• SpringBoot入门建站全系列（九）文件上传功能与下载方式
    date_range 2019-06-18 11:43:40
    folder SpringBoot专题
    person 陈付菲 公开
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    SpringBoot入门建站全系列（九）文件上传功能与下载方式

    Spring对文件上传做了简单的封装，就是用MultipartFile这个对象去接收文件，当然有很多种写法，下面会一一介绍。

    文件的下载很简单，给一个链接就行，而这个链接怎么生成，也有很多方式，下面也会讲解下常用的方式。

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    一、配置

    本文假设你已经引入spring-boot-starter-web。已经是个SpringBoot项目了,如果不会搭建，可以打开这篇文章看一看《SpringBoot入门建站全系列（一）项目建立》。因为文件上传和下载不需要引入额外的jar包了。但是需要做如下配置：

    application.properties 中需要添加下面的配置：

    spring.servlet.multipart.enabled=true
spring.servlet.multipart.max-file-size=20MB
spring.servlet.multipart.max-request-size=50MB

    这里，

    • spring.servlet.multipart.max-file-size是对单个文件大小的限制。

    • spring.servlet.multipart.max-request-size是对单次请求的大小进行限制

    至此，已经可以正常的进行上传下载了，就剩下写代码了。

    二、文件上传的几种方式

    2.1 单个文件上传

    在Controller的RequestMapping注解的方法参数中，直接将MultipartFile作为参数传递进来。

    package com.cff.springbootwork.web.file;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import com.cff.springbootwork.dto.ResultModel;
import com.cff.springbootwork.service.UploadService;

@RestController
@RequestMapping("/file")
public class FileRest {
    private Logger log = LoggerFactory.getLogger(this.getClass());

    @Value("${upload.static.url}")
    private String uploadStaticUrl;

    @Autowired
    UploadService uploadService;

    @RequestMapping("/upload")
    public ResultModel upload(@RequestParam("files") MultipartFile file) {
        try {
            if (file.isEmpty()) {
                return ResultModel.error("文件不能为空！");
            }
            String fileName = uploadService.saveUploadFile(file);
            return ResultModel.ok(uploadStaticUrl + fileName);
        } catch (Exception e) {
            e.printStackTrace();
            log.error("文件上传失败！", e);
            return ResultModel.error("文件上传失败！");
        }
    }
}

    测试的时候，使用postman可以这样传参：

    在这里插入图片描述

    2.2 多个文件上传

    在Controller的RequestMapping注解的方法参数中，直接将MultipartFile作为list传递进来。在FileRest中增加uploadList方法。

    package com.cff.springbootwork.web.file;

import java.util.ArrayList;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import com.cff.springbootwork.dto.ResultModel;
import com.cff.springbootwork.service.UploadService;

@RestController
@RequestMapping("/file")
public class FileRest {
    private Logger log = LoggerFactory.getLogger(this.getClass());

    @Value("${upload.static.url}")
    private String uploadStaticUrl;

    @Autowired
    UploadService uploadService;

    @RequestMapping("/upload")
    public ResultModel upload(@RequestParam("files") MultipartFile file) {
        try {
            if (file.isEmpty()) {
                return ResultModel.error("文件不能为空！");
            }
            String fileName = uploadService.saveUploadFile(file);
            return ResultModel.ok(uploadStaticUrl + fileName);
        } catch (Exception e) {
            e.printStackTrace();
            log.error("文件上传失败！", e);
            return ResultModel.error("文件上传失败！");
        }
    }

    @RequestMapping("/uploadList")
    public ResultModel uploadList(@RequestParam("files") List<MultipartFile> fileList) {
        try {
            List<String> list = new ArrayList<>();
            for (MultipartFile file : fileList) {
                String fileName = uploadService.saveUploadFile(file);
                list.add(uploadStaticUrl + fileName);
            }
            return ResultModel.ok(list);
        } catch (Exception e) {
            e.printStackTrace();
            log.error("文件上传失败！", e);
            return ResultModel.error("文件上传失败！");
        }
    }
}

    测试的时候，使用postman可以这样传参：

    在这里插入图片描述

    2.3 从HttpServletRequest中取文件

    新建uploadByRequest方法，将HttpServletRequest作为参数，Spring自动传入。

    Spring对Request做了一层封装，如果有文件，它就是MultipartHttpServletRequest。 然后我们可以从MultipartHttpServletRequest获取到MultipartFile。后面的处理方式一样了。

    package com.cff.springbootwork.web.file;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;

import com.cff.springbootwork.dto.ResultModel;
import com.cff.springbootwork.service.UploadService;

@RestController
@RequestMapping("/file")
public class FileRest {
    private Logger log = LoggerFactory.getLogger(this.getClass());

    @Value("${upload.static.url}")
    private String uploadStaticUrl;

    @Autowired
    UploadService uploadService;

