restful api上傳文件（基礎）-springboot

基於restful api格式的文件上傳（只是上傳到本地）：

package com.nxz.controller;

import com.nxz.entity.FileInfo;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.IOException;
import java.util.Date;

@RestController
@RequestMapping("/file")
public class FileController {
    @PostMapping
    public FileInfo update(MultipartFile file) throws IOException {

        System.out.println(file.getName());
        System.out.println(file.getOriginalFilename());
        System.out.println(file.getSize());

        String holder = "G:\\0001-myproject\\mysecurity\\mysecurity-demo\\src\\main\\java\\com\\nxz\\controller";

        File localFile = new File(holder, new Date().getTime() + ".txt");

        file.transferTo(localFile);


        return new FileInfo(localFile.getAbsolutePath());
    }

}

 

測試用例：

   //偽造的mvc環境
    @Autowired
    private WebApplicationContext webApplicationContext;
    private MockMvc mockMvc;
    @Before
    public void before() {
        mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext).build();
    }
    @Test
    public void whenUploadSuccess() throws Exception {
        String file = mockMvc.perform(MockMvcRequestBuilders.fileUpload("/file")
                .file(new MockMultipartFile("file", "test.txt", "multipart/form-data", "hello".getBytes("UTF-8"))))
                .andExpect(MockMvcResultMatchers.status().isOk())
                .andReturn().getResponse().getContentAsString();
        System.out.println(file);
    }

測試用例執行完之后輸出文件絕對路徑：

{"path":"G:\\mysecurity\\mysecurity-demo\\src\\main\\java\\com\\nxz\\controller\\1556463660034.txt"}

 

 

下載：

 @GetMapping("/{id}")
    public void downLoad(@PathVariable String id,
                         HttpServletRequest request,
                         HttpServletResponse response) throws IOException {
        String holder = "G:\\0001-myproject\\mysecurity\\mysecurity-demo\\src\\main\\java\\com\\nxz\\controller";
        try (
                InputStream inputStream = new FileInputStream(new File(holder, id + ".txt"));
                OutputStream outputStream = response.getOutputStream();
        ) {
            response.setContentType("application/x-download");
            response.addHeader("Content-Disposition", "attachment;filename=test.txt");//重新定義下載后名稱
            //將文件輸入流復制到輸出劉超過年 commons-io依賴
            IOUtils.copy(inputStream, outputStream);
            outputStream.flush();
        }

    }

訪問：http://localhost:8080/user/1

 

 

springboot中上傳文件：

java中和文件上傳的類又兩個：CommonsMultipartResolver，另一個就是StandardServletMultipartResolver，其中commonsMultipartResolver需要commons-fileupload支持，二StandardServletMultipartReslover是servlet3.0默認支持的，tomcat7以上版本就開始支持servlet7.0，springboot22.0之后支持的tomcat版本在7之后，因此是支持StandardServletMultipartReslover的

首先 springboot只要配置好pom（有spring-boot-starter-web依賴），就能自動支持文件上傳（包括單文件和多文件），那么springboot中文件上傳是怎樣起作用的

1、pom依賴，下邊這些依賴中，和配置文件上傳有關的就是spring-boot-autoconfig依賴

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

---->>>

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter</artifactId>
      <version>2.1.3.RELEASE</version>
      <scope>compile</scope>
    </dependency>



---->>>>
    
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-autoconfigure</artifactId>
      <version>2.1.3.RELEASE</version>
      <scope>compile</scope>
    </dependency>

 

2、那么看下spring-boot-autoconfig jar包中的spring.factories文件中的內容，這個文件中全都是和springboot自動配置相關的類的全文件名，其中和文件上傳有關的是

org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration,\

3、進入這個類中（具體個各種autoconfiguration自動加載類是什么時候加載的，需要看springboot的啟動來注解和啟動類）

@Configuration
@ConditionalOnClass({ Servlet.class, StandardServletMultipartResolver.class, MultipartConfigElement.class }) //這個注解表示存在servlet、StandardServletMultipartResolver、multipartConfigElement文件時才加載該類 @ConditionalOnProperty(prefix = "spring.servlet.multipart", name = "enabled", matchIfMissing = true)//配置文件的前綴 @ConditionalOnWebApplication(type = Type.SERVLET)//servlet @EnableConfigurationProperties(MultipartProperties.class)//配置文件類 public class MultipartAutoConfiguration { private final MultipartProperties multipartProperties; public MultipartAutoConfiguration(MultipartProperties multipartProperties) { this.multipartProperties = multipartProperties; } @Bean @ConditionalOnMissingBean({ MultipartConfigElement.class, CommonsMultipartResolver.class })//當沒有commonsMultipartResolver文件時，初始化該bean public MultipartConfigElement multipartConfigElement() { return this.multipartProperties.createMultipartConfig(); } @Bean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME) @ConditionalOnMissingBean(MultipartResolver.class) public StandardServletMultipartResolver multipartResolver() { StandardServletMultipartResolver multipartResolver = new StandardServletMultipartResolver();//springboot默認的文件上傳的類 multipartResolver.setResolveLazily(this.multipartProperties.isResolveLazily()); return multipartResolver; } }