![[2021-11-04] 使用Java原生Http实现同时上传多个文件以及文件下载功能](http://www.mshxw.com/aiimages/31/424451.png "[2021-11-04] 使用Java原生Http实现同时上传多个文件以及文件下载功能")
首先创建两个Spring Boot项目，一个用作客户端发送Http请求，一个用作服务端接受Http请求并将文件保存至数据库中
pom.xml文件如下
服务端：
4.0.0 org.springframework.boot spring-boot-starter-parent 2.5.6 com.hk httpServer 0.0.1-SNAPSHOT httpServer httpServer 1.8 org.springframework.boot spring-boot-starter-web com.baomidou mybatis-plus-boot-starter 3.4.3.4 com.baomidou mybatis-plus-generator 3.4.1 com.baomidou mybatis-plus 3.4.3.4 org.springframework.boot spring-boot-devtools runtime true mysql mysql-connector-java org.projectlombok lombok true org.springframework.boot spring-boot-starter-test test org.springframework.boot spring-boot-starter-data-jpa org.springframework.boot spring-boot-maven-plugin org.projectlombok lombok
客户端：
4.0.0 org.springframework.boot spring-boot-starter-parent 2.5.6 com.hk httpClient 0.0.1-SNAPSHOT httpClient httpClient 1.8 org.springframework.boot spring-boot-devtools runtime true org.projectlombok lombok true org.springframework.boot spring-boot-starter-test test org.springframework.boot spring-boot-maven-plugin org.projectlombok lombok
编写客户端发送Http请求的代码，需要用到
import java.io.*; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.net.URLConnection;
上传文件方法代码：
public static String uploadFile(String actionUrl, String[] uploadFilePaths) {
String end = "rn";
String twoHyphens = "--";
String boundary = "*****";
DataOutputStream ds = null;
InputStream inputStream = null;
InputStreamReader inputStreamReader = null;
BufferedReader reader = null;
StringBuffer resultBuffer = new StringBuffer();
String tempLine = null;
try {
// 统一资源
URL url = new URL(actionUrl);
// 连接类的父类，抽象类
URLConnection urlConnection = url.openConnection();
// http的连接类
HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;
// 设置是否从httpUrlConnection读入，默认情况下是true;
httpURLConnection.setDoInput(true);
// 设置是否向httpUrlConnection输出
httpURLConnection.setDoOutput(true);
// Post 请求不能使用缓存
httpURLConnection.setUseCaches(false);
// 设定请求的方法，默认是GET
httpURLConnection.setRequestMethod("POST");
// 设置字符编码连接参数
httpURLConnection.setRequestProperty("Connection", "Keep-Alive");
// 设置字符编码
httpURLConnection.setRequestProperty("Charset", "UTF-8");
// 设置请求内容类型
httpURLConnection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
// 设置DataOutputStream
ds = new DataOutputStream(httpURLConnection.getOutputStream());
for (int i = 0; i < uploadFilePaths.length; i++) {
String uploadFile = uploadFilePaths[i];
String filename = uploadFile.substring(uploadFile.lastIndexOf("\") + 1);
ds.writeBytes(twoHyphens + boundary + end);
ds.writeBytes("Content-Disposition: form-data; " + "name="file" + i + "";filename="" + filename + """ + end);
ds.writeBytes(end);
FileInputStream fStream = new FileInputStream(uploadFile);
int bufferSize = 1024;
byte[] buffer = new byte[bufferSize];
int length = -1;
while ((length = fStream.read(buffer)) != -1) {
ds.write(buffer, 0, length);
}
ds.writeBytes(end);
fStream.close();
}
ds.writeBytes(twoHyphens + boundary + twoHyphens + end);
ds.flush();
if (httpURLConnection.getResponseCode() >= 300) {
throw new Exception("HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());
}
if (httpURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
inputStream = httpURLConnection.getInputStream();
inputStreamReader = new InputStreamReader(inputStream);
reader = new BufferedReader(inputStreamReader);
tempLine = null;
resultBuffer = new StringBuffer();
while ((tempLine = reader.readLine()) != null) {
resultBuffer.append(tempLine);
resultBuffer.append("n");
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
if (ds != null) {
try {
ds.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (inputStreamReader != null) {
try {
inputStreamReader.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (inputStream != null) {
try {
inputStream.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return resultBuffer.toString();
}
}
下载文件方法代码：
public static File downloadFile(String urlPath, String downloadDir) {
File file = null;
try {
// 统一资源
URL url = new URL(urlPath);
// 连接类的父类，抽象类
URLConnection urlConnection = url.openConnection();
// http的连接类
HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;
// 设定请求的方法，默认是GET
httpURLConnection.setRequestMethod("POST");
// 设置字符编码
httpURLConnection.setRequestProperty("Charset", "UTF-8");
// 打开到此 URL 引用的资源的通信链接（如果尚未建立这样的连接）。
httpURLConnection.connect();
// 文件大小
int fileLength = httpURLConnection.getContentLength();
// 文件名
String filePathUrl = httpURLConnection.getURL().getFile();
String fileFullName = filePathUrl.substring(filePathUrl.lastIndexOf(File.separatorChar) + 1);
System.out.println("file length---->" + fileLength);
URLConnection con = url.openConnection();
BufferedInputStream bin = new BufferedInputStream(httpURLConnection.getInputStream());
String path = downloadDir + File.separatorChar + fileFullName;