    @RequestMapping("/upload")
    public ResultModel upload(@RequestParam("files") MultipartFile file) {
        try {
            if (file.isEmpty()) {
                return ResultModel.error("文件不能为空！");
            }
            String fileName = uploadService.saveUploadFile(file);
            return ResultModel.ok(uploadStaticUrl + fileName);
        } catch (Exception e) {
            e.printStackTrace();
            log.error("文件上传失败！", e);
            return ResultModel.error("文件上传失败！");
        }
    }

    @RequestMapping("/uploadList")
    public ResultModel uploadList(@RequestParam("files") List<MultipartFile> fileList) {
        try {
            List<String> list = new ArrayList<>();
            for (MultipartFile file : fileList) {
                String fileName = uploadService.saveUploadFile(file);
                list.add(uploadStaticUrl + fileName);
            }
            return ResultModel.ok(list);
        } catch (Exception e) {
            e.printStackTrace();
            log.error("文件上传失败！", e);
            return ResultModel.error("文件上传失败！");
        }
    }

    @RequestMapping("/uploadByRequest")
    public ResultModel uploadByRequest(HttpServletRequest request) {
        try {
            Map<String, MultipartFile> files = new HashMap<>();

            if (request instanceof MultipartHttpServletRequest) {
                MultipartHttpServletRequest req = (MultipartHttpServletRequest) request;
                MultiValueMap<String, MultipartFile> multiValueMap = req.getMultiFileMap();
                if (multiValueMap != null && !multiValueMap.isEmpty()) {
                    for (String key : multiValueMap.keySet()) {
                        files.put(key, multiValueMap.getFirst(key));
                    }
                }
            }
            if (files.isEmpty())
                return ResultModel.error("文件木有？");

            List<String> list = new ArrayList<>();
            for (MultipartFile file : files.values()) {
                String fileName = uploadService.saveUploadFile(file);
                list.add(uploadStaticUrl + fileName);
            }
            return ResultModel.ok(list);
        } catch (Exception e) {
            e.printStackTrace();
            log.error("文件上传失败！", e);
            return ResultModel.error("文件上传失败！");
        }
    }
}

    测试的时候，传参方式使用上面两种都可以了。

    三、文件下载方式

    文件上传成功后，我们同时会提供下载功能。下载功能很简单，有以下几种方式：

    3.1 Spring配置映射

    新建一个WebStaticConfig配置类，实现WebMvcConfigurer接口即可：

    import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class WebStaticConfig implements WebMvcConfigurer {
    @Value("${upload.static.local}")
    private String uploadStaticLocal;

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("file:" + uploadStaticLocal);
    }

    public String getUploadStaticLocal() {
        return uploadStaticLocal;
    }

    public void setUploadStaticLocal(String uploadStaticLocal) {
        this.uploadStaticLocal = uploadStaticLocal;
    }

}

    这句话将当前服务器（比如是http://127.0.0.1:8080 ）的/static路径（http://127.0.0.1:8080/static/ ）下的资源，映射到uploadStaticLocal指定的本地路径下的文件。

    然后我们就可以直接访问文件了。

    3.2 代理(nginx)映射

    代理首选nginx了。高性能快捷的代理转发工具。

    比如要将http://127.0.0.1:8081/static/ 下的资源，映射到/static/指定的本地路径下的文件，可以这样配置：

    server {
    listen       8081;
    server_name  localhost;

    location /static {
        alias /static/;
        index index.html;
    }
}

    这里为什么用8081而不是上面的8080了呢？因为上面的8080端口已经被SpringBoot应用占用了。nginx要在另一个端口监听了，如果非要将SpringBoot应用和静态资源在一个端口，可以对SpringBoot应用也做代理，例如：

    server {
    listen       8081;
    server_name  localhost;

    location ^~ /api/ {
        proxy_pass   http://127.0.0.1:8080/;
    }

    location /static {
        alias /static/;
        index index.html;
    }
}

    3.3 ResponseEntity读取文件并返回

    比如我们在FileRest的Controller中建立个downloadFile方法，传入文件名，将文件读取为byte，包装成ResponseEntity返回。

        @RequestMapping(value = "/downloadFile", method = { RequestMethod.GET })
    public ResponseEntity<byte[]> downloadFile(@RequestParam("fileName") String fileName) {
        try {
            File file = new File(fileName);
            byte[] body = null;
            InputStream is = new FileInputStream(file);
            body = new byte[is.available()];
            is.read(body);
            is.close();
            HttpHeaders headers = new HttpHeaders();
            headers.add("Content-Disposition", "attchement;filename=" + file.getName());
            HttpStatus statusCode = HttpStatus.OK;
            ResponseEntity<byte[]> entity = new ResponseEntity<byte[]>(body, headers, statusCode);
            return entity;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }

