Spring多次request.getReader()

ServletRequest的getReader和getInputStream只能调用一次

开发中遇到一个需求，在拦截器中拦截前端body里传过来的token并解析存入ThreadLocal中，方便使用，但是前端传过来的数据带有\，一般解析不到参数，也需要获取body中的数据将\去掉，才能转成对象。

但是，使用@RequestBody报错，因为getReader和getInputStream只能调用一次，要解决这个问题则需要将服务器创建的request再次封装，使之可以多次调用getReader和getInputStream

多方查找发现Spring自带了一个对HttpServletRequestWrapper的重写

1、继承HttpServletRequestWrapper封装 request请求，将body中的数据保存在 byte[] body中

import org.apache.commons.lang3.StringUtils;

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
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.InputStreamReader;
import java.nio.charset.StandardCharsets;

public class BodyReaderHttpServletRequestWrapper extends HttpServletRequestWrapper {
    
    

    private byte[] body;

    public BodyReaderHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
    
    
        super(request);
        BufferedReader br = null;
        try {
    
    
            try {
    
    
                br = new BufferedReader(new InputStreamReader(request.getInputStream(), StandardCharsets.UTF_8));
            } catch (IOException e) {
    
    
                e.printStackTrace();
            }
            String str;
            StringBuilder wholeStr = new StringBuilder();
            while ((str = br.readLine()) != null) {
    
    
                wholeStr.append(str);
            }
            if (StringUtils.isNotEmpty(wholeStr.toString())) {
    
    
                body = wholeStr.toString().getBytes(StandardCharsets.UTF_8);
            }
        } catch (IOException e) {
    
    
            e.printStackTrace();
        }
    }

    @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) {
    
    

            }

        };
    }

    public void setInputStream(byte[] body) {
    
    
        this.body = body;
    }
}

2、编写过滤器并使用注解使之生效

import com.ucdt.aftersale.util.BodyReaderHttpServletRequestWrapper;
import lombok.extern.slf4j.Slf4j;

import javax.servlet.FilterConfig;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

@Slf4j
@WebFilter(filterName = "RequestWrapperFilter", urlPatterns = "/sys/*")
public class RequestWrapperFilter implements Filter {
    
    


    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    
    
        Filter.super.init(filterConfig);
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    
    
        ServletRequest requestWrapper = null;
        if (request instanceof HttpServletRequest) {
    
    
            requestWrapper = new BodyReaderHttpServletRequestWrapper((HttpServletRequest) request);
        }
        if (null == requestWrapper) {
    
    
            log.error("过滤器包装request失败!将返回原来的request");
            chain.doFilter(request, response);
        } else {
    
    
            log.info("过滤器包装request成功");
            chain.doFilter(requestWrapper, response);
        }
    }

    @Override
    public void destroy() {
    
    
        Filter.super.destroy();
    }
}

解决乱码问题

当在封装request请求的时候，读取中文时，会出现报错

java.nio.charset.MalformedInputException: Input length = 1

是因为字符编码的问题，在读取request输入流的时候指定字符集则可以解决。

BufferedReader br = new BufferedReader(new InputStreamReader(request.getInputStream(), StandardCharsets.UTF_8));