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springboot：各种下载文件的方式(springboot常用)
编辑：rootadminspringboot：各种下载文件的方式 文章目录springboot：各种下载文件的方式一、使用response输出流下载二、使用ResponseEntity三、注意springboot：各种下载文件的方式一、使用response输出流下载
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注意第一种方式返回值必须为void
@GetMapping("/t1") public void down1(HttpServletResponse response) throws Exception { response.reset(); response.setContentType("application/octet-stream;charset=utf-8"); response.setHeader( "Content-disposition", "attachment; filename=test.png"); try( BufferedInputStream bis = new BufferedInputStream(new FileInputStream("E:\\desktop\\1.png")); // 输出流 BufferedOutputStream bos = new BufferedOutputStream(response.getOutputStream()); ){ byte[] buff = new byte[1024]; int len = 0; while ((len = bis.read(buff)) > 0) { bos.write(buff, 0, len); } } }二、使用ResponseEntity @GetMapping("/t2") public ResponseEntity<InputStreamResource> down2() throws Exception { InputStreamResource isr = new InputStreamResource(new FileInputStream("E:\\desktop\\1.png")); return ResponseEntity.ok() .contentType(MediaType.APPLICATION_OCTET_STREAM) .header("Content-disposition", "attachment; filename=test1.png") .body(isr); } @GetMapping("/t3") public ResponseEntity<ByteArrayResource> down3() throws Exception { byte[] bytes = Files.readAllBytes(new File("E:\\desktop\\1.png").toPath()); ByteArrayResource bar = new ByteArrayResource(bytes); return ResponseEntity.ok() .contentType(MediaType.APPLICATION_OCTET_STREAM) .header("Content-disposition", "attachment; filename=test2.png") .body(bar); }三、注意后端使用前三种的一种方式，请求方式使用非GET请求，前端使用Blob类型接收
某些情况下，在下载时需要向后端POST一些参数，这时需要前端做一定配合，将接收类型设定为Blob
@PostMapping("/t4") public ResponseEntity<ByteArrayResource> down4(String fileName, @RequestBody Map data) throws Exception { System.out.println(data); byte[] bytes = Files.readAllBytes(new File("E:\\desktop\\1.png").toPath()); ByteArrayResource bar = new ByteArrayResource(bytes); return ResponseEntity.ok() .contentType(MediaType.APPLICATION_OCTET_STREAM) .header("Content-disposition", "attachment; filename=test.png") .body(bar); }前端代码（这里使用了原生的ajax）:
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>Title</title> <script> function download() { var ajax = new XMLHttpRequest(); ajax.withCredentials = true; ajax.responseType = "blob"; const fileName = "ttt.txt"; ajax.open('post','http://localhost:7901/demo/down/file/t4?fileName=' + fileName); ajax.setRequestHeader("Content-Type","application/json;charset=utf-8"); // ajax.setRequestHeader("Accept","application/json;charset=utf-8"); ajax.send(JSON.stringify({firstName:"Bill", lastName:"Gates", age:62, eyeColor:"blue"})); ajax.onreadystatechange = function () { if (ajax.readyState==4 &&ajax.status==200) { console.log(ajax.response); const href = URL.createObjectURL(ajax.response); const a = document.createElement('a'); a.setAttribute('href', href); a.setAttribute('download', fileName); a.click(); URL.revokeObjectURL(href); } } } </script></head><body> <input type="button" value="下载" onclick="download();"/></body></html>上一篇：小程序怎么自定义导航栏，导航栏放图片、设置高度(小程序怎么自定义tabbar)
