如何在Spring Boot controller中返回映像并像文件系统一样服务

Question

我已经尝试了Stackoverflow中给出的各种方法，也许我错过了什么。

HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.connect();

@ResponseBody
@RequestMapping(value = "/Image/{id:.+}", method = RequestMethod.GET, consumes = MediaType.ALL_VALUE, produces = MediaType.IMAGE_JPEG_VALUE)
public ResponseEntity<byte[]> getImage(@PathVariable("id")String id) {
    byte[] image = imageService.getImage(id);  //this just gets the data from a database
    return ResponseEntity.ok(image);
}

Response response = given()
            .pathParam("id", "image1.jpg")
            .when()
            .get("MyController/Image/{id}");

assertEquals(HttpStatus.OK.value(), response.getStatusCode());
byte[] array = response.asByteArray(); //byte array is identical to test image

注释后的代码（设置内容类型，取出产生):

@RequestMapping(value = "/Image/{id:.+}", method = RequestMethod.GET, consumes = MediaType.ALL_VALUE)
public ResponseEntity<byte[]> getImage(@PathVariable("id")String id, HttpServletResponse response) {
    byte[] image = imageService.getImage(id);  //this just gets the data from a database
    response.setContentType(MediaType.IMAGE_JPEG_VALUE);
    return ResponseEntity.ok(image);
}

在浏览器中，这似乎只是给了一个字符串化的垃圾（我猜是字节到字符）。在Android中，它不会出错，但图像不会显示。

Answer 1

我相信这应该行得通：

@RequestMapping(value = "/Image/{id:.+}", method = RequestMethod.GET)
public ResponseEntity<byte[]> getImage(@PathVariable("id") String id) {
    byte[] image = imageService.getImage(id);
    return ResponseEntity.ok().contentType(MediaType.IMAGE_JPEG).body(image);
}

请注意，内容类型是为ResponseEntity设置的，而不是直接为HttpServletResponse设置的。