SpringMVC 实现文件上传/下载

文章目录

• ​​1. 上传文件​​

• ​​1.1 单文件上传​​
• ​​1.2 单文件html代码​​
• ​​1.3 多文件上传​​
• ​​1.4 多文件html代码​​
• ​​文件上传带参数​​

• ​​2. 下载文件​​
• ​​3. 文件转文件16进制字符串​​
• ​​4. 文件16进制字符串转文件​​
• ​​5. 文件16进制字符串转文件输入流​​
• ​​6. 工具类方法​​
• ​​7. 上传文件大小限制配置​​
• ​​报错​​

• ​​文件过大问题​​
• ​​解决方案​​

1. 上传文件

1.1 单文件上传

@RequestMapping(value = "upload", method = RequestMethod.POST)
@ResponseBody
public String upload(MultipartFile excel) throws IOException {
    // ...  
    return "success";
}

注意接口 upload 的参数名称是excel， 在 调用时文件的 key 也得是 excel

 

 

1.2 单文件html代码

<form action="XXXXXX" enctype="multipart/form-data" method="post">
    <input type="file" name="excel" />
        <br/>
    <input type="submit" value="上传文件" />
</form>

 

1.3 多文件上传

@RequestMapping(value = "multiUpload", method = RequestMethod.POST)
@ResponseBody
public String multiUpload(@RequestParam("file") MultipartFile[] files) {
    String[] fileNames = new String[files.length];
    for (int i = 0; i < files.length; i++) {
        MultipartFile file = files[i];
        if (!file.isEmpty()) {
            fileNames[i] = file.getOriginalFilename();
        }
    }
    // ...
    return Arrays.asList(fileNames).toString();
}

 

 

1.4 多文件html代码

<form action="XXXXXX" enctype="multipart/form-data" method="post">
    文件1: <input type="file" name="file" />
    <br/>
    文件2: <input type="file" name="file" />
    <br/>
    <input type="submit" value="上传所有文件" />
</form>

 

文件上传带参数

@RequestMapping("/upload")
public Response upload(@RequestParam MultipartFile file, 
    @RequestParam("id") String id, @RequestParam String userName) {
    // ...
    return Response.success(id + "=" + userName);
}

 

2. 下载文件

@RequestMapping(value = "{fileName}")
public void download(@PathVariable("fileName") String fileName, HttpServletResponse response) {
    // 根据 fileName 找到下载文件所在路径
    String filePath = "/home/answer/" + fileName;
    try {
        File file = new File(filePath);
        String filename = file.getName();

        InputStream is = new BufferedInputStream(new FileInputStream(filePath));
        byte[] buffer = new byte[is.available()];
        is.read(buffer);
        is.close();

        response.reset();
        response.setCharacterEncoding(Charsets.UTF_8.name());
        response.addHeader("Content-Disposition", String.format("%s%s", "attachment;filename=", filename));
        response.addHeader("Content-Length", String.valueOf(file.length()));
        OutputStream os = new BufferedOutputStream(response.getOutputStream());
        // application/octet-stream 不知道下载文件类型 application/x-xls
        response.setContentType("application/vnd.ms-excel");
        os.write(buffer);
        os.flush();
        os.close();
    } catch (IOException ex) {
        ex.printStackTrace();
    }
}

 

3. 文件转文件16进制字符串

public class AIApp {
    public static void main(String[] args) throws IOException {
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream("C:\\Users\\answer\\work_detail.txt"));
        byte[] bytes = new byte[bis.available()];
        bis.read(bytes, 0, bis.available());

        System.out.println(bytesToHexString(bytes));
    }
}

 

4. 文件16进制字符串转文件

public class AIApp {
    public static void main(String[] args) throws IOException {
        String fileHexString = "";
        byte[] bytes = hexStringToBytes(fileHexString);

        if (bytes != null) {
            File file = new File("C:\\Users\\answer\\work.txt");
            BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));
            bos.write(bytes);
            bos.flush();
            bos.close();
        }
    }
}

 

5. 文件16进制字符串转文件输入流

/**
 * 文件16进制字符串转文件流
 *
 * @param hexString 十六进制字符串
 * */
public static InputStream hexToInputStream(String hexString) {
    byte[] bytes = hexStringToBytes(hexString);
    Assert.notNull(bytes, "bytes is null.");
    return new ByteArrayInputStream(bytes);
}

 

6. 工具类方法

/**
 * 十六进制字符串转字节数组
 *
 * @param  hexString 十六进制字符串
 * */
public static byte[] hexStringToBytes(String hexString) {
    if (StringUtils.isEmpty(hexString)) {
        return null;
    }
    hexString = hexString.toUpperCase();
    int length = hexString.length() / 2;
    char[] hexChars = hexString.toCharArray();
    byte[] d = new byte[length];
    for (int i = 0; i < length; i++) {
        int pos = i * 2;
        d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
    }
    return d;
}

/**
 * 字符转字节
 * */
public static byte charToByte(char c) {
    return (byte) "0123456789ABCDEF".indexOf(c);
}

/**
 * 字节数组转16进制字符串
 *
 * @param bytes 字节数组
 * */
public static String bytesToHexString(byte[] bytes){
    StringBuilder stringBuilder = new StringBuilder("");
    if (bytes == null || bytes.length <= 0) {
        return "";
    }

    for (byte b: bytes) {
        int v = b & 0xFF;
        String hv = Integer.toHexString(v);
        if (hv.length() < 2) {
            stringBuilder.append(0);
        }
        stringBuilder.append(hv);
    }
    return stringBuilder.toString().toUpperCase();
}

 

7. 上传文件大小限制配置

# 配置文件传输
# spring.servlet.multipart.enabled =true  
# spring.servlet.multipart.file-size-threshold =0
# 单个数据的大小
spring.servlet.multipart.max-file-size=1024MB
# 总数据的大小
spring.servlet.multipart.max-request-size=1024MB

 

报错

文件过大问题

Maximum upload size exceeded; nested exception is java.lang.IllegalStateException: org.apache.tomcat.util.http.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (14809675) exceeds the configured maximum (10485760)

解决方案

解决方案1

# 解决方案： application.properties add
spring:
  servlet:
    multipart:
      max-file-size: 1024MB
      max-request-size: 1024MB
      location: /home/jaemon/temp

解决方案2

@Configuration
public class MultipartConfig {
    @Bean
    public MultipartConfigElement multipartConfigElement() {
        MultipartConfigFactory factory = new MultipartConfigFactory();
        factory.setMaxFileSize("1024MB");
        factory.setMaxRequestSize("1024MB");
        // 上传文件临时目录
        factory.setLocation("/home/jaemon/temp");
        return factory.createMultipartConfig();
    }
}