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0. 开发环境

IDE：IntelliJ IDEA 2017.1 x64
jdk：1.8.0_91
Spring Boot：2.1.1.RELEASE

1. 文件下载

1.1 新建服务类

import cn.wbnull.springbootdemo.boot.GlobalException;import org.springframework.stereotype.Service;import javax.servlet.http.HttpServletResponse;import java.io.BufferedInputStream;import java.io.File;import java.io.FileInputStream;import java.io.OutputStream;@Servicepublic class LogService {  public void logDownload(String name, HttpServletResponse response) throws Exception {    File file = new File("logs" + File.separator + name);    if (!file.exists()) {      throw new GlobalException(name + "文件不存在");     }    response.setContentType("application/force-download");    response.addHeader("Content-Disposition", "attachment;fileName=" + name);    byte[] buffer = new byte[1024];    FileInputStream fis = null;    BufferedInputStream bis = null;    try {      fis = new FileInputStream(file);      bis = new BufferedInputStream(fis);      OutputStream os = response.getOutputStream();      int i = bis.read(buffer);      while (i != -1) {        os.write(buffer, 0, i);        i = bis.read(buffer);       }     } finally {      if (bis != null) {        bis.close();       }      if (fis != null) {        fis.close();       }     }   }}

1.2 新建控制器类

import cn.wbnull.springbootdemo.service.LogService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.annotation.Scope;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import javax.servlet.http.HttpServletResponse;@RestController@Scope("prototype")@RequestMapping("/log")public class LogController {  @Autowired  private LogService logService;  /**   * 下载日志接口   *   * @param name   * @param response   * @throws Exception   */  @GetMapping(value = "/download/{name}")  public void logDownload(@PathVariable String name, HttpServletResponse response) throws Exception {    logService.logDownload(name, response);   }}

1.3 测试

上面接口是要下载logs文件夹下日志文件，以log_20190218.log日志文件为例，浏览器直接访问 http://127.0.0.1:8090/springbootdemo/log/download/log_20190218.log 即可完成下载。

2. 单文件上传

2.1 新建服务类

import cn.wbnull.springbootdemo.boot.GlobalException;import cn.wbnull.springbootdemo.model.ReturnMessage;import com.alibaba.fastjson.JSONObject;import org.springframework.stereotype.Service;import org.springframework.web.multipart.MultipartFile;import javax.servlet.http.HttpServletResponse;import java.io.*;@Servicepublic class LogService {  public JSONObject logUpload(MultipartFile file) throws Exception {    if (file == null || file.isEmpty()) {      throw new GlobalException("未选择需上传的日志文件");     }    String filePath = new File("logs_app").getAbsolutePath();    File fileUpload = new File(filePath);    if (!fileUpload.exists()) {      fileUpload.mkdirs();     }    fileUpload = new File(filePath, file.getOriginalFilename());    if (fileUpload.exists()) {      throw new GlobalException("上传的日志文件已存在");     }    try {      file.transferTo(fileUpload);      return ReturnMessage.success();     } catch (IOException e) {      throw new GlobalException("上传日志文件到服务器失败：" + e.toString());     }   }}

2.2 新建控制器类

import cn.wbnull.springbootdemo.service.LogService;import com.alibaba.fastjson.JSONObject;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.annotation.Scope;import org.springframework.web.bind.annotation.*;import org.springframework.web.multipart.MultipartFile;import javax.servlet.http.HttpServletResponse;@RestController@Scope("prototype")@RequestMapping("/log")public class LogController {  @Autowired  private LogService logService;  /**   * 上传日志接口   *   * @param file   * @return   * @throws Exception   */  @PostMapping(value = "/upload")  public JSONObject logUpload(@RequestParam("file") MultipartFile file) throws Exception {    return logService.logUpload(file);   }}

2.3 新建HTML页面

log-upload.html

<!DOCTYPE html><html lang="en"><head>  <meta charset="UTF-8">  <title>文件上传</title></head><body><form method="post" action="/log/upload" enctype="multipart/form-data">  <input type="file" name="file">  <br><br>  <input type="submit" value="提交"></form></body></html>

