ServletInputStream在拦截器或过滤器应用后重写
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ServletInputStream inputStream = super.getInputStream();StringBuilder sb = new StringBuilder();BufferedReader reader = null;try { reader = new BufferedReader(new InputStreamReader(servletInputStream, Charset.forName("UTF-8"))); String line = ""; while ((line = reader.readLine()) != null) { sb.append(line); }} catch (IOException e) { e.printStackTrace();} finally { if (servletInputStream != null) { try { servletInputStream.close(); } catch (IOException e) { e.printStackTrace(); } } if (reader != null) { try { reader.close(); } catch (IOException e) { e.printStackTrace(); } }}//使用ServletInputStream中数据的代码byte[] bytes = sb.getBytes("UTF-8");final ByteArrayInputStream bais = new ByteArrayInputStream(bytes);return new ServletInputStream() { @Override public boolean isFinished() { return false; } @Override public boolean isReady() { return false; } @Override public void setReadListener(ReadListener readListener) { } @Override public int read() throws IOException { return bais.read(); }}; |
在拦截器种使用了request.getInputStream()或者getReader()
导致在controller中无法获取请求参数
问题描述
在拦截器种使用了request.getInputStream()或者getReader()，然后在controller接口种使用了@requestbody ，导致controller中无法获取入参，报错：HttpMessageNotReadableException: Required request body is missing：
原因分析
ServletRequest中getReader()和getInputStream()只能调用一次。而又由于@RequestBody注解获取输出参数的方式也是根据流的方式获取的。所以我们前面使用流获取后，后面的@RequestBody就获取不到对应的输入流了。
为什么取不到输入流了？？？因为流对应的是数据，数据放在内存中，有的是部分放在内存中。
read 一次标记一次当前位置（mark position），第二次read就从标记位置继续读（从内存中copy）数据。
所以这就是为什么读了一次第二次是空了。 怎么让它不为空呢？只要inputstream 中的pos 变成0就可以重写读取当前内存中的数据。
javaAPI中有一个方法public void reset() 这个方法就是可以重置pos为起始位置，但是不是所有的IO读取流都可以调用该方法！ServletInputStream是不能调用reset方法，这就导致了只能调用一次getInputStream()。
如何处理
重写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，这样就可以多次读取request了。
第一步：定义过滤器
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import javax.servlet.*;import javax.servlet.annotation.WebFilter;import javax.servlet.http.HttpServletRequest;import java.io.IOException; @WebFilter(urlPatterns = "/*", filterName = "channelFilter")public class ChannelFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { ServletRequest requestWrapper = null; if (servletRequest instanceof HttpServletRequest) { requestWrapper = new RequestWrapper((HttpServletRequest) servletRequest); } if (requestWrapper == null) { filterChain.doFilter(servletRequest, servletResponse); } else { System.out.println("进入了过滤器。。。。。"); filterChain.doFilter(requestWrapper, servletResponse); } } @Override public void destroy() { }} |
第二步：重写RequestWrapper类
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import javax.servlet.ReadListener;import javax.servlet.ServletInputStream;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;import java.io.*; public class RequestWrapper extends HttpServletRequestWrapper { private final String body; public RequestWrapper(HttpServletRequest request) { super(request); StringBuilder stringBuilder = new StringBuilder(); BufferedReader bufferedReader = null; InputStream inputStream = null; try { inputStream = request.getInputStream(); if (inputStream != null) { bufferedReader = new BufferedReader(new InputStreamReader(inputStream)); char[] charBuffer = new char[128]; int bytesRead = -1; while ((bytesRead = bufferedReader.read(charBuffer)) > 0) { stringBuilder.append(charBuffer, 0, bytesRead); } } else { stringBuilder.append(""); } } catch (IOException ex) { } finally { if (inputStream != null) { try { inputStream.close(); } catch (IOException e) { e.printStackTrace(); } } if (bufferedReader != null) { try { bufferedReader.close(); } catch (IOException e) { e.printStackTrace(); } } } body = stringBuilder.toString(); } @Override public ServletInputStream getInputStream() throws IOException { final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes()); ServletInputStream servletInputStream = new ServletInputStream() { @Override public boolean isFinished() { return false; } @Override public boolean isReady() { return false; } @Override public void setReadListener(ReadListener readListener) { } @Override public int read() throws IOException { return byteArrayInputStream.read(); } }; return servletInputStream; } @Override public BufferedReader getReader() throws IOException { return new BufferedReader(new InputStreamReader(this.getInputStream())); } public String getBody() { return this.body; }} |
第三步：在启动类中注册过滤器
以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/u011110968/article/details/80228567
