spring boot中使用freemarker模板引擎技術，spring boot中提供了一些預設的配置。預設配置如下所示：

本文只探討freemarker中模板路徑的設定方式，其他配置，請注意檢視後續文章。

# FREEMARKER (FreeMarkerAutoConfiguration)
spring.freemarker.allow-request-override=false # Set whether HttpServletRequest attributes are allowed to override (hide) controller generated model attributes of the same name.
spring.freemarker.allow-session-override=false
 
 # Set whether HttpSession attributes are allowed to override (hide) controller generated model attributes of the same name.
spring.freemarker.cache=false # Enable template caching.
spring.freemarker.charset=UTF-8 # Template encoding.
spring.freemarker.check-template-location=true # Check that the templates location exists.
spring.freemarker.content-type=text/html # Content-Type value.
spring.freemarker.enabled=true
 
 # Enable MVC view resolution for this technology.
spring.freemarker.expose-request-attributes=false # Set whether all request attributes should be added to the model prior to merging with the template.
spring.freemarker.expose-session-attributes=false # Set whether all HttpSession attributes should be added to the model prior to merging with the template.
spring.freemarker.expose-spring-macro-helpers=true
 
 # Set whether to expose a RequestContext for use by Spring's macro library, under the name "springMacroRequestContext".
spring.freemarker.prefer-file-system-access=true # Prefer file system access for template loading. File system access enables hot detection of template changes.
spring.freemarker.prefix= # Prefix that gets prepended to view names when building a URL.
spring.freemarker.request-context-attribute= # Name of the RequestContext attribute for all views.
spring.freemarker.settings.*= # Well-known FreeMarker keys which will be passed to FreeMarker's Configuration.
spring.freemarker.suffix= # Suffix that gets appended to view names when building a URL.
spring.freemarker.template-loader-path=classpath:/templates/ # Comma-separated list of template paths.
spring.freemarker.view-names= # White list of view names that can be resolved.

如上所示，您可以在spring boot的預設配置檔案中設定模板路徑（spring boot預設讀取的配置檔案為：application.properties，當然還有其他的讀取方式，如果想了解這方面的文章，請檢視後續文章）

spring.freemarker.template-loader-path=classpath:/templates/ # Comma-separated list of template paths.

此種配置，只能讀取classpath下的路徑。如果想要讀取其他路徑則要重寫freemarker的預設配置，在spring boot中，你可以這樣做：

@Configuration
public class TemplateLoader extends WebMvcConfigurerAdapter {
    @Bean
    public ViewResolver viewResolver() {
        FreeMarkerViewResolver resolver = new FreeMarkerViewResolver();
        resolver.setCache(true);
        resolver.setPrefix("");
        resolver.setSuffix(".ftl");
        resolver.setContentType("text/html; charset=UTF-8");
        return resolver;
    }

    @Bean
    public FreeMarkerConfigurer freemarkerConfig() throws IOException, TemplateException {
        FreeMarkerConfigurer configurer = new FreeMarkerConfigurer();
        configurer.setTemplateLoaderPaths("file:絕對路徑","http://www.xxx.com/");
        configurer.setDefaultEncoding("UTF-8");
        return configurer;
    }

}

如程式碼所示，在此處，你可以設定多個freemarker路徑，當然越靠前的路徑權重越高，系統會在讀取第一個失敗的情況下，會繼續讀取第二個路徑。

在此處，你可以有三種方式讀取模板路徑

第一種：classpath:/static/

第二種：file:絕對路徑

第三種：http://www.xxx.com

其中第一種和第二種是統一型別，但是，第一種只能讀取系統配置檔案路徑，第二種只能讀取絕對路徑。第三種則可以讀取ftp檔案

關於setTemplateLoaderPaths的方法，在原始碼中的解釋，我們可以看一下：

/**
	 * Set multiple Freemarker template loader paths via Spring resource locations.
	 * <p>When populated via a String, standard URLs like "file:" and "classpath:"
	 * pseudo URLs are supported, as understood by ResourceEditor. Allows for
	 * relative paths when running in an ApplicationContext.
	 * <p>Will define a path for the default FreeMarker template loader.
	 * If a specified resource cannot be resolved to a {@code java.io.File},
	 * a generic SpringTemplateLoader will be used, without modification detection.
	 * <p>To enforce the use of SpringTemplateLoader, i.e. to not resolve a path
	 * as file system resource in any case, turn off the "preferFileSystemAccess"
	 * flag. See the latter's javadoc for details.
	 * <p>If you wish to specify your own list of TemplateLoaders, do not set this
	 * property and instead use {@code setTemplateLoaders(List templateLoaders)}
	 * @see org.springframework.core.io.ResourceEditor
	 * @see org.springframework.context.ApplicationContext#getResource
	 * @see freemarker.template.Configuration#setDirectoryForTemplateLoading
	 * @see SpringTemplateLoader
	 */
	public void setTemplateLoaderPaths(String... templateLoaderPaths) {
		this.templateLoaderPaths = templateLoaderPaths;
	}

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