在项目中经常出现多次读取HTTP请求体的情况,这时候可能就会报错,原因是读取HTTP请求体的操作,最终都要调用HttpServletRequest的getInputStream()方法和getReader()方法,而这两个方法总共只能被调用一次,第二次调用就会报错,那如何解决这个问题呢?以若依框架中的RepeatableFilter为例进行说明。
将HttpServletRequest的字节流的数据,保存到一个变量中,重写getInputStream()方法和getReader()方法,从变量中读取数据,返回给调用者。
RepeatableFilter
package com.ruoyi.common.filter; import java.io.IOException; 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.http.HttpServletRequest; import org.springframework.http.MediaType; import com.ruoyi.common.utils.StringUtils; public class RepeatableFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { ServletRequest requestWrapper = null; if (request instanceof HttpServletRequest && StringUtils.equalsAnyIgnoreCase(request.getContentType(), MediaType.APPLICATION_JSON_VALUE, MediaType.APPLICATION_JSON_UTF8_VALUE)) { requestWrapper = new RepeatedlyRequestWrapper((HttpServletRequest) request, response); } if (null == requestWrapper) { chain.doFilter(request, response); } else { chain.doFilter(requestWrapper, response); } } @Override public void destroy() { } }
RepeatedlyRequestWrapper
package com.ruoyi.common.filter; import java.io.BufferedReader; import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStreamReader; import javax.servlet.ReadListener; import javax.servlet.ServletInputStream; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletRequestWrapper; import com.ruoyi.common.utils.http.HttpHelper; /** * 构建可重复读取inputStream的request * * @author ruoyi */ public class RepeatedlyRequestWrapper extends HttpServletRequestWrapper { private final byte[] body; public RepeatedlyRequestWrapper(HttpServletRequest request, ServletResponse response) throws IOException { super(request); request.setCharacterEncoding("UTF-8"); response.setCharacterEncoding("UTF-8"); body = HttpHelper.getBodyString(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 bais.read(); } @Override public boolean isFinished() { return false; } @Override public boolean isReady() { return false; } @Override public void setReadListener(ReadListener readListener) { } }; } }
然后再将filter注册进spring即可:
package com.ruoyi.framework.config; import java.util.HashMap; import java.util.Map; import javax.servlet.DispatcherType; import org.springframework.beans.factory.annotation.Value; import org.springframework.boot.web.servlet.FilterRegistrationBean; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import com.ruoyi.common.filter.RepeatableFilter; import com.ruoyi.common.filter.XssFilter; import com.ruoyi.common.utils.StringUtils; /** * Filter配置 * * @author ruoyi */ @Configuration public class FilterConfig { @Value("${xss.enabled}") private String enabled; @Value("${xss.excludes}") private String excludes; @Value("${xss.urlPatterns}") private String urlPatterns; @SuppressWarnings({ "rawtypes", "unchecked" }) @Bean public FilterRegistrationBean xssFilterRegistration() { FilterRegistrationBean registration = new FilterRegistrationBean(); registration.setDispatcherTypes(DispatcherType.REQUEST); registration.setFilter(new XssFilter()); registration.addUrlPatterns(StringUtils.split(urlPatterns, ",")); registration.setName("xssFilter"); registration.setOrder(FilterRegistrationBean.HIGHEST_PRECEDENCE); Map<String, String> initParameters = new HashMap<String, String>(); initParameters.put("excludes", excludes); initParameters.put("enabled", enabled); registration.setInitParameters(initParameters); return registration; } @SuppressWarnings({ "rawtypes", "unchecked" }) @Bean public FilterRegistrationBean someFilterRegistration() { FilterRegistrationBean registration = new FilterRegistrationBean(); registration.setFilter(new RepeatableFilter()); registration.addUrlPatterns("/*"); registration.setName("repeatableFilter"); registration.setOrder(FilterRegistrationBean.LOWEST_PRECEDENCE); return registration; } }