Spring Mvc下实现以文件流方式下载文件的方法示例

下面是针对“Spring MVC下实现以文件流方式下载文件的方法示例”的完整攻略：

1. 需求分析

我们需要实现一个以文件流方式下载文件的功能，具体来说，就是用户在调用该接口时，能够将指定文件以文件流的形式返回浏览器端，让用户下载文件。

2. 实现步骤

2.1 定义接口

我们需要在Controller中定义一个接口来实现文件下载的功能，具体的代码如下：

@RequestMapping(value = "/downloadFile", method = RequestMethod.GET)
public void downloadFile(HttpServletResponse response) throws IOException {
    // 下载文件代码
}

2.2 获取文件

接下来，我们需要获取指定的文件。这里我们使用了FileInputStream来读取文件。

File file = new File("文件路径");
InputStream inputStream = new FileInputStream(file);

2.3 设置返回头

将文件返回给浏览器前，需要先设置响应头，告诉浏览器下载文件的类型、大小和名称等，具体代码如下：

response.setHeader("Content-Disposition", "attachment;filename=" + file.getName());
response.addHeader("Content-Length", "" + file.length());
response.setContentType("application/octet-stream;charset=UTF-8");

2.4 输出文件流

最后，我们将文件内容通过response的输出流返回给浏览器，代码如下：

OutputStream outputStream = response.getOutputStream();
byte[] buffer = new byte[1024];
int len;
while ((len = inputStream.read(buffer)) > 0) {
  　　　　　outputStream.write(buffer, 0, len);
}
outputStream.flush();
inputStream.close();

完整的Controller代码如下：

@RequestMapping(value = "/downloadFile", method = RequestMethod.GET)
public void downloadFile(HttpServletResponse response) throws IOException {
    File file = new File("文件路径");
    InputStream inputStream = new FileInputStream(file);
    response.setHeader("Content-Disposition", "attachment;filename=" + file.getName());
    response.addHeader("Content-Length", "" + file.length());
    response.setContentType("application/octet-stream;charset=UTF-8");
    OutputStream outputStream = response.getOutputStream();
    byte[] buffer = new byte[1024];
    int len;
    while ((len = inputStream.read(buffer)) > 0) {
        outputStream.write(buffer, 0, len);
    }
    outputStream.flush();
    inputStream.close();
}

3. 示例说明

示例一

我们在项目中需要提供一个下载PDF文档的功能，用户可以通过访问"/downloadPDF"接口来下载指定的PDF文件。

@RequestMapping(value = "/downloadPDF", method = RequestMethod.GET)
public void downloadPdf(HttpServletResponse response) throws IOException {
    File pdf = new File("pdf文件路径");
    InputStream inputStream = new FileInputStream(pdf);
    response.setHeader("Content-Disposition", "attachment;filename=" + pdf.getName());
    response.addHeader("Content-Length", "" + pdf.length());
    response.setContentType("application/octet-stream;charset=UTF-8");
    OutputStream outputStream = response.getOutputStream();
    byte[] buffer = new byte[1024];
    int len;
    while ((len = inputStream.read(buffer)) > 0) {
        outputStream.write(buffer, 0, len);
    }
    outputStream.flush();
    inputStream.close();
}

示例二

我们在项目中需要提供一个下载Word文档的功能，用户可以通过访问"/downloadWord"接口来下载指定的Word文件。

@RequestMapping(value = "/downloadWord", method = RequestMethod.GET)
public void downloadWord(HttpServletResponse response) throws IOException {
    File word = new File("Word文件路径");
    InputStream inputStream = new FileInputStream(word);
    response.setHeader("Content-Disposition", "attachment;filename=" + word.getName());
    response.addHeader("Content-Length", "" + word.length());
    response.setContentType("application/octet-stream;charset=UTF-8");
    OutputStream outputStream = response.getOutputStream();
    byte[] buffer = new byte[1024];
    int len;
    while ((len = inputStream.read(buffer)) > 0) {
        outputStream.write(buffer, 0, len);
    }
    outputStream.flush();
    inputStream.close();
}

以上就是关于“Spring Mvc下实现以文件流方式下载文件的方法示例”的完整攻略。