SpringBoot过滤器获取Request的body数据

背景 

       由于在SpringBoot过滤器或者拦截器中，request中getReader()和getInputStream()只能调用一次，到controller里数据就为空了，因此会导致Controller中@RequestBody的参数无法注入而导致 400 错误

解决方案

写HttpServletRequestWrapper把request保存下来，然后通过过滤器把保存下来的request再填充进去

1. 写一个CxmHttpServletRequestWrapper包装类，继承HttpServletRequestWrapper

@Component
public class CxmHttpServletRequestWrapper extends HttpServletRequestWrapper {
 
	private byte[] requestBody = new byte[0];
	private boolean bufferFilled = false;
	
	private ConcurrentHashMap<String, String> cxmHeaders = new ConcurrentHashMap<>();
 
	public CxmHttpServletRequestWrapper(HttpServletRequest request) {
		super(request);
	}
 
	@Override
	public ServletInputStream getInputStream() throws IOException {
		return new CachedServletInputStream(getRequestBody());
	}
	
	@Override
    public String getHeader(String name) {
		String headerValue = cxmHeaders.get(name);
		if (headerValue != null) {
			return headerValue;
		} else {
			return super.getHeader(name);
		}
    }
	
	public void setHeader(String name, String value){
        this.cxmHeaders.put(name, value);
    }
 
	public byte[] getRequestBody() throws IOException {
		if (bufferFilled) {
			return Arrays.copyOf(requestBody, requestBody.length);
		}
		InputStream inputStream = super.getInputStream();
		requestBody = IOUtils.toByteArray(inputStream);
		bufferFilled = true;
		return requestBody;
	}
}

写一个CachedServletInputStream继承ServletInputStream用来处理数据

public class CachedServletInputStream extends ServletInputStream {
 
	private ByteArrayInputStream buffer;
 
	public CachedServletInputStream(byte[] contents) {
		this.buffer = new ByteArrayInputStream(contents);
	}
 
	@Override
	public int read() throws IOException {
		return buffer.read();
	}
 
	@Override
	public boolean isFinished() {
		return buffer.available() == 0;
	}
 
	@Override
	public boolean isReady() {
		return true;
	}
 
	@Override
	public void setReadListener(ReadListener listener) {
		throw new RuntimeException("Not implemented");
	}
}

2. 在过滤器中取值的时候转换成为我们自己的request包装类，并且把request传递下去

@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		HttpServletRequest requestWrapper = null;
		if (request instanceof HttpServletRequest) {
			requestWrapper = new CxmHttpServletRequestWrapper((HttpServletRequest) request);
		}
 
     chain.doFilter(requestWrapper, response);
 
}

3. 过滤器配置

@Slf4j
@Configuration
public class WebMvcConfig implements WebMvcConfigurer {
 
/**
	 * 
	 * @Title: Filters 
	 * @Description: 配置自定义的filter
	 * @return  
	 * @throws 
	 *
	 */
	@Bean
	public FilterRegistrationBean<CxmRequestValidFilter> Filters() {
	    FilterRegistrationBean<CxmRequestValidFilter> register = new FilterRegistrationBean<CxmRequestValidFilter>();
	    register.setFilter(new CxmRequestValidFilter());
	    register.addUrlPatterns("/*");
	    // 初始化filter的参数
 
	    register.addInitParameter("profile", profile);
	
	  	 register.setName("cxmRequestValidFilter");
	    return register;
	}
 
 
}