Filter中获取请求体body后再次读取的问题

ゝ一纸荒年。 2022-01-12 07:11 310阅读 0赞

# Filter中获取请求体body后再次读取的问题 #

工作需要，要将请求和响应做一些处理,写一个filter拦截请求，拦截request中body内容后，字符流关闭，  
controller取到的请求体内容为空。  
从Request中获取输入流，InputStream只能被读取一次。  
解决方案：给request添加一个包装类BodyWrapper，继承HttpServletRequestWrapper，  
先从request中取输入流，读取流中的数据，然后重写getInputStream（）和getReader（）方法。  
chain.doFilter(requestWrapper, response);

import java.io.BufferedReader;  
import java.io.ByteArrayInputStream;  
import java.io.IOException;  
import java.io.InputStreamReader;  
import java.nio.charset.Charset;  
import java.util.Enumeration;  
import javax.servlet.ReadListener;  
import javax.servlet.ServletInputStream;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletRequestWrapper;  
import com.xera.fsafesso.HttpHelper;

public class BodyWrapper extends HttpServletRequestWrapper \{  
    private final byte\[\] body;

public BodyWrapper(HttpServletRequest request) throws IOException \{  
        super(request);  
        body = HttpHelper.getBodyString(request).getBytes(Charset.forName("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 arg0) \{  
            \}  
        \};  
    \}

@Override  
    public String getHeader(String name) \{  
        return super.getHeader(name);  
    \}

@Override  
    public Enumeration<String> getHeaderNames() \{  
        return super.getHeaderNames();  
    \}

@Override  
    public Enumeration<String> getHeaders(String name) \{  
        return super.getHeaders(name);  
    \}  
\}

import java.io.BufferedReader;  
import java.io.IOException;  
import java.io.InputStream;  
import java.io.InputStreamReader;  
import java.nio.charset.Charset;  
import javax.servlet.ServletRequest;

public class HttpHelper \{  
     /\*\*  
     \* 获取请求Body  
     \* @param request  
     \* @return  
     \*/  
    public static String getBodyString(ServletRequest request) \{  
        StringBuilder sb = new StringBuilder();  
        InputStream inputStream = null;  
        BufferedReader reader = null;  
        try \{  
            inputStream = request.getInputStream();  
            reader = new BufferedReader(new InputStreamReader(inputStream, Charset.forName("UTF-8")));  
            String line = "";  
            while ((line = reader.readLine()) != null) \{  
                sb.append(line);  
            \}  
        \} catch (IOException e) \{  
            e.printStackTrace();  
        \} finally \{  
            if (inputStream != null) \{  
                try \{  
                    inputStream.close();  
                \} catch (IOException e) \{  
                    e.printStackTrace();  
                \}  
            \}  
            if (reader != null) \{  
                try \{  
                    reader.close();  
                \} catch (IOException e) \{  
                    e.printStackTrace();  
                \}  
            \}  
        \}  
        return sb.toString();  
    \}  
\}

Filter中写法如下：

HttpServletRequest httpServletRequest = (HttpServletRequest) request;  
            Map<String, String> requestMap = this.getTypesafeRequestMap(httpServletRequest);  
            requestWrapper = new BodyWrapper(httpServletRequest);  
            String body = HttpHelper.getBodyString(requestWrapper);  
            log.info("loggingFilter---请求路径 \{\},请求参数 \{\},请求体内容 \{\}",httpServletRequest.getRequestURL(),requestMap,body);

chain.doFilter(requestWrapper, response);

在使用注解的方式（即@WebFilter）声明过滤器时，

**需要再main函数类上添加@ServletComponentScan（basePackages = "此处写明类地址，格式为包名+类名（如com.\*）**