欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页

解决 request.getInputStream()只能获取一次的问题

程序员文章站 2022-03-10 12:09:36
...

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();
        }
    }