SpringBoot之HandlerInterceptor拦截器的使用（三）@RequestBody获取请求参数解决: Stream closed

现在开发的项目是基于SpringBoot的maven项目，拦截器的使用很多时候是必不可少的，当有需要需要你对body中的值进行校验，例如加密验签、防重复提交、内容校验等等。

1.问题

当你开开心心的在拦截器中通过();获取到body中的信息后，你会发现你在controller中使用了@RequestBody注解获取参数报如下错误

I/O error while reading input message; nested exception is : Stream closed
: I/O error while reading input message; nested exception is : Stream closed
	at (:229)
	at (:150)
	at (:128)
	at (:121)
	at (:158)
	at (:128)
	at (:97)
	at (:827)
	at (:738)
	at (:85)
	at (:967)
	at (:901)
	at (:970)
	at (:872)
	at (:661)
	at (:846)
	at (:742)
	at (:231)
	at (:166)
	at (:55)
	at (:107)
	at (:193)
	at (:166)
	at (:96)
	at (:107)
	at (:193)
	at (:166)
	at (:107)
	at (:193)
	at (:166)
	at (:110)
	at (:107)
	at (:193)
	at (:166)

2. 解决思路

IO流关闭只能读取一次，接下来我们就开始解决这个BUG，有两种大的方向：

这个需求咱不做了，特么有本事就把东西都放在请求头里面传过来；

解决流只能读取一次的问题，让它可以被多次重复读取；

考虑到生活还要继续，妻儿老小在家等着我回去告诉他们晚上吃冷面还是鸡，要这需求不给搞定那也只能去打包收拾东西滚蛋，回家路上顺便卖点血换钱了，我选择了第二种。

3.问题解决

最简单的方案就是先读取流，然后在将流写进去就行了。

3.1 引入包

<dependency>
	<groupId></groupId>
	<artifactId>tomcat-embed-core</artifactId>
	<version>8.5.15</version>
</dependency>

3.2 新建HttpHelper （用于读取Body）

package ;

import ;
import ;
import ;
import ;
import ;
import ;

public class HttpHelper {
    public static String getBodyString(HttpServletRequest request) throws IOException {
        StringBuilder sb = new StringBuilder();
        InputStream inputStream = null;
        BufferedReader reader = null;
        try {
            inputStream = ();
            reader = new BufferedReader(new InputStreamReader(inputStream, ("UTF-8")));
            String line = "";
            while ((line = ()) != null) {
                (line);
            }
        } catch (IOException e) {
            ();
        } finally {
            if (inputStream != null) {
                try {
                    ();
                } catch (IOException e) {
                    ();
                }
            }
            if (reader != null) {
                try {
                    ();
                } catch (IOException e) {
                    ();
                }
            }
        }
        return ();
    }
}

3.3 新建RequestReaderHttpServletRequestWrapper（防止流丢失）

package ;

import ;
import ;
import ;
import ;
import ;

import ;
import ;
import ;
import ;

public class RequestReaderHttpServletRequestWrapper extends HttpServletRequestWrapper{

    private final byte[] body;

    public RequestReaderHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
        super(request);
        body = (request).getBytes(("UTF-8"));
    }

    @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 ();
            }

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

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

            @Override
            public void setReadListener(ReadListener readListener) {

            }
        };
    }
}

3.4 新建HttpServletRequestReplacedFilter(过滤器)

package ;


import .*;
import ;
import ;

public class HttpServletRequestReplacedFilter implements Filter {
    @Override
    public void destroy() {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain) throws IOException, ServletException {
        ServletRequest requestWrapper = null;
        if(request instanceof HttpServletRequest) {
            requestWrapper = new RequestReaderHttpServletRequestWrapper((HttpServletRequest) request);
        }
        //获取请求中的流如何，将取出来的字符串，再次转换成流，然后把它放入到新request对象中。
        // 在方法中传递新的request对象
        if(requestWrapper == null) {
            (request, response);
        } else {
            (requestWrapper, response);
        }
    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {

    }
}

最后我们只需要在中加上如下代码注入过滤器即可

@Bean
	public FilterRegistrationBean httpServletRequestReplacedRegistration() {
		FilterRegistrationBean registration = new FilterRegistrationBean();
		(new HttpServletRequestReplacedFilter());
		("/*");
        ("paramName", "paramValue");
		("httpServletRequestReplacedFilter");
		(1);
		return registration;
	}

4.测试

如下代码即可在拦截其中获取body且保证了controller中依旧可以再次获取

 (request);

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