    }

    四、过程中用到的实体及Service

    UploadService：

    package com.cff.springbootwork.service;

import java.io.File;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;

@Service
public class UploadService {
    @Value("${upload.static.local}")
    private String uploadStaticLocal;

    public String saveUploadFile(MultipartFile file) throws Exception {
        String fileName = file.getOriginalFilename();

        String localPath = uploadStaticLocal + fileName;
        file.transferTo(new File(localPath));

        return fileName;
    }

}

    ResultCode：

    package com.cff.springbootwork.dto;

/**
 * 响应码及其描述 Created by txl on 15/7/9.
 */
public enum ResultCode {

    /**
     * 通用
     */
    CODE_00000("00000", "操作成功"), CODE_00001("00001", "请求失败"), CODE_00002("00002", "错误的请求方法"), CODE_00003("00003", "非法的参数字段"), CODE_00004("00004", "异常抛出"), CODE_00005("00005", "权限不足"), CODE_00006("00006", "分页limit参数错误"), CODE_00007("00007", "分页offset参数错误"), CODE_00009("00009", "请求过于频繁"), CODE_00010("00010", "数据已存在"), CODE_00011("00011", "数据不存在"), CODE_00012("00012", "参数缺失"), CODE_00013("00013", "系统维护中"), CODE_00014("00014", "token缺失"), CODE_00015("00015", "token失效"), CODE_00016("00016", "签名错误"),

    CODE_10000("10000", "操作部分成功"),
    /**
     * 系统
     */
    CODE_30000("30000", "系统ID错误"),

    /**
     * 授权
     */
    CODE_40001("40001", "用户未找到"), CODE_40002("40002", "该用户状态异常"), CODE_40003("40003", "该用户已被删除"), CODE_40004("40004", "授权异常"),

    CODE_99999("99999", "签名无效");

    private String code;
    private String desc;

    ResultCode(String code, String desc) {
        this.code = code;
        this.desc = desc;
    }

    public String getCode() {
        return code;
    }

    public String getDesc() {
        return desc;
    }

    /**
     * 根据code匹配枚举
     * 
     * @param code
     * @return
     */
    public static ResultCode getResultCodeByCode(String code) {
        for (ResultCode resultCode : ResultCode.values()) {
            if (code.equals(resultCode.getCode())) {
                return resultCode;
            }
        }
        return null;
    }

    public static ResultCode getResultCodeByDesc(String desc) {
        for (ResultCode resultCode : ResultCode.values()) {
            if (desc.equals(resultCode.getDesc())) {
                return resultCode;
            }
        }
        return null;
    }
}

    ResultModel ：

    package com.cff.springbootwork.dto;

/**
 */
public class ResultModel {

    private String errorCode;
    private String message;
    private Object remark;
    private Object data;

    public ResultModel(String errorCode, String message) {
        this.errorCode = errorCode;
        this.message = message;
    }

    public ResultModel() {
    }

    public ResultModel(String errorCode, String message, Object data) {
        this.errorCode = errorCode;
        this.message = message;
        this.data = data;
    }

    public ResultModel(ResultCode resultCodeEnum, Object data) {
        this.errorCode = resultCodeEnum.getCode();
        this.message = resultCodeEnum.getDesc();
        this.data = data;
    }

    public ResultModel(ResultCode resultCodeEnum, Object data, Object remark) {
        this.errorCode = resultCodeEnum.getCode();
        this.message = resultCodeEnum.getDesc();
        this.data = data;
        this.remark = remark;
    }

    public ResultModel(ResultCode resultCodeEnum) {
        this.errorCode = resultCodeEnum.getCode();
        this.message = resultCodeEnum.getDesc();
    }

    public String getErrorCode() {
        return errorCode;
    }

    public void setErrorCode(String errorCode) {
        this.errorCode = errorCode;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public Object getData() {
        return data;
    }

    public void setData(Object data) {
        this.data = data;
    }

    public static ResultModel ok() {
        return new ResultModel(ResultCode.CODE_00000);
    }

    public static ResultModel ok(Object data) {
        return new ResultModel(ResultCode.CODE_00000, data);
    }

    public static ResultModel unAuth() {
        return new ResultModel(ResultCode.CODE_00002);
    }

    public static ResultModel unAuth(Object data) {
        return new ResultModel(ResultCode.CODE_00002, data);
    }

    public static ResultModel error(String message) {
        return new ResultModel(ResultCode.CODE_00001.getCode(), message);
    }

    public Object getRemark() {
        return remark;
    }

    public void setRemark(Object remark) {
        this.remark = remark;
    }

}
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  • tiantian : 文件下载那里，，感觉说的有些模糊，不是很明白 5年前 回复 隐藏回复
    • feiyang 回复 tiantian : 下载一般用nginx做静态资源的代理转发，springboot做转发是用addResourceHandler将某个url映射到本地路径而已。 5年前 回复
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