateScalarModel)keys.next()).getAsString(), values.next());
        }
    }

public void setSharedVariable(String name, TemplateModel tm) {
        Object replaced = sharedVariables.put(name, tm);
        if (replaced != null && rewrappableSharedVariables != null) {
            rewrappableSharedVariables.remove(name);
        }
    }

##### ok，现在看到了自定义函数都被放到了sharedVariables里面，那么我们只要获取config，调用setSharedVariable把自定义函数放进去，我们就可以不用无限配置了。 #####

##### 5：继续看config，从FreeMarkerConfigurationFactory的子FreeMarkerConfigurer（配置文件中出现过）可以看到config的去处 #####

private Configuration configuration;
    private TaglibFactory taglibFactory;
    
    public FreeMarkerConfigurer() {
    }
    
    public void setConfiguration(Configuration configuration) {
        this.configuration = configuration;
    }
    
    public void setServletContext(ServletContext servletContext) {
        this.taglibFactory = new TaglibFactory(servletContext);
    }
    
    public void afterPropertiesSet() throws IOException, TemplateException {
        if(this.configuration == null) {
            this.configuration = this.createConfiguration();
        }
    
    }

##### 6：现在知道了config，也知道了如何往sharedVariables里面设置自定义函数，就可以开工了。 #####

1：创建注解，用于标注自定义方法的类

package com.mall.web.template.method;
    
    import org.springframework.stereotype.Component;
    
    import java.lang.annotation.ElementType;
    import java.lang.annotation.Retention;
    import java.lang.annotation.RetentionPolicy;
    import java.lang.annotation.Target;
    
    /** * Created by fengyong on 2017/1/22. */ @Target(value = ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    @Component
    public @interface FreemarkerComponent {
        String value() default "";
    }

2：创建MdFreeMarkerConfigurer继承FreeMarkerConfigurer，并且ApplicationContextAware，实现ApplicationContextAware是为了获取ApplicationContext，并通过ApplicationContext获取注解和所注解的类

package com.mall.web.template.method;
    
    import freemarker.template.Configuration;
    import freemarker.template.TemplateException;
    import org.springframework.beans.BeansException;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
    import org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer;
    
    import java.io.IOException;
    import java.util.Map;
    
    /** * Created by fengyong on 2017/1/22. */ public class MdFreeMarkerConfigurer extends FreeMarkerConfigurer implements ApplicationContextAware {
        private ApplicationContext applicationContext;
    
        public void afterPropertiesSet() throws IOException, TemplateException {
            super.afterPropertiesSet();
            Map<String, Object> map = applicationContext.getBeansWithAnnotation(FreemarkerComponent.class);
            Configuration configuration = this.getConfiguration();
            for (String key : map.keySet()) {
                configuration.setSharedVariable(key, map.get(key));
            }
        }
    
        @Override
        public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
            this.applicationContext = applicationContext;
        }
    }

解释一下afterPropertiesSet，这个方法是在实例化bean的时候调用。

3：写一个自定义方法

package com.mall.web.template.method;
    
    import com.fengyong.base.rely.ResultPoBean;
    import com.product.po.user.base.BaseSysUserPo;
    import com.product.service.user.UserService;
    import freemarker.template.TemplateMethodModelEx;
    import freemarker.template.TemplateModelException;
    import org.springframework.beans.factory.annotation.Autowired;
    import java.util.List;
    
    /** * 描述: * * @author fengyong * @date 2017/1/22. */ @FreemarkerComponent("getUserMethod")
    public class GetUserMethod implements TemplateMethodModelEx {
        @Autowired
        private UserService userService;
        @Override
        public Object exec(List arguments) throws TemplateModelException {
            ResultPoBean<BaseSysUserPo> resultPoBean = userService.getSysUserPo(new Long(arguments.get(0).toString()));
            return resultPoBean.getValue();
        }
    }

4：接下来需要修改<context:component-scan base-package="com.\*" />，让spring可以扫描到所有的自定义方法类，这样ApplicationContext才可以获得这个注解和所注解的类，之后每次写自定义方法，都只需要加一个@FreemarkerComponent("\*\*\*\*")就可以了，不需要再配置了。

[Link 1]: http://download.csdn.net/detail/spiniper/5266040