springboot(45) : 浏览器预览文件

参考 :?

????????Servlet之文件预览_httpservletresponse 设置文件预览-CSDN博客?

????????java如何获取文件的媒体类型（MIME类型）？ - Java中文网?

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.activation.MimetypesFileTypeMap;
import javax.servlet.http.HttpServletResponse;
import java.io.*;

@Controller
public class YuLangController {

    @RequestMapping("/yl/{fileName}")
    public void yl(@PathVariable("fileName") String fileName, HttpServletResponse response) throws Exception {
        MimetypesFileTypeMap mimeTypesMap = new MimetypesFileTypeMap();
        String mimeType = mimeTypesMap.getContentType(fileName);
        // 获取文件的媒体类型
        response.setContentType(mimeType);
        // 输出文件 fileName为相对路径 fileName= [System.getProperty("user.dir")+File.separator+fileName]
        InputStream is = new FileInputStream(fileName);
        OutputStream os = response.getOutputStream();
        BufferedOutputStream bos = new BufferedOutputStream(os);
        byte[] buffer = new byte[1024];
        int len = -1;
        while ((len = is.read(buffer)) != -1) {
            bos.write(buffer, 0, len);
        }
        // 关闭流
        bos.flush();
        bos.close();
        is.close();
    }
}