FreeMarker

渲染字符串模板

 package com.example;

import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
import java.io.Writer;
import java.util.Arrays;
import java.util.Map;

import com.alibaba.fastjson.JSON;

import freemarker.cache.StringTemplateLoader;
import freemarker.template.Configuration;
import freemarker.template.Template;
import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.ResourceLoader;

/**
 * @author whilst
 * @date 2017/04/08
 */
public class FreeMarkerUtils {
    private static final Logger logger = LoggerFactory.getLogger(MessageServiceImpl.class);

    private Configuration freeMarkerConfig;

    @Autowired
    private ResourceLoader resourceLoader;

    private void initFreeMarkerTemplate() {
        synchronized (this) {
            if (null != freeMarkerConfig) {
                return;
            }
            freeMarkerConfig = new Configuration(Configuration.VERSION_2_3_25);

            StringTemplateLoader stringLoader = new StringTemplateLoader();
            Arrays.asList("classpath:template/template1.ftl", "classpath:template/template2.ftl").forEach(filepath -> {
                try {
                    InputStream inputStream = resourceLoader.getResource(filepath).getInputStream();
                    String content = IOUtils.toString(inputStream, "UTF-8");
                    stringLoader.putTemplate(filepath, content);
                } catch (IOException e) {
                    logger.error("加载模板文件出错, filepath: [" + filepath + "], 出错原因: ", e);
                }
            });

            freeMarkerConfig.setTemplateLoader(stringLoader);
        }
    }

    private String renderTemplate(String templateName, Map<String, Object> model) {
        initFreeMarkerTemplate();

        Writer out = new StringWriter(10480);
        try {
            Template tpl = freeMarkerConfig.getTemplate(templateName);
            tpl.process(model, out);
        } catch (Exception e) {
            String error = "渲染模板出错, template: [" + templateName + "], model: [" + JSON.toJSONString(model) + "]";
            logger.error(error, e);
            throw new IllegalArgumentException(error, e);
        }

        return out.toString();
    }
}