RequestBody只能读取一次的问题

2024-07-02 18:55| 来源: 网络整理| 查看: 265

一、为什么只能读一次

原因很简单：因为是流。想想看，java中的流也是只能读一次，因为读完之后，position就到末尾了。

二、解决办法

思路：第一次读的时候，把流数据暂存起来。后面需要的时候，直接把暂存的数据返回出去。

实现逻辑：

自定义一个HttpServletRequestWrapper，覆写getInputStream()和getReader()方法。增加一个Filter，在doFilter()中启用自定义的Wrapper 三、代码

1、自定义的Wrapper

import javax.servlet.ReadListener; import javax.servlet.ServletInputStream; import javax.servlet.ServletRequest; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletRequestWrapper; import java.io.BufferedReader; import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.nio.charset.Charset; public class BodyReaderHttpServletRequestWrapper extends HttpServletRequestWrapper { private final byte[] body; public BodyReaderHttpServletRequestWrapper(HttpServletRequest request) throws IOException { super(request); String sessionStream = getBodyString(request); body = sessionStream.getBytes(Charset.forName("UTF-8")); } private String getBodyString(ServletRequest request) throws IOException { StringBuilder sb = new StringBuilder(); InputStream ins = request.getInputStream(); try (BufferedReader isr = new BufferedReader(new InputStreamReader(ins, Charset.forName("UTF-8")));) { String line = ""; while ((line = isr.readLine()) != null) { sb.append(line); } } catch (IOException e) { throw e; } return sb.toString(); } @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 boolean isFinished() { return bais.available() == 0; } @Override public boolean isReady() { return true; } @Override public void setReadListener(ReadListener readListener) { } }; } }

2、加个Filter来启用wrapper

import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.annotation.WebFilter; import javax.servlet.http.HttpServletRequest; import java.io.IOException; // 启用Filter需要在Springboot的启动类加@ServletComponentScan @WebFilter(filterName = "bodyReaderFilter", urlPatterns = "/*") public class BodyReaderFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest; ServletRequest requestWrapper = new BodyReaderHttpServletRequestWrapper(httpServletRequest); filterChain.doFilter(requestWrapper, servletResponse); } @Override public void destroy() { } }

【本文地址】

公司简介

联系我们