配置RepeatableFilter

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;
    }

}