Springboot上传文件，但是使用CommonsMultipartResolver解析 并 使用 Multipartfile接收到文件后发现文件变大，且文件打不开，文件损坏_multipartfile 上传文件损坏

Springboot上传文件，

使用 CommonsMultipartResolver 解析

使用 Multipartfile 接收到文件后发现文件变大，且文件打不开，文件损坏

这是因为使用了自定义 CustomHttpServletRequestWrapper 包装类继承了 HttpServletRequestWrapper ，获取request 并读取了inputstream把inputsream转为string。

而文件上传时，inpustream转为string，就会出现解析出错，文件损坏。

解决：克隆inputstream 并保存 byte[] ，读取时 byte[] 转换为 inputstream ，这样可以多次读取inputstream

下面是助手类，克隆inputstream 并保存 byte[]

 
 
import java.io.*;
 
public class FileUtils {
 
    //TODO 克隆Inputstream 转换为byte[]
    public static byte[] cloneInputStream(InputStream inputStream){
        try {
            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int len;
            while ((len = inputStream.read(buffer)) > -1){
                byteArrayOutputStream.write(buffer,0,len);
            }
            byteArrayOutputStream.flush();
            byteArrayOutputStream.close();
            inputStream.close();
            return byteArrayOutputStream.toByteArray();
        }catch (IOException e){
            e.printStackTrace();
        }
        return null;
    }
 
    //TODO 使用byte[] 获取 克隆Inputstream
    public static InputStream getInputStream(byte[] bytes){
        InputStream inputStreamNew = null;
        if(bytes != null){
            inputStreamNew = new ByteArrayInputStream(bytes);
        }
        return inputStreamNew;
    }
 
    //TODO 使用byte[] 获取 克隆Inputstream
    public static ByteArrayInputStream getByteArrayInputStream(byte[] bytes){
        ByteArrayInputStream inputStreamNew = null;
        if(bytes != null){
            inputStreamNew = new ByteArrayInputStream(bytes);
        }
        return inputStreamNew;
    }
}

 下面是自定义 CustomHttpServletRequestWrapper 包装类继承了 HttpServletRequestWrapper

 
 
import FileUtils;
 
import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;
 
public class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper {
 
    // 保存request body的数据
    private String body;
    // 保存body byte[]
    private byte[] bodyBytes;
 
 
 
 
    // 解析request的inputStream(即body)数据，转成字符串
    public CustomHttpServletRequestWrapper(HttpServletRequest request) {
        super(request);
        StringBuilder stringBuilder = new StringBuilder();
        BufferedReader bufferedReader = null;
        InputStream inputStream = null;
        try {
            inputStream = request.getInputStream();
            //TODO 克隆 inputstream 到 byte[]
            bodyBytes = FileUtils.cloneInputStream(inputStream);
            inputStream = FileUtils.getInputStream(bodyBytes);
 
            if (inputStream != null) {
                bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                char[] charBuffer = new char[128];
                int bytesRead = -1;
                while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
                    stringBuilder.append(charBuffer, 0, bytesRead);
                }
            } else {
                stringBuilder.append("");
            }
        } catch (IOException ex) {
        } finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (bufferedReader != null) {
                try {
                    bufferedReader.close();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        body = stringBuilder.toString();
    }
 
    @Override
    public ServletInputStream getInputStream() throws IOException {
        //TODO 使用 byte[] 转换为 getByteArrayInputStream , 这样文件上传时就不会出现文件损坏
        final ByteArrayInputStream byteArrayInputStream = FileUtils.getByteArrayInputStream(bodyBytes);  
        ServletInputStream servletInputStream = new ServletInputStream() {
            @Override
            public boolean isFinished() {
                return false;
            }
            @Override
            public boolean isReady() {
                return false;
            }
            @Override
            public void setReadListener(ReadListener readListener) {
            }
            @Override
            public int read() throws IOException {
                return byteArrayInputStream.read();
            }
        };
        return servletInputStream;
    }
 
 
    @Override
    public BufferedReader getReader() throws IOException {
        return new BufferedReader(new InputStreamReader(this.getInputStream()));
    }
    public String getBody() {
        return this.body;
    }
    // 赋值给body字段
    public void setBody(String body) {
        this.body = body;
    }
}