简介

在项目中，存在传递超大 json 数据的场景。直接传输超大 json 数据的话，有以下两个弊端

占用网络带宽，而有些云产品就是按照带宽来计费的，间接浪费了钱传输数据大导致网络传输耗时较长 为了避免直接传输超大 json 数据，可以对 json 数据进行 Gzip 压缩后，再进行网络传输。请求头添加 Content-Encoding 标识，传输的数据进行过压缩Servlet Filter 拦截请求，对压缩过的数据进行解压HttpServletRequestWrapper 包装，把解压的数据写入请求体pom.xml 引入依赖

<project xmlns="; xmlns:xsi="; xsi:schemaLocation=" ;> <modelVersion>4.0.0</modelVersion> <groupId>com.olive</groupId> <artifactId>request-uncompression</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>request-uncompression</name> <url>;/url> <parent>  <groupId>org.springframework.boot</groupId>  <artifactId>spring-boot-starter-parent</artifactId>  <version>2.5.14</version>  <relativePath /> <!-- lookup parent from repository --> </parent> <properties>  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>  <maven.compiler.source>8</maven.compiler.source>  <maven.compiler.target>8</maven.compiler.target> </properties> <dependencies>  <dependency>   <groupId>org.springframework.boot</groupId>   <artifactId>spring-boot-starter-test</artifactId>   <scope>test</scope>  </dependency>  <dependency>   <groupId>org.projectlombok</groupId>   <artifactId>lombok</artifactId>  </dependency>  <dependency>      <groupId>org.springframework.boot</groupId>      <artifactId>spring-boot-starter-web</artifactId>  </dependency>  <dependency>   <groupId>com.alibaba.fastjson2</groupId>   <artifactId>fastjson2</artifactId>   <version>2.0.14</version>  </dependency>    <dependency>   <groupId>commons-io</groupId>   <artifactId>commons-io</artifactId>   <version>2.9.0</version>  </dependency> </dependencies></project>

GzipUtils 类提供压缩解压相关方法

package com.olive.utils;import com.alibaba.fastjson2.JSON;import com.olive.vo.ArticleRequestVO;import lombok.extern.slf4j.Slf4j;import org.apache.commons.io.FileUtils;import java.io.*;import java.util.zip.GZIPInputStream;import java.util.zip.GZIPOutputStream;@Slf4jpublic class GzipUtils {    private static final String GZIP_ENCODE_UTF_8 = "UTF-8";    /**     * 字符串压缩为GZIP字节数组     *     * @param str     * @return     */    public static byte[] compress(String str) {        return compress(str, GZIP_ENCODE_UTF_8);    }    /**     * 字符串压缩为GZIP字节数组     *     * @param str     * @param encoding     * @return     */    public static byte[] compress(String str, String encoding) {        if (str == null || str.length() == 0) {            return null;        }        ByteArrayOutputStream out = new ByteArrayOutputStream();        GZIPOutputStream gzip = null;        try {            gzip = new GZIPOutputStream(out);            gzip.write(str.getBytes(encoding));        } catch (IOException e) {           log.error("compress>>", e);        }finally {            if(gzip!=null){                try {                    gzip.close();                } catch (IOException e) {                }            }        }        return out.toByteArray();    }    /**     * GZIP解压缩     *     * @param bytes     * @return     */    public static byte[] uncompress(byte[] bytes) {        if (bytes == null || bytes.length == 0) {            return null;        }        ByteArrayOutputStream out = new ByteArrayOutputStream();        ByteArrayInputStream in = new ByteArrayInputStream(bytes);        GZIPInputStream unGzip = null;        try {            unGzip = new GZIPInputStream(in);            byte[] buffer = new byte[256];            int n;            while ((n = unGzip.read(buffer)) >= 0) {                out.write(buffer, 0, n);            }        } catch (IOException e) {            log.error("uncompress>>", e);        }finally {            if(unGzip!=null){                try {                    unGzip.close();                } catch (IOException e) {                }            }        }        return out.toByteArray();    }    /**     * 解压并返回String     *     * @param bytes     * @return     */    public static String uncompressToString(byte[] bytes) throws IOException {        return uncompressToString(bytes, GZIP_ENCODE_UTF_8);    }    /**     * @param bytes     * @return     */    public static byte[] uncompressToByteArray(byte[] bytes) throws IOException {        return uncompressToByteArray(bytes, GZIP_ENCODE_UTF_8);    }    /**     * 解压成字符串     *     * @param bytes    压缩后的字节数组     * @param encoding 编码方式     * @return 解压后的字符串     */    public static String uncompressToString(byte[] bytes, String encoding) throws IOException {        byte[] result = uncompressToByteArray(bytes, encoding);        return new String(result);    }    /**     * 解压成字节数组     *     * @param bytes     * @param encoding     * @return     */    public static byte[] uncompressToByteArray(byte[] bytes, String encoding) throws IOException {        if (bytes == null || bytes.length == 0) {            return null;        }        ByteArrayOutputStream out = new ByteArrayOutputStream();        ByteArrayInputStream in = new ByteArrayInputStream(bytes);        GZIPInputStream unGzip = null;        try {            unGzip = new GZIPInputStream(in);            byte[] buffer = new byte[256];            int n;            while ((n = unGzip.read(buffer)) >= 0) {                out.write(buffer, 0, n);            }            return out.toByteArray();        } catch (IOException e) {            log.error("uncompressToByteArray>>", e);            throw new IOException("解压缩失败！");        }finally {            if(unGzip!=null){                unGzip.close();            }        }    }    /**     * 将字节流转换成文件     *     * @param filename     * @param data     * @throws Exception     */    public static void saveFile(String filename, byte[] data) throws Exception {        FileOutputStream fos = null;        try {            if (data != null) {                String filepath = "/" + filename;                File file = new File(filepath);                if (file.exists()) {                    file.delete();                }                fos = new FileOutputStream(file);                fos.write(data, 0, data.length);                fos.flush();                System.out.println(file);            }        }catch (Exception e){            throw e;        }finally {            if(fos!=null){                fos.close();            }        }    }}

