微服务现在最流行的莫过于springboot，官方推荐两种模板语言，freemarker和thymeleaf，本文只介绍thymeleaf中如何定义全局常量。百度一搜thymeleaf的全局常量定义，都是让把常量写在“message_*”文件中，当然，做国际化的时候这个没问题 ，可是随着现在微服务大行其道，有很多不是国际化的东西需要定义，例如服务A调用服务B，这时候肯定要在A中配置B的url，这时候再写入message明显不合适了。

惯例先上思路

在模板解析时候就将常量写入，重写模板解析配置方法。看springboot源码

public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {
      /**
     * {@inheritDoc}
     * <p>This implementation is empty.
     */
    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
    }
｝

目测应该是重写这货就可以了，talk is cheap，show me the code

动手重写

1.现在Application.properties中定义两个常量,用于文件上传和预览

upload.path=http://localhost:9091/accessory/upload
image.view.path=http://localhost:9091/accessory/open?id=

2.重写configureViewResolvers(ViewResolverRegistry registry)

   @Resource(name="thymeleafViewResolver")
    private ThymeleafViewResolver thymeleafViewResolver;

    @Value("${upload.path}")
    private String defaultUploadPath;

    @Value("${image.view.path}")
    private String defaultImageViewPath;

    @Override
    public void configureViewResolvers(ViewResolverRegistry registry) {
        if (thymeleafViewResolver != null) {
            Map<String, Object> vars = new HashMap<>(8);
            vars.put("uploadPath", defaultUploadPath);
            vars.put("defaultImageViewPath", defaultImageViewPath);
            thymeleafViewResolver.setStaticVariables(vars);
        }
        super.configureViewResolvers(registry);
    }

3.模板上使用
html中

<img src="/images/default-mem.png" th:src="${defaultImageViewPath+user.photo}" alt="" >

js中
写法比较奇怪， /<![CDATA[/ 中间写定义的全局js常量 /]]>/

    <script th:inline="javascript">
        /*<![CDATA[*/
        var basePath='http://www.baidu.com';
        var uploadPath=[[${uploadPath}]];
        var defaultImageViewPath=[[${defaultImageViewPath}]];
        /*]]>*/
    </script>

就是酱紫。