如何在Spring Boot控制器中返回图像并像文件系统一样提供服务 [英] How to return an image in Spring Boot controller and serve like a file system

问题描述

我尝试过在Stackoverflow中给出的各种方法，也许我错过了一些东西。

I've tried the various ways given in Stackoverflow, maybe I missed something.

我有一个Android客户端（其代码我无法更改），这是目前得到这样的图像：

I have an Android client (whose code I can't change) which is currently getting an image like this:

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

其中 url 是图像的位置（CDN上的静态资源）。现在我的Spring Boot API端点需要以相同的方式表现得像文件资源，以便相同的代码可以从API获取图像（Spring引导版本1.3.3）。

Where url is the location of the image (static resource on CDN). Now my Spring Boot API endpoint needs to behave like a file resource in the same way so that the same code can get images from the API (Spring boot version 1.3.3).

所以我有这个：

@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);
}

现在Android代码试图获得 http： //someurl/image1.jpg 我的日志中出现此错误：

Now when the Android code tries to get http://someurl/image1.jpg I get this error in my logs:

解决处理程序中的异常[public
org.springframework.http.ResponseEntity
com.myproject.MyController.getImage（java.lang.String）]：
org.springframework.web.HttpMediaTypeNotAcceptableException：
找不到可接受的表示

Resolving exception from handler [public org.springframework.http.ResponseEntity com.myproject.MyController.getImage(java.lang.String)]: org.springframework.web.HttpMediaTypeNotAcceptableException: Could not find acceptable representation

当我插入 http：//someurl/image1.jpg 进入浏览器。

奇怪的是，我的测试检查确定：

Oddly enough my tests check out ok:

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

如何使其表现得像服务的图像以正常方式？ （注意我无法更改android代码发送的内容类型标题）

How do I get this to behave like an image being served up in the normal way? (Note I can't change the content-type header that the android code is sending)

编辑

评论后的代码（设置内容类型，取出生成）：

Code after comments (set content type, take out produces):

@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，这似乎只是一个字符串化的垃圾（字节到字符我猜测）。在Android中它没有错误，但图像没有显示。

In a browser this just seems to give a stringified junk (byte to chars i guess). In Android it doesn't error, but the image doesn't show.

推荐答案

最后解决了这个...我不得不将 ByteArrayHttpMessageConverter 添加到我的 WebMvcConfigurerAdapter 子类：

Finally fixed this... I had to add a ByteArrayHttpMessageConverter to my WebMvcConfigurerAdapter subclass:

@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
    final ByteArrayHttpMessageConverter arrayHttpMessageConverter = new ByteArrayHttpMessageConverter();
    final List<MediaType> list = new ArrayList<>();
    list.add(MediaType.IMAGE_JPEG);
    list.add(MediaType.APPLICATION_OCTET_STREAM);
    arrayHttpMessageConverter.setSupportedMediaTypes(list);
    converters.add(arrayHttpMessageConverter);

    super.configureMessageConverters(converters);
}

这篇关于如何在Spring Boot控制器中返回图像并像文件系统一样提供服务的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！