UnZipRequestWrapper 读取输入流，然进行解压；解压完后，再把解压出来的数据封装到输入流中。

package com.olive.filter;import com.olive.utils.GzipUtils;import lombok.extern.slf4j.Slf4j;import javax.servlet.ReadListener;import javax.servlet.ServletInputStream;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;import java.io.*;/** *  Json String 经过压缩后保存为二进制文件 -> 解压缩后还原成 Jso nString转换成byte[]写回body中 */@Slf4jpublic class UnZipRequestWrapper extends HttpServletRequestWrapper {    private final byte[] bytes;    public UnZipRequestWrapper(HttpServletRequest request) throws IOException {        super(request);        try (BufferedInputStream bis = new BufferedInputStream(request.getInputStream());             ByteArrayOutputStream baos = new ByteArrayOutputStream()) {            final byte[] body;            byte[] buffer = new byte[1024];            int len;            while ((len = bis.read(buffer)) > 0) {                baos.write(buffer, 0, len);            }            body = baos.toByteArray();            if (body.length == 0) {                log.info("Body无内容，无需解压");                bytes = body;                return;            }            this.bytes = GzipUtils.uncompressToByteArray(body);        } catch (IOException ex) {            log.error("解压缩步骤发生异常！", ex);            throw ex;        }    }    @Override    public ServletInputStream getInputStream() throws IOException {        final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(bytes);        return new ServletInputStream() {            @Override            public boolean isFinished() {                return false;            }            @Override            public boolean isReady() {                return false;            }            @Override            public void setReadListener(ReadListener readListener) {            }            public int read() throws IOException {                return byteArrayInputStream.read();            }        };    }    @Override    public BufferedReader getReader() throws IOException {        return new BufferedReader(new InputStreamReader(this.getInputStream()));    }}

