如何更换弹簧。http。多部分。运行时最大文件大小?

在深入研究了源代码之后,我找到了一种方法来为 StandardServletMultipartResolver .

标准ServletMultipartResolver 包裹 HttpServletRequest 具有 StandardMultipartHttpServletRequest 它使用标准的servlet api实现 request.getParts() MultipartConfigElement 由设置 ServletRegistrationBean 多部件配置 因为它包含我们感兴趣的属性。

默认情况下 ServletRegistrationBean 得到 多部件配置 MultipartAutoConfiguration . 默认实现 多部件配置 不允许修改其属性,因此我们需要扩展此类以添加此类功能。进一步的实现取决于您是要根据每个请求修改参数,还是要为整个应用程序不时修改参数。

根据请求

MultipartConfigurationContext 存储特定请求的配置。 UpdateMultipartConfigurationFilter 设置给定请求的多部分属性。 UpdatableMultipartConfigElement 如果提供,则使用此信息。

public class MultipartConfigurationContext {

    private static ThreadLocal<Integer> maxFileSize = new ThreadLocal<>();

    public static void setMaxFileSize(Integer val) {
        maxFileSize.set(val);
    }

    public static Integer getMaxFileSize() {
        return maxFileSize.get();
    }

    public static void clear() {
        maxFileSize.set(null);
    }
}

public class UpdatableMultipartConfigElement extends MultipartConfigElement {

    private final long maxFileSize;

    public UpdatableMultipartConfigElement(String location, long maxFileSize, long maxRequestSize, int fileSizeThreshold) {
        super(location, maxFileSize, maxRequestSize, fileSizeThreshold);
        this.maxFileSize = maxFileSize;
    }

    @Override
    public long getMaxFileSize() {
        return MultipartConfigurationContext.getMaxFileSize() == null
                ? maxFileSize : MultipartConfigurationContext.getMaxFileSize();
    }
}

public class UpdateMultipartConfigurationFilter extends OncePerRequestFilter implements Ordered {

    // this filter must be before OrderedHiddenHttpMethodFilter
    public static final int ORDER = FilterRegistrationBean.REQUEST_WRAPPER_FILTER_MAX_ORDER - 20000;

    @Override
    public int getOrder() {
        return ORDER;
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
            throws ServletException, IOException {
        // gets file size from request if present and sets it to MultipartConfigurationContext
        MultipartConfigurationContext.setMaxFileSize(150_000);

        filterChain.doFilter(request, response);

        MultipartConfigurationContext.clear();
    }
}

@Configuration
@EnableConfigurationProperties(MultipartProperties.class)
public class MultipartConfiguration {

    private final MultipartProperties multipartProperties;

    public MultipartConfiguration(MultipartProperties multipartProperties) {
        this.multipartProperties = multipartProperties;
    }

    @Bean
    public MultipartConfigElement multipartConfigElement() {
        MultipartConfigElement multipartConfigElement = multipartProperties.createMultipartConfig();
        return new UpdatableMultipartConfigElement(multipartConfigElement.getLocation(), multipartConfigElement.getMaxFileSize(),
                multipartConfigElement.getMaxRequestSize(), multipartConfigElement.getFileSizeThreshold());
    }

    @Bean
    public UpdateMultipartConfigurationFilter updateMultipartConfigurationFilter() {
        return new UpdateMultipartConfigurationFilter();
    }
}

全球地

可更新的MultipartConfigElement 存储可以使用rest api调用在运行时更新的信息。

public class UpdatableMultipartConfigElement extends MultipartConfigElement {

    private volatile long maxFileSize = -1;

    public UpdatableMultipartConfigElement(String location, long maxFileSize, long maxRequestSize, int fileSizeThreshold) {
        super(location, maxFileSize, maxRequestSize, fileSizeThreshold);
    }

    @Override
    public long getMaxFileSize() {
        return maxFileSize == -1 ? super.getMaxFileSize() : maxFileSize;
    }

    public void setMaxFileSize(long maxFileSize) {
        this.maxFileSize = maxFileSize;
    }
}

@Configuration
@EnableConfigurationProperties(MultipartProperties.class)
public class MultipartConfiguration {

    private final MultipartProperties multipartProperties;

    public MultipartConfiguration(MultipartProperties multipartProperties) {
        this.multipartProperties = multipartProperties;
    }

    @Bean
    public MultipartConfigElement multipartConfigElement() {
        MultipartConfigElement multipartConfigElement = multipartProperties.createMultipartConfig();
        return new UpdatableMultipartConfigElement(multipartConfigElement.getLocation(), multipartConfigElement.getMaxFileSize(),
                multipartConfigElement.getMaxRequestSize(), multipartConfigElement.getFileSizeThreshold());
    }
}

@RestController
public class ConfigurationController {

    @Autowired
    private UpdatableMultipartConfigElement updatableMultipartConfigElement;

    @RequestMapping("/configuration")
    public void configuration(@RequestParam("maxFileSize") long maxFileSize) {
        updatableMultipartConfigElement.setMaxFileSize(maxFileSize);
    }

}