ServletRequest中读取body的数据

 InputStream body = request.getInputStream();

问题

• 数据流仅仅能够读取一次,如果你想要多次读取(在多个调用链中)(比如说在多个过滤器中),例如

    chain.doFilter(request, response);
  

这样后面的调用中request将读取不到body的数据.

解决

• 继承实现HttpServletRequest接口的HttpServletRequestWrapper,重载getInputStream方法.
• 

具体实现

BufferedServletRequestWrapper类

public class BufferedServletRequestWrapper extends HttpServletRequestWrapper {
    private byte[] buffer;
    public BufferedServletRequestWrapper(HttpServletRequest request) throws IOException {
        super(request);
        InputStream is = request.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte buff[] = new byte[ 1024 ];
        int read;
        while( ( read = is.read( buff ) ) > 0 ) {
            baos.write( buff, 0, read );
        }
        this.buffer = baos.toByteArray();
    }
    @Override
    public ServletInputStream getInputStream() throws IOException {
        return new BufferedServletInputStream( this.buffer );
    }
}

在过滤器中

ServletRequest requestWrapper = new BufferedServletRequestWrapper(req);
InputStream inputStream = requestWrapper.getInputStream();
String content = IOUtils.toString(inputStream, req
		.getCharacterEncoding());
/**对内容进行处理**/
chain.doFilter(requestWrapper, response);
/**由于我们在初始化时保存了byte,重载了getInputStream方法,所以后续调用时可以获得body中的数据**/