file = new File(path);
if (!file.getParentFile().exists()) {
file.getParentFile().mkdirs();
}
OutputStream out = new FileOutputStream(file);
int size = 0;
int len = 0;
byte[] buf = new byte[1024];
while ((size = bin.read(buf)) != -1) {
len += size;
out.write(buf, 0, size);
// 打印下载百分比
System.out.println("下载了-------> " + len * 100 / fileLength + "%n");
}
bin.close();
out.close();
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
return file;
}
}
编写服务端代码
Controller类，使用MultipartHttpServletRequest 接受多个文件，再使用其getFIleMap()方法获取值为MultipartFile的Map，通过Entry进行遍历获得每一个文件，代码如下：
import com.hk.httpserver.entity.File;
import com.hk.httpserver.service.FileService;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import javax.annotation.Resource;
import java.io.IOException;
import java.util.Map;
@RestController
public class FileController {
@Resource
FileService fileService;
@PostMapping("/upload")
public String upload(MultipartHttpServletRequest req) {
Map fileMap = req.getFileMap();
boolean isSuccessed = true;
try {
for(Map.Entry entry : fileMap.entrySet()) {
fileService.saveFile(entry.getValue());
}
} catch (IOException e) {
isSuccessed = false;
}
return isSuccessed ? "上传成功" : "上传失败";
}
@PostMapping("/download/{fileName}")
public byte[] download(@PathVariable("fileName") String fileName) {
File file = fileService.getFile(fileName);
return file == null ? new byte[]{} : file.getFileContent();
}
}
Service接口及实现，代码如下：
import com.hk.httpserver.entity.File;
import org.springframework.web.multipart.MultipartFile;
import java.io.IOException;
public interface FileService {
void saveFile(MultipartFile file) throws IOException;
File getFile(String fileName);
}
import com.hk.httpserver.entity.File;
import com.hk.httpserver.mapper.FileMapper;
import com.hk.httpserver.service.FileService;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;
import javax.annotation.Resource;
import java.io.IOException;
import java.util.Date;
@Service
public class FileServiceImpl implements FileService {
@Resource
FileMapper fileMapper;
@Override
public void saveFile(MultipartFile file) throws IOException {
File _file = new File();
String fileName = file.getOriginalFilename();
_file.setFileName(fileName);
_file.setFileType(file.getOriginalFilename().substring(fileName.lastIndexOf(".") + 1));
_file.setFileContent(file.getBytes());
_file.setUploadTime(new Date());
fileMapper.insert(_file);
}
@Override
public File getFile(String fileName) {
return fileMapper.selectByFileName(fileName);
}
}
使用MyBatis-Plus，Mapper代码如下：
import com.baomidou.mybatisplus.core.mapper.baseMapper; import com.hk.httpserver.entity.File; import org.apache.ibatis.annotations.Mapper; import org.apache.ibatis.annotations.Param; import org.apache.ibatis.annotations.Select; @Mapper public interface FileMapper extends baseMapper{ @Select("SELECT FILE_ID, FILE_NAME, FILE_TYPE, UPLOAD_TIME, FILE_ConTENT FROM FILE WHERe FILE_NAME = #{fileName}") File selectByFileName(@Param("fileName") String fileName); }
实体类File，代码如下：
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import com.fasterxml.jackson.annotation.JsonFormat;
import lombok.Getter;
import lombok.Setter;
import java.util.Date;
@TableName("FILE")
@Getter
@Setter
public class File {
@TableId(value = "FILE_ID", type = IdType.ASSIGN_UUID)
private String fileId;
@TableField("FILE_NAME")
private String fileName;
@TableField("FILE_TYPE")
private String fileType;
@TableField("UPLOAD_TIME")
@JsonFormat(pattern = "yyyy-MM-dd HH:mm",timezone="GMT+8")
private Date uploadTime;
@TableField("FILE_CONTENT")
private byte[] fileContent;
}
建表语句也放这里吧！
DROP TABLE IF EXISTS `file`; CREATE TABLE `file` ( `FILE_ID` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '主键', `FILE_NAME` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '文件名', `FILE_TYPE` varchar(10) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '文件类型，后缀', `UPLOAD_TIME` datetime(0) NULL DEFAULT NULL COMMENT '上传的时间', `FILE_CONTENT` mediumblob NOT NULL COMMENT '文件内容', PRIMARY KEY (`FILE_ID`) USING BTREE ) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
服务端的application.yml文件，驱动有的mysql是com.mysql.cj.jdbc.Driver，自己改一下吧
server:
port: 8890
session-timeout: 300
tomcat.max-threads: 0
tomcat.uri-encoding: UTF-8
spring:
datasource:
url: jdbc:mysql:127.0.0.1:3306/file_db?
driver-class-name: com.mysql.jdbc.Driver
username: xxxxxxxx
password: xxxxxxxx
最后，在客户端测试一下吧
import com.hk.httpclient.http.HttpHelper;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
@SpringBootTest
class HttpClientApplicationTests {
@Test
void upload() {
//测试上传
System.out.println(HttpHelper.uploadFile("http://127.0.0.1:8890/upload", new String[] { "C:\Users\Lenovo\Desktop\git.txt", "C:\Users\Lenovo\Desktop\sword_2.png"}));
//测试下载
// HttpHelper.downloadFile("http://127.0.0.1:8890/download/git.txt", "C:\Users\Lenovo\Desktop");
}
}
哇！大成功！
