ServletInputStream在攔截器或過濾器應用后重寫
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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中數據的代碼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(); }}; |
在攔截器種使用了request.getInputStream()或者getReader()
導致在controller中無法獲取請求參數
問題描述
在攔截器種使用了request.getInputStream()或者getReader()，然后在controller接口種使用了@requestbody ，導致controller中無法獲取入參，報錯：HttpMessageNotReadableException: Required request body is missing：
原因分析
ServletRequest中getReader()和getInputStream()只能調用一次。而又由于@RequestBody注解獲取輸出參數的方式也是根據流的方式獲取的。所以我們前面使用流獲取后，后面的@RequestBody就獲取不到對應的輸入流了。
為什么取不到輸入流了？？？因為流對應的是數據，數據放在內存中，有的是部分放在內存中。
read 一次標記一次當前位置（mark position），第二次read就從標記位置繼續讀（從內存中copy）數據。
所以這就是為什么讀了一次第二次是空了。 怎么讓它不為空呢？只要inputstream 中的pos 變成0就可以重寫讀取當前內存中的數據。
javaAPI中有一個方法public void reset() 這個方法就是可以重置pos為起始位置，但是不是所有的IO讀取流都可以調用該方法！ServletInputStream是不能調用reset方法，這就導致了只能調用一次getInputStream()。
如何處理
重寫HttpServletRequestWrapper把request保存下來，然后通過過濾器把保存下來的request再填充進去，這樣就可以多次讀取request了。
第一步：定義過濾器
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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("進入了過濾器。。。。。"); filterChain.doFilter(requestWrapper, servletResponse); } } @Override public void destroy() { }} |
第二步：重寫RequestWrapper類
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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：在啟動類中注冊過濾器
以上為個人經驗，希望能給大家一個參考，也希望大家多多支持服務器之家。
原文鏈接：https://blog.csdn.net/u011110968/article/details/80228567