2.4 测试

浏览器打开页面 http://127.0.0.1:8090/springbootdemo/log-upload.html

点击选择文件打开文件选择页面，选中需要上传的文件后，点击提交，返回如下则为文件上传成功。

我们去logs_app文件夹下查看，生成了上传的日志文件。

2.5 Java客户端上传文件

上面我们上传文件的客户端为HTML页面，但我们实际生产中未必是WebAPP，这时我们可以通过模拟发送浏览器HTTP请求来实现上传文件。

2.5.1 引入依赖

    <dependency>      <groupId>commons-httpclient</groupId>      <artifactId>commons-httpclient</artifactId>      <version>3.1</version>    </dependency>

2.5.2 新建Java客户端

import org.apache.commons.httpclient.HttpClient;import org.apache.commons.httpclient.methods.PostMethod;import org.apache.commons.httpclient.methods.multipart.FilePart;import org.apache.commons.httpclient.methods.multipart.MultipartRequestEntity;import org.apache.commons.httpclient.methods.multipart.Part;import org.apache.commons.httpclient.params.HttpMethodParams;import org.junit.Test;import java.io.File;import java.io.IOException;public class LogControllerTests {  @Test  public void logUpload() throws Exception {    String url = "http://127.0.0.1:8090/springbootdemo/log/upload";    String pathname = new File("logs" + File.separator + "log_20190310.log").getCanonicalPath();    logUpload(url, pathname);   }  private static void logUpload(String url, String pathname) {    HttpClient httpClient = new HttpClient();    PostMethod postMethod = new PostMethod(url);    try {      FilePart filePart = new FilePart("file", new File(pathname));      Part[] parts = {filePart};      MultipartRequestEntity multipartRequestEntity = new MultipartRequestEntity(parts, new HttpMethodParams());      postMethod.setRequestEntity(multipartRequestEntity);      httpClient.executeMethod(postMethod);      String result = postMethod.getResponseBodyAsString();      System.out.println(result);     } catch (IOException e) {      e.printStackTrace();     } finally {      postMethod.releaseConnection();     }   }}

这里，以下两行代码表示设置多媒体参数，作用类似form表单中的enctype="multipart/form-data"

MultipartRequestEntity multipartRequestEntity = new MultipartRequestEntity(parts, new HttpMethodParams());postMethod.setRequestEntity(multipartRequestEntity);

以下两行代码表示设定参数名称和值，类似form表单中的<input name="file” type="file" />

FilePart filePart = new FilePart("file", new File(pathname));Part[] parts = {filePart};

2.5.3 测试

测试类运行成功。

文件上传成功

3. 多文件上传

3.1 新建服务类

  public JSONObject logUploads(HttpServletRequest request) throws Exception {    List<MultipartFile> files = ((MultipartHttpServletRequest) request).getFiles("file");    for (MultipartFile file : files) {      logUpload(file);     }    return ReturnMessage.success();   }

3.2 新建控制器类

  /**   * 批量上传日志接口   *   * @param request   * @return   * @throws Exception   */  @PostMapping(value = "/uploads")  public JSONObject logUploads(HttpServletRequest request) throws Exception {    return logService.logUploads(request);   }

3.3 新建HTML页面

log-uploads.html

<!DOCTYPE html><html lang="en"><head>  <meta charset="UTF-8">  <title>批量文件上传</title></head><body><form method="post" action="log/uploads" enctype="multipart/form-data">  <input type="file" name="file"><br>  <input type="file" name="file"><br>  <input type="file" name="file"><br>  <br>  <input type="submit" value="提交"></form></body></html>

3.4 测试

我们先把之前测试上传的logs_app文件夹整个删除，然后浏览器打开页面 http://127.0.0.1:8090/springbootdemo/log-uploads.html

选择要上传的文件

点击提交，返回如下则为上传成功。

我们去logs_app文件夹下查看，生成了上传的日志文件。

3.5 Java客户端上传文件

这里如果我们也需要Java客户端实现多文件上传，可以仿照2.5实现。

GitHub：https://github.com/dkbnull/SpringBootDemo

CSDN：https://blog.csdn.net/dkbnull/article/details/88858717

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