[JAVA] How to read Body of Request multiple times with Spring Boot + Spring Security

Introduction

In the Spring Security authorization process (voting class, etc.) I think there are cases where you have to refer to the Body of the Request. (For example, when updating the DB with POST or PUT, etc.

However, in the HttpServletRequest class Body is a stream and can only be read once.

So this time, I will introduce how to read Body multiple times.

Thing you want to do

① Hold the information read from Body (2) Replace the Body acquisition source with the information in (1)

Preparation of replacement class

Stream class Set as the return type when calling HttpServletRequest.getInputStream () Use byte array for initialization

BufferedServletInputStream.java

public class BufferedServletInputStream extends ServletInputStream {

	private ByteArrayInputStream inputStream;

	//Initialize with byte array
	public BufferedServletInputStream(byte[] buffer) {
		this.inputStream = new ByteArrayInputStream(buffer);
	}

	@Override
	public int available() throws IOException {
		return inputStream.available();
	}

	@Override
	public int read() throws IOException {
		return inputStream.read();
	}

	@Override
	public int read(byte[] b, int off, int len) throws IOException {
		return inputStream.read(b, off, len);
	}

	@Override
	public boolean isFinished() {
		return false;
	}

	@Override
	public boolean isReady() {
		return false;
	}

	@Override
	public void setReadListener(ReadListener listener) {

	}
}

Wrapper class for HttpServletRequest

BufferedServletRequestWrapper.java

public class BufferedServletRequestWrapper extends HttpServletRequestWrapper {

	private byte[] buffer;

	public BufferedServletRequestWrapper(HttpServletRequest request) throws IOException {
		super(request);

		//Get Stream from Request Body
		InputStream is = request.getInputStream();

		//Convert Stream to byte array and keep it in instance variable
		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();
	}

	//Replace the body acquisition source with this method
	@Override
	public ServletInputStream getInputStream() throws IOException {
		//Initialize Stream class and return
		return new BufferedServletInputStream(this.buffer);
	}
}

Actually replace

Filter class Replace by request by OncePerRequestFilter

MultipleReadEnableFilter.java

@Component
public class MultipleReadEnableFilter extends OncePerRequestFilter {

	@Override
	protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {

		//Initialize the wrapper class from HttpServletRequest
		HttpServletRequest wrappedRequest = new BufferedServletRequestWrapper((HttpServletRequest) request);
		filterChain.doFilter(wrappedRequest, response);
	}
}

Set the created Filter in the Spring Security setting class

//Wrap to read inputStream multiple times
http.addFilter(multipleReadEnableFilter);

reference

Yamaoku Tsushin Special Issue