我从DB获取图像数据(byte[]
)。如何在@ResponseBody
中返回此图片?
修改
我没有@ResponseBody
使用HttpServletResponse
作为方法参数:
@RequestMapping("/photo1")
public void photo(HttpServletResponse response) throws IOException {
response.setContentType("image/jpeg");
InputStream in = servletContext.getResourceAsStream("/images/no_image.jpg");
IOUtils.copy(in, response.getOutputStream());
}
将@ResponseBody
与已注册的org.springframework.http.converter.ByteArrayHttpMessageConverter
转换器一起使用@Sid表示对我不起作用:(。
@ResponseBody
@RequestMapping("/photo2")
public byte[] testphoto() throws IOException {
InputStream in = servletContext.getResourceAsStream("/images/no_image.jpg");
return IOUtils.toByteArray(in);
}
答案 0 :(得分:92)
如果您使用的是Spring版本的3.1或更新版本,则可以在@RequestMapping
注释中指定“生成”。以下示例适用于我的开箱即用。如果您启用了网络mvc(@EnableWebMvc
),则无需注册转换器或其他任何内容。
@ResponseBody
@RequestMapping(value = "/photo2", method = RequestMethod.GET, produces = MediaType.IMAGE_JPEG_VALUE)
public byte[] testphoto() throws IOException {
InputStream in = servletContext.getResourceAsStream("/images/no_image.jpg");
return IOUtils.toByteArray(in);
}
答案 1 :(得分:71)
使用Spring 4.1及更高版本,您可以非常简单地返回任何内容(例如图片,pdf,文档,jar,拉链等),而无需任何额外的依赖项。例如,以下可能是从MongoDB GridFS返回用户个人资料图片的方法:
@RequestMapping(value = "user/avatar/{userId}", method = RequestMethod.GET)
@ResponseBody
public ResponseEntity<InputStreamResource> downloadUserAvatarImage(@PathVariable Long userId) {
GridFSDBFile gridFsFile = fileService.findUserAccountAvatarById(userId);
return ResponseEntity.ok()
.contentLength(gridFsFile.getLength())
.contentType(MediaType.parseMediaType(gridFsFile.getContentType()))
.body(new InputStreamResource(gridFsFile.getInputStream()));
}
需要注意的事项:
使用InputStreamResource作为返回类型的ResponseEntity
ResponseEntity构建器样式创建
使用此方法,您不必担心HttpServletResponse中的自动装配,抛出IOException或复制流数据。
答案 2 :(得分:57)
除了注册ByteArrayHttpMessageConverter
之外,您可能还想使用ResponseEntity
代替@ResponseBody
。以下代码适用于我:
@RequestMapping("/photo2")
public ResponseEntity<byte[]> testphoto() throws IOException {
InputStream in = servletContext.getResourceAsStream("/images/no_image.jpg");
final HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.IMAGE_PNG);
return new ResponseEntity<byte[]>(IOUtils.toByteArray(in), headers, HttpStatus.CREATED);
}
答案 3 :(得分:16)
通过使用Spring 3.1.x和3.2.x,您应该这样做:
控制器方法:
@RequestMapping("/photo2")
public @ResponseBody byte[] testphoto() throws IOException {
InputStream in = servletContext.getResourceAsStream("/images/no_image.jpg");
return IOUtils.toByteArray(in);
}
servlet-context.xml文件中的mvc注释:
<mvc:annotation-driven>
<mvc:message-converters>
<bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter">
<property name="supportedMediaTypes">
<list>
<value>image/jpeg</value>
<value>image/png</value>
</list>
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>
答案 4 :(得分:11)
除了几个答案之外还有一些指针(Spring 4.1)。
如果您的ResponseEntity
内@ResponseBody
效果良好,则您的WebMvcConfig中没有配置任何消息转换器。
如果你这样做,即你使用MappingJackson2HttpMessageConverter
配置ResponseEntity
(就像我一样),则返回org.springframework.http.converter.HttpMessageNotWritableException
。
在这种情况下,唯一可行的解决方案是将byte[]
包裹在@ResponseBody
中,如下所示:
@RequestMapping(value = "/get/image/{id}", method=RequestMethod.GET, produces = MediaType.IMAGE_PNG_VALUE)
