SpringBoot整合Velocity实现代码预览和文件生成

╰半夏微凉° 2022-12-17 08:54 144阅读 0赞

这里做一个简单的示例DEMO，实现一键打包zip，提供一种解决方案，实际需求可以按需所改，代码就三四个文件不上传上来了，下面贴出完整代码：

文件目录如下：

![20201023110208785.png][]

**实体类User.java**

省略 getter 和 setter 方法

package com.fun.demo.model;
    
    /**
     * @author MrDJun 2020/10/21
     */
    public class User {
        private Integer age;
        private String name;
    
        public User(Integer age, String name) {
            this.age = age;
            this.name = name;
        }
    
        public User(){}
    }

** VelocityUtils.java **

package com.fun.demo.tool;
    
    import com.fun.demo.model.User;
    import org.apache.velocity.Template;
    import org.apache.velocity.VelocityContext;
    import org.apache.velocity.app.Velocity;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.apache.commons.io.IOUtils;
    
    import java.io.ByteArrayOutputStream;
    import java.io.IOException;
    import java.io.StringWriter;
    import java.util.Properties;
    import java.util.zip.ZipEntry;
    import java.util.zip.ZipOutputStream;
    
    /**
     * @author MrDJun 2020/10/21
     */
    public class VelocityUtils {
        private final static Logger log = LoggerFactory.getLogger(VelocityUtils.class);
    
        public static String previewCode() {
            initVelocity();
            User user = new User(18, "mrdjun");
            VelocityContext context = VelocityUtils.prepareContext(user);
            StringWriter sw = new StringWriter();
            Template tpl = Velocity.getTemplate("vm/xml/article.xml.vm", "UTF-8");
            tpl.merge(context, sw);
            return sw.toString();
        }
    
        public static byte[] downloadCode() {
            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
            ZipOutputStream zip = new ZipOutputStream(outputStream);
            generatorCode(zip);
            IOUtils.closeQuietly(zip);
            return outputStream.toByteArray();
        }
    
        public static void generatorCode(ZipOutputStream zip) {
            User user = new User(18, "mrdjun");
            initVelocity();
            VelocityContext context = VelocityUtils.prepareContext(user);
    
            StringWriter sw = new StringWriter();
            Template tpl = Velocity.getTemplate("vm/xml/article.xml.vm", "UTF-8");
            tpl.merge(context, sw);
            try {
                // 添加到zip
                zip.putNextEntry(new ZipEntry("article.xml"));
                IOUtils.write(sw.toString(), zip, "UTF-8");
                IOUtils.closeQuietly(sw);
                zip.flush();
                zip.closeEntry();
            } catch (IOException e) {
                log.error("渲染模板失败：{0}", e);
            }
    
        }
    
        public static VelocityContext prepareContext(User user) {
            VelocityContext velocityContext = new VelocityContext();
            velocityContext.put("age", user.getAge());
            velocityContext.put("name", user.getName());
            return velocityContext;
        }
    
        public static void initVelocity() {
            Properties p = new Properties();
            try {
                // 加载classpath目录下的vm文件
                p.setProperty("file.resource.loader.class", "org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader");
                // 定义字符集
                p.setProperty(Velocity.ENCODING_DEFAULT, "UTF-8");
                p.setProperty(Velocity.OUTPUT_ENCODING, "UTF-8");
                // 初始化Velocity引擎，指定配置Properties
                Velocity.init(p);
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
    }

**CodeController.java**

package com.fun.demo.controller;
    
    import com.fun.demo.tool.VelocityUtils;
    import org.apache.commons.io.IOUtils;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    /**
     * @author MrDJun 2020/10/21
     */
    @RestController
    public class CodeController {
    
        @RequestMapping("/download")
        public void download(HttpServletResponse response) throws IOException {
            byte[] data = VelocityUtils.downloadCode();
            genCode(response, data);
        }
    
        /**
         * 生成zip文件
         */
        private void genCode(HttpServletResponse response, byte[] data) throws IOException {
            response.reset();
            response.setHeader("Content-Disposition", "attachment; filename=\"fun.zip\"");
            response.addHeader("Content-Length", "" + data.length);
            response.setContentType("application/octet-stream; charset=UTF-8");
            IOUtils.write(data, response.getOutputStream());
        }
    }

在创建一个SpringBoot的启动类

在resources下面创建一个vm文件夹，**article.xml.vm**

<?xml version="1.0" encoding="utf-8"?>
    <DOCUMENT>
        我叫${name}，今年${age}岁
    </DOCUMENT>

**pom.xml**

我这里的全部依赖如下，按需所取：

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>2.1.5.RELEASE</version>
            <relativePath/>
        </parent>
    
        <groupId>com.fun</groupId>
        <artifactId>demo</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>demo</name>
        <description>Demo project for Spring Boot</description>
    
        <properties>
            <java.version>1.8</java.version>
        </properties>
    
        <dependencies>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context-support</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>org.apache.commons</groupId>
                <artifactId>commons-lang3</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>commons-io</groupId>
                <artifactId>commons-io</artifactId>
                <version>2.5</version>
            </dependency>
    
            
            <dependency>
                <groupId>org.apache.velocity</groupId>
                <artifactId>velocity</artifactId>
                <version>1.7</version>
            </dependency>
    
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-test</artifactId>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>
    
    </project>

[20201023110208785.png]: /images/20221122/58eabdc8a4484bb9a24cbd6df76f6b26.png