springboot 获取到的inputStream为空的问题

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springboot在接收http请求的时候读取的request的inputStream，造成我们想自己读取inputStream的时候发现inputStream已经无法读取了。

为了读取inputStream，我们应该在springboot读取之前把inputStream的内容暂存先来。

1 这里要使用一个类HttpServletRequestWrapper，我们写一个类继承这个类，把传入的request中的inputStream转为byte[] 暂存下来，重写其中的getInputStream方法，每次返回由暂存的byte转换而来的 inputStream。

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Collection;
import java.util.stream.Collectors;import javax.servlet.ReadListener;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.Part;import org.springframework.web.bind.annotation.RequestMethod;public class InputStreamHttpServletRequestWrapper extends HttpServletRequestWrapper {
private final byte[] streamBody;
private static final int BUFFER_SIZE = 4096; public InputStreamHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
super(request);
byte[] bytes = new byte[0];
String uri = request.getRequestURI();
if (Objects.isNull(request.getHeader("Content-Type")) || request.getHeader("Content-Type").contains("multipart/form-data;")) {
bytes = inputStream2Byte(request.getInputStream());
} else if (isFormPost(request)) {
// 从ParameterMap获取参数，并保存以便多次获取
bytes = params2Byte(request);
} else {
bytes = inputStream2Byte(request.getInputStream());
} streamBody = bytes;
// this.setRequest(this);
} private boolean isFormPost(HttpServletRequest request) {
return RequestMethod.POST.name().equals(request.getMethod());
} private byte[] params2Byte(HttpServletRequest request) {
byte[] bytes = request.getParameterMap().entrySet().stream().map(entry -> {
String result;
String[] value = entry.getValue();
if (value != null && value.length > 1) {
result = Arrays.stream(value).map(s -> entry.getKey() + "=" + s).collect(Collectors.joining("&"));
} else {
result = entry.getKey() + "=" + value[0];
} return result;
}).collect(Collectors.joining("&")).getBytes();
return bytes;
} private byte[] inputStream2Byte(InputStream inputStream) throws IOException {
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
byte[] bytes = new byte[BUFFER_SIZE];
int length;
while ((length = inputStream.read(bytes, 0, BUFFER_SIZE)) != -1) {
outputStream.write(bytes, 0, length);
} return outputStream.toByteArray();
} @Override
public ServletInputStream getInputStream() throws IOException {
ByteArrayInputStream inputStream = new ByteArrayInputStream(streamBody); return new ServletInputStream() {
@Override
public boolean isFinished() {
return false;
} @Override
public boolean isReady() {
return false;
} @Override
public void setReadListener(ReadListener listener) { } @Override
public int read() throws IOException {
return inputStream.read();
}
};
} @Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(getInputStream()));
}
}

2.这里要使用一个神奇的filter：HiddenHttpMethodFilter

在这个类中调用之前定义的 InputStreamHttpServletRequestWrapper类，并把实例化之后的类传入以后的filter中，这样以后所有的 ServletRequest 都是我们自己定义的了。

import java.io.IOException;import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.springframework.web.filter.HiddenHttpMethodFilter;
import org.springframework.web.filter.OncePerRequestFilter;import com.esri.rest.configure.helper.InputStreamHttpServletRequestWrapper;public class InputStreamWrapperFilter extends HiddenHttpMethodFilter { @Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException { ServletRequest servletRequest = new InputStreamHttpServletRequestWrapper(request); filterChain.doFilter(servletRequest, response); }}

3，最后一步：把filter加入springboot 配置

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;
import org.springframework.web.filter.HiddenHttpMethodFilter;import com.esri.rest.filter.InputStreamWrapperFilter;@Configuration
public class RequestConfig { @Bean
@Order(1)
public HiddenHttpMethodFilter hiddenHttpMethodFilter() {
return new InputStreamWrapperFilter();
}
}