public @ResponseBody byte[] showImageOnId(@PathVariable("id") String id) {
byte[] b = whatEverMethodUsedToObtainBytes(id);
return b;
}
在这种情况下,请记住在WebMvcConfig中正确配置messageconverters(并添加ByteArrayHttpMessageConverer
),如下所示:
@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
converters.add(mappingJackson2HttpMessageConverter());
converters.add(byteArrayHttpMessageConverter());
}
@Bean
public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
converter.setObjectMapper(objectMapper);
return converter;
}
@Bean
public ByteArrayHttpMessageConverter byteArrayHttpMessageConverter() {
ByteArrayHttpMessageConverter arrayHttpMessageConverter = new ByteArrayHttpMessageConverter();
arrayHttpMessageConverter.setSupportedMediaTypes(getSupportedMediaTypes());
return arrayHttpMessageConverter;
}
private List<MediaType> getSupportedMediaTypes() {
List<MediaType> list = new ArrayList<MediaType>();
list.add(MediaType.IMAGE_JPEG);
list.add(MediaType.IMAGE_PNG);
list.add(MediaType.APPLICATION_OCTET_STREAM);
return list;
}
答案 5 :(得分:6)
在您的应用程序上下文中声明一个AnnotationMethodHandlerAdapter和registerByteArrayHttpMessageConverter:
<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
<property name="messageConverters">
<util:list>
<bean id="byteArrayMessageConverter" class="org.springframework.http.converter.ByteArrayHttpMessageConverter"/>
</util:list>
</property>
</bean>
还在处理程序方法中为您的响应设置适当的内容类型。
答案 6 :(得分:6)
@RequestMapping(value = "/get-image",method = RequestMethod.GET)
public ResponseEntity<byte[]> getImage() throws IOException {
RandomAccessFile f = new RandomAccessFile("/home/vivex/apache-tomcat-7.0.59/tmpFiles/1.jpg", "r");
byte[] b = new byte[(int)f.length()];
f.readFully(b);
final HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.IMAGE_PNG);
return new ResponseEntity<byte[]>(b, headers, HttpStatus.CREATED);
}
为我工作。
答案 7 :(得分:4)
我喜欢这个:
private ResourceLoader resourceLoader = new DefaultResourceLoader();
@ResponseBody
@RequestMapping(value = "/{id}", produces = "image/bmp")
public Resource texture(@PathVariable("id") String id) {
return resourceLoader.getResource("classpath:images/" + id + ".bmp");
}
将媒体类型更改为您拥有的图像格式。
答案 8 :(得分:3)
春天4,这对我有用。
@RequestMapping(value = "/image/{id}", method = RequestMethod.GET)
public void findImage(@PathVariable("id") String id, HttpServletResponse resp){
final Foto anafoto = <find object>
resp.reset();
resp.setContentType(MediaType.IMAGE_JPEG_VALUE);
resp.setContentLength(anafoto.getImage().length);
final BufferedInputStream in = new BufferedInputStream(new ByteArrayInputStream(anafoto.getImageInBytes()));
try {
FileCopyUtils.copy(in, resp.getOutputStream());
resp.flushBuffer();
} catch (final IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
答案 9 :(得分:2)
非答案对我有用,所以我设法做到了这样:
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.parseMediaType("your content type here"));
headers.set("Content-Disposition", "attachment; filename=fileName.jpg");
headers.setContentLength(fileContent.length);
return new ResponseEntity<>(fileContent, headers, HttpStatus.OK);
设置Content-Disposition
标题我可以在我的方法上下载带有@ResponseBody
注释的文件。
答案 10 :(得分:1)
这就是我使用Spring Boot和Guava的方式:
@RequestMapping(value = "/getimage", method = RequestMethod.GET, produces = MediaType.IMAGE_JPEG_VALUE)
