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📜  Spring Boot-文件处理

📅  最后修改于: 2020-11-11 05:37:41             🧑  作者: Mango

在本章中，您将学习如何使用Web服务上载和下载文件。

上传文件

要上传文件，您可以将MultipartFile用作请求参数，并且此API应该使用Multi-Part表单数据值。遵守下面给出的代码-

@RequestMapping(value = "/upload", method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE)

public String fileUpload(@RequestParam("file") MultipartFile file) {
   return null;
}

相同的完整代码如下-

package com.tutorialspoint.demo.controller;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

@RestController
public class FileUploadController {
   @RequestMapping(value = "/upload", method = RequestMethod.POST, 
      consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
   
   public String fileUpload(@RequestParam("file") MultipartFile file) throws IOException {
      File convertFile = new File("/var/tmp/"+file.getOriginalFilename());
      convertFile.createNewFile();
      FileOutputStream fout = new FileOutputStream(convertFile);
      fout.write(file.getBytes());
      fout.close();
      return "File is upload successfully";
   }
}

档案下载

对于文件下载，应使用InputStreamResource下载文件。我们需要在Response中设置HttpHeader Content-Disposition ，并需要指定应用程序的响应媒体类型。

注–在以下示例中，文件应在应用程序运行所在的指定路径上可用。

@RequestMapping(value = "/download", method = RequestMethod.GET) 
public ResponseEntity downloadFile() throws IOException  {
   String filename = "/var/tmp/mysql.png";
   File file = new File(filename);
   InputStreamResource resource = new InputStreamResource(new FileInputStream(file));
   HttpHeaders headers = new HttpHeaders();
      
   headers.add("Content-Disposition", String.format("attachment; filename=\"%s\"", file.getName()));
   headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
   headers.add("Pragma", "no-cache");
   headers.add("Expires", "0");
      
   ResponseEntity 
   responseEntity = ResponseEntity.ok().headers(headers).contentLength(file.length()).contentType(
      MediaType.parseMediaType("application/txt")).body(resource);
      
   return responseEntity;
}

相同的完整代码如下-

package com.tutorialspoint.demo.controller;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

import org.springframework.core.io.InputStreamResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class FileDownloadController {
   @RequestMapping(value = "/download", method = RequestMethod.GET) 
   public ResponseEntity downloadFile() throws IOException  {
      String filename = "/var/tmp/mysql.png";
      File file = new File(filename);
      InputStreamResource resource = new InputStreamResource(new FileInputStream(file));
      HttpHeaders headers = new HttpHeaders();
      
      headers.add("Content-Disposition", String.format("attachment; filename=\"%s\"", file.getName()));
      headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
      headers.add("Pragma", "no-cache");
      headers.add("Expires", "0");
      
      ResponseEntity 
      responseEntity = ResponseEntity.ok().headers(headers).contentLength(
         file.length()).contentType(MediaType.parseMediaType("application/txt")).body(resource);
      
      return responseEntity;
   }
}

下面给出了主要的Spring Boot应用程序-

package com.tutorialspoint.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {
   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
}

下面给出了Maven构建的代码– pom.xml-


 
   
   4.0.0
   com.tutorialspoint
   demo
   0.0.1-SNAPSHOT
   jar
   demo
   Demo project for Spring Boot

   
      org.springframework.boot
      spring-boot-starter-parent
      1.5.8.RELEASE
       
   

   
      UTF-8
      UTF-8
      1.8
   

   
      
         org.springframework.boot
         spring-boot-starter-web
      

      
         org.springframework.boot
         spring-boot-starter-test
         test
      
   

   
      
         
            org.springframework.boot
            spring-boot-maven-plugin

下面给出了Gradle Build – build.gradle的代码-

buildscript {
   ext {
      springBootVersion = '1.5.8.RELEASE'
   }
   repositories {
      mavenCentral()
   }
   dependencies {
      classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
   }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'

group = 'com.tutorialspoint'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8

repositories {
   mavenCentral()
}
dependencies {
   compile('org.springframework.boot:spring-boot-starter-web')
   testCompile('org.springframework.boot:spring-boot-starter-test')
}

现在您可以创建一个可执行的JAR文件，并使用下面给出的Maven或Gradle命令运行Spring Boot应用程序-

对于Maven，请使用下面给出的命令-

mvn clean install

在“ BUILD SUCCESS”之后，您可以在目标目录下找到JAR文件。

对于Gradle，您可以使用下面显示的命令-

sgradle clean build

在“ BUILD SUCCESSFUL”之后，您可以在build / libs目录下找到JAR文件。

现在，使用以下命令运行JAR文件：

java –jar

这将在Tomcat端口8080上启动应用程序，如下所示-

邮递员申请

现在在POSTMAN应用程序中点击以下URL，您可以看到如下所示的输出-

文件上传-http：// localhost：8080 / upload

POSTMAN应用程序文件上传

文件下载-http：// localhost：8080 / upload