GzipFilter 拦截器根据请求头是否包含Content-Encoding=application/gzip，如果包含就对数据进行解压；否则就直接放过。

package com.olive.filter;import lombok.extern.slf4j.Slf4j;import org.springframework.stereotype.Component;import javax.servlet.*;import javax.servlet.http.HttpServletRequest;import java.io.IOException;/** * 解压filter */@Slf4j@Componentpublic class GzipFilter implements Filter {    private static final String CONTENT_ENCODING = "Content-Encoding";    private static final String CONTENT_ENCODING_TYPE = "application/gzip";    @Override    public void init(FilterConfig filterConfig) throws ServletException {        log.info("init GzipFilter");    }    @Override    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {        long start = System.currentTimeMillis();        HttpServletRequest httpServletRequest = (HttpServletRequest)request;        String encodeType = httpServletRequest.getHeader(CONTENT_ENCODING);        if (encodeType!=null && CONTENT_ENCODING_TYPE.equals(encodeType)) {            log.info("请求:{} 需要解压", httpServletRequest.getRequestURI());            UnZipRequestWrapper unZipRequest = new UnZipRequestWrapper(httpServletRequest);            chain.doFilter(unZipRequest, response);        }else {            log.info("请求:{} 无需解压", httpServletRequest.getRequestURI());            chain.doFilter(request,response);        }        log.info("耗时：{}ms", System.currentTimeMillis() - start);    }    @Override    public void destroy() {        log.info("destroy GzipFilter");    }}

package com.olive.config;import com.olive.filter.GzipFilter;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.web.servlet.FilterRegistrationBean;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;/** * 注册filter */@Configurationpublic class FilterRegistration {    @Autowired    private GzipFilter gzipFilter;    @Bean    public FilterRegistrationBean<GzipFilter> gzipFilterRegistrationBean() {        FilterRegistrationBean<GzipFilter> registration = new FilterRegistrationBean<>();        //Filter可以new，也可以使用依赖注入Bean        registration.setFilter(gzipFilter);        //过滤器名称        registration.setName("gzipFilter");        //拦截路径        registration.addUrlPatterns("/*");        //设置顺序        registration.setOrder(1);        return registration;    }}

该 Controller 非常简单，主要是输入请求的数据

package com.olive.controller;import java.util.HashMap;import java.util.Map;import com.alibaba.fastjson2.JSON;import com.olive.vo.ArticleRequestVO;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class TestController { @RequestMapping("/getArticle") public Map<String, Object> getArticle(@RequestBody ArticleRequestVO articleRequestVO){  Map<String, Object> result = new HashMap<>();  result.put("code", 200);  result.put("msg", "success");  System.out.println(JSON.toJSONString(articleRequestVO));  return result; }}

Controller 参数接收VO

package com.olive.vo;import lombok.Data;import java.io.Serializable;@Datapublic class ArticleRequestVO implements Serializable {    private Long id;    private String title;    private String content;}

package com.olive;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplicationpublic class Application {    public static void main(String[] args) {        SpringApplication.run(Application.class);    }}

curl -X POST \   \  -H 'content-type: application/json' \  -d '{ "id":1, "title": "java乐园", "content":"xxxxxxxxxx"}'

不要直接将压缩后的 byte[] 数组当作字符串进行传输，否则压缩后的请求数据比没压缩后的还要大得多！ 项目中一般采用以下两种传输压缩后的 byte[] 的方式：

将压缩后的 byet[] 进行 Base64 编码再传输字符串，这种方式会损失掉一部分 GZIP 的压缩效果，适用于压缩结果要存储在 Redis 中的情况将压缩后的 byte[] 以二进制的形式写入到文件中，请求时直接在 body 中带上文件即可，用这种方式可以不损失压缩效果

小编测试采用第二种方式，采用以下代码把原始数据进行压缩

public static void main(String[] args) {      ArticleRequestVO vo = new ArticleRequestVO();      vo.setId(1L);      vo.setTitle("bug弄潮儿");      try {          byte[] bytes = FileUtils.readFileToByteArray(new File("C:\\Users\\2230\\Desktop\\凯平项目资料\\改装车项目\\CXSSBOOT_DB_DDL-1.0.9.sql"));          vo.setContent(new String(bytes));          byte[] dataBytes = compress(JSON.toJSONString(vo));          saveFile("d:/vo.txt", dataBytes);      } catch (Exception e) {          e.printStackTrace();      }  }

压缩后数据存储到d:/vo.txt，然后在 postman 中安装下图选择