SpringMVC 接收方法的參數自定義轉換

SpringMVC 接收方法的參數自定義轉換，下面例子實現客戶端發送圖片的Base64數據，服務器轉換爲自定義的對象。

1. 首先，須要配置自定義的轉換器。

<mvc:annotation-driven>
    <mvc:argument-resolvers>
       <bean class="com.mumu.support.spring.Base64ToFileConverter"></bean>
    </mvc:argument-resolvers>
</mvc:annotation-driven>

 

2. 添加註解RequestBase64和實體類Base64File。並實現Base64ToFileConverter（實現org.springframework.web.method.support.HandlerMethodArgumentResolver接口）

        1） 註解RequestBase64

@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface RequestBase64 {

}

        2） 實體類Base64File

public class Base64File {
	
	private String imageType;
	private byte[] content;
	
	public Base64File() {
	}
	
	public Base64File(String imageType, byte[] content) {
		super();
		this.imageType = imageType;
		this.content = content;
	}

	public boolean isEmpty() {
		return ArrayUtils.isEmpty(content);
	}

	public long getSize() {
		return content != null? content.length:0L;
	}

	public byte[] getBytes() throws IOException {
		return content;
	}
	
	public String getImageType() {
		return imageType;
	}

	public InputStream getInputStream() throws IOException {
		ByteArrayInputStream bais = new ByteArrayInputStream(content);
		return bais;
	}

	public void transferTo(File dest) throws IOException, IllegalStateException {
		if(isEmpty()){
			return;
		}
		try(FileOutputStream fos = new FileOutputStream(dest);){
			fos.write(content, 0, content.length);
		}
	}

}

        3） Base64ToFileConverter

public class Base64ToFileConverter implements HandlerMethodArgumentResolver{
	
	private static Pattern pattern = Pattern.compile("data:([^;]*);base64,(.+)", Pattern.CASE_INSENSITIVE);
	
	public Base64ToFileConverter(){
	}

	@Override
	public boolean supportsParameter(MethodParameter parameter) {
		return parameter.hasParameterAnnotation(RequestBase64.class);
	}

	@Override
	public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
			NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
		String[] values = webRequest.getParameterValues(parameter.getParameterName());
		if(ArrayUtils.isNotEmpty(values)){
			
			if(parameter.getParameterType().isAssignableFrom(Base64File.class)){
				return toContent(values[0]);
			}else if(parameter.getParameterType().isAssignableFrom(List.class)){
				List<Base64File> list = new ArrayList<>(values.length);
				for(String value : values){
					list.add(toContent(value));
				}
				return list;
			}else if(parameter.getParameterType().isArray()){
				Base64File[] bfs = new Base64File[values.length];
				int index = 0;
				for(String value : values){
					bfs[index++] = toContent(value);
				}
				return bfs;
			}
		}

		return null;
	}

	private Base64File toContent(String value){
		sun.misc.BASE64Decoder decoder = new sun.misc.BASE64Decoder();  
        try   
        {  
        	Matcher matcher = pattern.matcher(value);
        	if(matcher.find()){
        		String imageType = matcher.group(1);
        		String content = matcher.group(2);
        		
        		//Base64解碼  
                byte[] b = decoder.decodeBuffer(content);  
                return new Base64File(imageType, b);
        	}
        	
        	return null;
        }catch(Exception e){
        	throw new I18NIllegalArgumentException(e);
        }
	}
	
	public static void main(String[] args) {
		String value = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABwAAAAeCAIAAACwp+nIAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAADxSURBVEhL7ZU7DoMwEESXVNBRUsKtuAHcgmNAyS3gZtCRER5FkYw/66AUUV4BK2OeZmWxZMdxyN08eL+VH5Cu69o0TeYAj+Z55lYbHNQldV1zh4M8z7nVwpm06zpWDvZ9Z2VDeRzjOPK1E65aKKTLspRlSZ9I3/d8YKGQVlVFn8i2bVy9Ilb63rgnoyFW+orZti2X3ERJ32P6GzdESVUxQViqjQnCUm1MEJAmxAQBaUJMEJj8GEimQExMEFMH8c3TaZpYnTOJVQwm8CVpvQNf+0VRmPmm6h342h+GAVd86brecRKepMl898f3CX/p3Yg8AZMYt/pV+plfAAAAAElFTkSuQmCC";
		Matcher matcher = pattern.matcher(value);
    	if(matcher.find()){
    		String imageType = matcher.group(1);
    		String content = matcher.group(2);
    		
    		System.out.println(imageType + "   " + content);
    	}
	}
}

3. Controller中方法實現

@RequestMapping(value = "/testing", method = RequestMethod.POST)
	@ResponseBody
	public ResultVO testing(@RequestBase64 Base64File file, @RequestBase64 List<Base64File> file2) {
			try {
				System.out.println(Arrays.toString(file.getBytes()));
				
				System.out.println("=============================");
				file2.stream().forEach(new Consumer<Base64File>() {

					@Override
					public void accept(Base64File t) {
						try {
							System.out.println(Arrays.toString(t.getBytes()));
						} catch (IOException e) {
							e.printStackTrace();
						}
					}
				});
				
				file.transferTo(new File("d:/test.jpg"));
			} catch (IOException e) {
				e.printStackTrace();
			}
		return ResultVO.successVO();
	}

 

注意事項： 參數前面不能加@RequestParam，不然org.springframework.web.method.annotation.RequestParamMethodArgumentResolver會處理參數解析