捕获JSP输出,保存到文件

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class JspOutputFilter implements Filter {

    private String filePath;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        filePath = filterConfig.getInitParameter("filePath");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        CaptureOutputResponse captureResponse = new CaptureOutputResponse(response);
        chain.doFilter(request, captureResponse);
        String output = captureResponse.getOutput();
        try (PrintWriter writer = new PrintWriter(new FileWriter(new File(filePath)))) {
            writer.println(output);
        }
    }

    @Override
    public void destroy() {
    }

    private static class CaptureOutputResponse extends OutputStreamWriter {

        private StringBuilder output = new StringBuilder();

        public CaptureOutputResponse(ServletResponse response) throws IOException {
            super(response.getOutputStream());
        }

        @Override
        public void write(char[] cbuf, int off, int len) throws IOException {
            output.append(cbuf, off, len);
            super.write(cbuf, off, len);
        }

        public String getOutput() {
            return output.toString();
        }
    }
}