java - 调用 request.getReader() 后重置 HttpRequest

Question

有没有一种方法可以在 HttpRequest 上调用 getReader() 方法，然后“重置”请求以便其他调用 getReader() 不会抛出 java.lang.IllegalStateException?

Answer 1

就像其他人所说的那样，不，我认为没有办法重置请求。

在继续之前，我一直处于想要在 ServletFilter 中记录请求内容的相同情况。这是一个forum post这帮助我弄清楚了如何创建像 Stephen C 所说的那样的 HttpServletRequestWrapper。这将存储数据，以便您可以多次调用 getReader() 和 getInputStream()。

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;

import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class MyRequestWrapper extends HttpServletRequestWrapper {

    private HttpServletRequest original;
    private byte[] reqBytes;
    private boolean firstTime = true;

    public MyRequestWrapper(HttpServletRequest request) {
        super(request);
        original = request;
    }

    @Override
    public BufferedReader getReader() throws IOException{

        if(firstTime)
            firstTime();

        InputStreamReader isr = new InputStreamReader(new ByteArrayInputStream(reqBytes));
        return new BufferedReader(isr);
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {

        if(firstTime)
            firstTime();

        ServletInputStream sis = new ServletInputStream() {
            private int i;

            @Override
            public int read() throws IOException {
                byte b;
                if(reqBytes.length > i)
                    b = reqBytes[i++];
                else
                    b = -1;

                return b;
            }
        };

        return sis;
    }

    private void firstTime() throws IOException{
        firstTime = false;
        StringBuffer buffer = new StringBuffer();
        BufferedReader reader = original.getReader();
        String line;
        while((line = reader.readLine()) != null){
            buffer.append(line);
        }
        reqBytes = buffer.toString().getBytes();
    }
}