使用javaconfig配置freemarker

 package com.yy.config;

 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
 import org.springframework.web.servlet.config.annotation.EnableWebMvc;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
 import org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer;
 import org.springframework.web.servlet.view.freemarker.FreeMarkerView;
 import org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver;

 import java.util.Properties;

 /**
  * 配置上下文加载需要的bean
  * 包含Web组件的bean,如控制器、视图解析器、处理器映射
  * User : liuhuangyinying
  * Date : 2017-03-21 15:48
  */
 @Configuration
 @EnableWebMvc
 @ComponentScan("com.yy") // 启动组件扫描
 public class WebConfig extends WebMvcConfigurerAdapter{

     /**
      * 配置静态文件处理
      */
     @Override
     public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
         configurer.enable("/WEB-INF/static/");
     }

     /**
      * 配置freemarker视图解析器
      */
     @Bean
     public ViewResolver viewResolver(){
         FreeMarkerViewResolver viewResolver = new FreeMarkerViewResolver();
         viewResolver.setViewClass(FreeMarkerView.class);
         viewResolver.setCache(false);
         viewResolver.setPrefix("/WEB-INF/template/");
         viewResolver.setSuffix(".ftl");
         viewResolver.setContentType("text/html;charset=utf-8");
         viewResolver.setExposeRequestAttributes(true);
         viewResolver.setExposeSessionAttributes(true);
         viewResolver.setExposeSpringMacroHelpers(true);
         viewResolver.setRequestContextAttribute("rc");
         return viewResolver;
     }

     @Bean
     public FreeMarkerConfigurer freeMarkerConfigurer(){
         FreeMarkerConfigurer freeMarkerConfigurer = new FreeMarkerConfigurer();
         freeMarkerConfigurer.setTemplateLoaderPath("/");
         freeMarkerConfigurer.setDefaultEncoding("UTF-8");
         Properties properties = new Properties();
         properties.put("template_update_delay",10);
         properties.put("defaultEncoding","UTF-8");
         properties.put("url_escaping_charset","UTF-8");
         properties.put("locale","zh_CN");
         properties.put("boolean_format","true,false");
         properties.put("time_format","HH:mm:ss");
         properties.put("datetime_format","yyyy-MM-dd HH:mm:ss");
         properties.put("date_format","yyyy-MM-dd");
         properties.put("number_format","#,###.##");
         properties.put("whitespace_stripping","true");
         properties.put("classic_compatible","true");
         freeMarkerConfigurer.setFreemarkerSettings(properties);
         return freeMarkerConfigurer;
     }
 }

配置后启动项目，项目居然报错

居然是空指针错误，那么就只能设置断点调试，看看是否缺少配置什么属性。

跟踪到这一步的时候发现，这里抛出的异常，那么继续往下调试：

进入props.setProperty方法，会发现进入到java.util.Properties类报错：

什么鬼，只要不是String类型就设置为null，也就是说不支持int和boolean类型。

也就是说这里的value都必须加上双引号。不是经典的java包就是百分百可以信任的，遇到问题仍然要看源码才可以解决问题。

错误提示特别是空指针不一定是根源，断点真是个好东西。Love  Love Love