IO流可重复读问题

问题 : 传统的IO流不支持重复读取(多次读取) , 仅支持一次读取 . 在实际场景中一般会有多个方法同时调用 , 那么很有可能出现异常问题 .

场景问题 : 请求为JOSN形式的时候 , 在拦截器读取处理后 , 那么其他地方无法再次读取

解决思路 : 过滤器拦截所有路径 , 并对JSON形式的请求进行包装化处理 , 采用缓存形式保存字节码进行读取

源码

FilterConfig配置类 配置过滤器

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@Configuration
public class FilterConfig {

    @Autowired
    private XssProperties xssProperties;

    @SuppressWarnings({"rawtypes", "unchecked"})
    @Bean
    @ConditionalOnProperty(value = "xss.enabled", havingValue = "true")
    public FilterRegistrationBean xssFilterRegistration() {
        FilterRegistrationBean registration = new FilterRegistrationBean();
        registration.setDispatcherTypes(DispatcherType.REQUEST);
        registration.setFilter(new XssFilter());
        // 过滤器地址配置
        registration.addUrlPatterns(StringUtils.split(xssProperties.getUrlPatterns(), StringUtils.SEPARATOR));
        registration.setName("xssFilter");
        registration.setOrder(FilterRegistrationBean.HIGHEST_PRECEDENCE);
        // 存初始化过滤器参数
        Map<String, String> initParameters = new HashMap<String, String>();
        initParameters.put("excludes", xssProperties.getExcludes());
        registration.setInitParameters(initParameters);
        return registration;
    }

    @SuppressWarnings({"rawtypes", "unchecked"})
    @Bean
    public FilterRegistrationBean someFilterRegistration() {
        FilterRegistrationBean registration = new FilterRegistrationBean();
        registration.setFilter(new RepeatableFilter());
        registration.addUrlPatterns("/*");
        registration.setName("repeatableFilter");
        registration.setOrder(FilterRegistrationBean.LOWEST_PRECEDENCE);
        return registration;
    }

}

RepeatableFilter过滤器类

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public class RepeatableFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
        throws IOException, ServletException {
        ServletRequest requestWrapper = null;
        if (request instanceof HttpServletRequest
            && StringUtils.startsWithIgnoreCase(request.getContentType(), MediaType.APPLICATION_JSON_VALUE)) {
            requestWrapper = new RepeatedlyRequestWrapper((HttpServletRequest) request, response);
        }
        if (null == requestWrapper) {
            chain.doFilter(request, response);
        } else {
            chain.doFilter(requestWrapper, response);
        }
    }

    @Override
    public void destroy() {

    }
}

RepeatedlyRequestWrapper请求包装类

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public class RepeatedlyRequestWrapper extends HttpServletRequestWrapper {
    private final byte[] body;

    public RepeatedlyRequestWrapper(HttpServletRequest request, ServletResponse response) throws IOException {
        super(request);
        request.setCharacterEncoding(Constants.UTF8);
        response.setCharacterEncoding(Constants.UTF8);

        body = IoUtil.readBytes(request.getInputStream(), false);
    }

    @Override
    public BufferedReader getReader() throws IOException {
        return new BufferedReader(new InputStreamReader(getInputStream()));
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        final ByteArrayInputStream bais = new ByteArrayInputStream(body);
        return new ServletInputStream() {
            @Override
            public int read() throws IOException {
                return bais.read();
            }

            @Override
            public int available() throws IOException {
                return body.length;
            }

            @Override
            public boolean isFinished() {
                return false;
            }

            @Override
            public boolean isReady() {
                return false;
            }

            @Override
            public void setReadListener(ReadListener readListener) {

            }
        };
    }
}