解决 request.getInputStream()只能获取一次的问题

在开发中有时候我们会在filter中获取上传文件然后验证其合法性，但是在filter中获取一次以后，我们在controller想再次获取上传文件对象是获取不到的。request.getInputStream()返回的是ServletInputStream，此方法没有实现流的mark/reset方法，我们在filter中读取以后无法对流进行复位。实现方法，直接贴代码了。

BodyReaderHttpServletRequestWrapper.java

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 BodyReaderHttpServletRequestWrapper extends HttpServletRequestWrapper {
    private byte[] body;

    public BodyReaderHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
        super(request);
        try {
            body = StreamUtils.getByteByStream(request.getInputStream());
        } catch (Exception 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();
            }
        };
    }
}

StreamUtils.java

import java.io.ByteArrayOutputStream;
import java.io.InputStream;
public class StreamUtils {
    public static byte[] getByteByStream(InputStream is) throws Exception {
        byte[] buffer=new byte[1024];  
        int len=0;  
        ByteArrayOutputStream bos=new ByteArrayOutputStream();  
        while((len=is.read(buffer))!=-1){  
            bos.write(buffer,0,len);  
        }  
        bos.flush();  
        return bos.toByteArray();  
    }
}

UploadFilter.java

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
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;

public class UploadFilter implements Filter {

    public void destroy() {
        // TODO Auto-generated method stub

    }

    public void doFilter(ServletRequest arg0, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        // TODO Auto-generated method stub
        HttpServletRequest request = (HttpServletRequest) arg0;
        ServletRequest requestWrapper = new BodyReaderHttpServletRequestWrapper(request);
        //测试在filter中获取一次
        InputStream is = requestWrapper.getInputStream();
        // 读取要下载的文件，保存到文件输入流
        // 创建输出流
        String tempFileName = "C:/tempFile.jpg";
        // 指向临时文件
        File tempFile = new File(tempFileName);
        // outPutStream输出流指向临时文件
        FileOutputStream out = new FileOutputStream(tempFile);
        // 创建缓冲区
        byte buffer[] = new byte[1024];
        int len = 0;
        // 循环将输入流中的内容读取到缓冲区当中
        while ((len = is.read(buffer)) > 0) {
            // 输出缓冲区的内容到浏览器，实现文件下载
            out.write(buffer, 0, len);
        }
        // 关闭文件输入流
        is.close();
        // 关闭输出流
        out.close();

        chain.doFilter(requestWrapper, response);
    }

    public void init(FilterConfig arg0) throws ServletException {

    }

}

controller里面的方法

/**
     * 下载SQL文件
     * @param request
     * @param model
     */
    @RequestMapping(value="/downloadsql",method=RequestMethod.POST)
    public void downloadsql(HttpServletRequest request, HttpServletResponse response,Model model){

        //测试
        try {
            InputStream is = request.getInputStream();
            // 读取要下载的文件，保存到文件输入流
            // 创建输出流
            String tempFileName = "C:/tempFile.jpg";
            // 指向临时文件
            File tempFile = new File(tempFileName);
            // outPutStream输出流指向临时文件
            FileOutputStream out = new FileOutputStream(tempFile);
            // 创建缓冲区
            byte buffer[] = new byte[1024];
            int len = 0;
            // 循环将输入流中的内容读取到缓冲区当中
            while ((len = is.read(buffer)) > 0) {
                // 输出缓冲区的内容到浏览器，实现文件下载
                out.write(buffer, 0, len);
            }
            // 关闭文件输入流
            is.close();
            // 关闭输出流
            out.close();
        } catch (Exception e) {
            // TODO: handle exception
        }

        DiskFileItemFactory factory = new DiskFileItemFactory();  
        ServletFileUpload upload = new ServletFileUpload(factory);
        upload.setHeaderEncoding("UTF-8");
        if(!ServletFileUpload.isMultipartContent(request)){  
            return;
        }
        try {
            List<FileItem> list = upload.parseRequest(request);
            for(FileItem item : list){  
                if(!item.isFormField()){  
                    InputStream in = item.getInputStream();  
                    ExcelUtils eu = new ExcelUtils();
                    StringBuilder sb = new StringBuilder();
                    eu.readExcel(sb, in);
                    String sqlContent  = sb.toString();
                    FileManager fm = new FileManager();
                    Date date = new Date();
                    String path = request.getSession().getServletContext().getRealPath("/")+File.separator+"resources"+File.separator+"sql"+File.separator;
                    String fileName = "SQL"+TFun.getFormatDateYMDHMS(date)+".sql";
                    fm.createDirectory(path);
                    fm.createFile(path+fileName, sqlContent);
                    JSONObject result = new JSONObject();
                    result.put("success", true);
                    result.put("msg", "");
                    result.put("filepath", request.getContextPath()+File.separator+"resources"+File.separator+"sql"+File.separator+fileName);
                    //关闭输出流  
                    item.delete();
                    JSONService.writeStringIntoResponse(response, result.toJSONString());
                }
            }
        } catch (Exception e) {
            JSONObject result = new JSONObject();
            result.put("success", false);
            result.put("msg", e.getMessage());
            result.put("filepath", "");
            JSONService.writeStringIntoResponse(response, result.toJSONString());
            e.printStackTrace();
        }
    }