public void getImage( HttpServletResponse response ) throws IOException
{
ByteStreams.copy( getClass().getResourceAsStream( "/preview-image.jpg" ), response.getOutputStream() );
}
答案 11 :(得分:0)
在春季4,您不需要对bean进行任何更改。只将您的退货类型标记为@ResponseBody。
示例: - 强>
@RequestMapping(value = "/image/{id}")
public @ResponseBody
byte[] showImage(@PathVariable Integer id) {
byte[] b;
/* Do your logic and return
*/
return b;
}
答案 12 :(得分:0)
我认为您可能需要一项服务来存储文件上传并获取该文件。 查看here
的更多详情1)创建存储服务
@Service
public class StorageService {
Logger log = LoggerFactory.getLogger(this.getClass().getName());
private final Path rootLocation = Paths.get("upload-dir");
public void store(MultipartFile file) {
try {
Files.copy(file.getInputStream(), this.rootLocation.resolve(file.getOriginalFilename()));
} catch (Exception e) {
throw new RuntimeException("FAIL!");
}
}
public Resource loadFile(String filename) {
try {
Path file = rootLocation.resolve(filename);
Resource resource = new UrlResource(file.toUri());
if (resource.exists() || resource.isReadable()) {
return resource;
} else {
throw new RuntimeException("FAIL!");
}
} catch (MalformedURLException e) {
throw new RuntimeException("FAIL!");
}
}
public void deleteAll() {
FileSystemUtils.deleteRecursively(rootLocation.toFile());
}
public void init() {
try {
Files.createDirectory(rootLocation);
} catch (IOException e) {
throw new RuntimeException("Could not initialize storage!");
}
}
}
2)创建Rest Controller以上传和获取文件
@Controller
public class UploadController {
@Autowired
StorageService storageService;
List<String> files = new ArrayList<String>();
@PostMapping("/post")
public ResponseEntity<String> handleFileUpload(@RequestParam("file") MultipartFile file) {
String message = "";
try {
storageService.store(file);
files.add(file.getOriginalFilename());
message = "You successfully uploaded " + file.getOriginalFilename() + "!";
return ResponseEntity.status(HttpStatus.OK).body(message);
} catch (Exception e) {
message = "FAIL to upload " + file.getOriginalFilename() + "!";
return ResponseEntity.status(HttpStatus.EXPECTATION_FAILED).body(message);
}
}
@GetMapping("/getallfiles")
public ResponseEntity<List<String>> getListFiles(Model model) {
List<String> fileNames = files
.stream().map(fileName -> MvcUriComponentsBuilder
.fromMethodName(UploadController.class, "getFile", fileName).build().toString())
.collect(Collectors.toList());
return ResponseEntity.ok().body(fileNames);
}
@GetMapping("/files/{filename:.+}")
@ResponseBody
public ResponseEntity<Resource> getFile(@PathVariable String filename) {
Resource file = storageService.loadFile(filename);
return ResponseEntity.ok()
.header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + file.getFilename() + "\"")
.body(file);
}
}
答案 13 :(得分:0)
您应该在响应中指定媒体类型。我正在使用带有produce = MediaType.IMAGE_JPEG_VALUE的@GetMapping注释。 @RequestMapping也会一样。
@GetMapping(value="/current/chart",produces = MediaType.IMAGE_JPEG_VALUE)
@ResponseBody
public byte[] getChart() {
return ...;
}
如果没有媒体类型,很难猜到实际返回的内容(包括任何读取代码的人,浏览器,当然还有Spring本身)。 byte []不是特定的。从byte []确定媒体类型的唯一方法是嗅探和猜测。
提供媒体类型只是最佳做法
答案 14 :(得分:0)
将产品与 MediaType.IMAGE_JPEG_VALUE 一起使用时,请确保您返回的是 byte[],而不是 Byte[]。很奇怪,但 spring 无法转换它并引发异常:找不到转换器。