SpringBoot v2.2以上重复读取Request Body内容
一、需求
项目有两个场景会用到从Request的Body中读取内容。
- 打印请求日志
- 提供Api接口，在api方法执行前，从Request Body中读取参数进行验签，验签通过后在执行api方法
二、解决方案
2.1 自定义RequestWrapper
public class MyRequestWrapper extends HttpServletRequestWrapper {
private final String body;
public MyRequestWrapper(HttpServletRequest request) throws IOException {
super(request);
this.body = RequestReadUtils.read(request);
}
public String getBody() {
return body;
}
@Override
public ServletInputStream getInputStream() throws IOException {
final ByteArrayInputStream bais = new ByteArrayInputStream(body.getBytes());
return new ServletInputStream() {
...略
};
}
@Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(this.getInputStream()));
}
}
RequestReadUtils（网上抄的）
private static final int BUFFER_SIZE = 1024 * 8;
public static String read(HttpServletRequest request) throws IOException {
BufferedReader bufferedReader = request.getReader();
for (Enumeration<String> iterator = request.getHeaderNames(); iterator.hasMoreElements();) {
String type = iterator.nextElement();
System.out.println(type+" = "+request.getHeader(type));
}
System.out.println();
StringWriter writer = new StringWriter();
write(bufferedReader,writer);
return writer.getBuffer().toString();
}
public static long write(Reader reader,Writer writer) throws IOException {
return write(reader, writer, BUFFER_SIZE);
}
public static long write(Reader reader, Writer writer, int bufferSize) throws IOException
{
int read;
long total = 0;
char[] buf = new char[bufferSize];
while( ( read = reader.read(buf) ) != -1 ) {
writer.write(buf, 0, read);
total += read;
}
return total;
}2.2 定义Filter
@WebFilter
public class TestFilter implements Filter{
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain){
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;
MyRequestWrapper wrapper = WebUtils.getNativeRequest(request, MyRequestWrapper.class);
chain.doFilter(wrapper == null ? new MyRequestWrapper(request) :wrapper,servletRequest);
}
}三、遇到问题
使用的SpringBoot v2.1.x版本
- Form提交无问题
- 获取RequestBody无问题
使用SpringBoot v2.2.0以上版本（包括v2.3.x）
- Form提交无法获取参数
- 获取RequestBody无问题
四、问题排查
经过排查，v2.2.x对比v2.1.x的不同在于一下代码差异：
BufferedReader bufferedReader = request.getReader();
-----------------
char[] buf = new char[bufferSize];
while( ( read = reader.read(buf) ) != -1 ) {
writer.write(buf, 0, read);
total += read;
}当表单提交时
- v2.1.x无法read到内容，读取结果为-1
- v2.2.x、v2.3.x能够读取到内容
当表单提交时（x-www-form-urlencoded），inputStream读取一次后后续不会触发wrapper的getInputStream操作，所以Controller无法获取到参数。
解决方案
MyRequestWrapper改造
public class MyRequestWrapper extends HttpServletRequestWrapper {
private final String body;
public MyRequestWrapper(HttpServletRequest request) throws IOException {
super(request);
this.body = getBodyString(request);
}
public String getBody() {
return body;
}
public String getBodyString(final HttpServletRequest request) throws IOException {
String contentType = request.getContentType();
String bodyString = "";
StringBuilder sb = new StringBuilder();
if (StringUtils.isNotBlank(contentType) && (contentType.contains("multipart/form-data") || contentType.contains("x-www-form-urlencoded"))) {
Map<String, String[]> parameterMap = request.getParameterMap();
for (Map.Entry<String, String[]> next : parameterMap.entrySet()) {
String[] values = next.getValue();
String value = null;
if (values != null) {
if (values.length == 1) {
value = values[0];
} else {
value = Arrays.toString(values);
}
}
sb.append(next.getKey()).append("=").append(value).append("&");
}
if (sb.length() > 0) {
bodyString = sb.toString().substring(0, sb.toString().length() - 1);
}
return bodyString;
} else {
return IOUtils.toString(request.getInputStream());
}
}
@Override
public ServletInputStream getInputStream() throws IOException {
final ByteArrayInputStream bais = new ByteArrayInputStream(body.getBytes());
return new ServletInputStream() {
@Override
public boolean isFinished() {
return false;
}
@Override
public boolean isReady() {
return false;
}
@Override
public int read() {
return bais.read();
}
@Override
public void setReadListener(ReadListener readListener) {
}
};
}
@Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(this.getInputStream()));
}
}
SpringBoot 读取Request参数的坑
后端拿参数相关
默认配置时，
getInputStream()和getReader()一起使用会报错
使用两遍getInputStream()，第二遍会为空
当存在@RequestBody等注解时，springMVC已读取过一遍流，默认单独使用getInputStream()或getReader()都为空。
解决：写filter继承HttpServletRequestWrapper，缓存InputStream，覆盖getInputStream()和getReader()方法，使用ByteArrayInputStream is = new ByteArrayInputStream(body.getBytes());读取InputStream。
注意：springboot中，过滤器只需@Component即可生效，另外可在FilterRegistrationBean中配置路径和优先级。
对于拦截器，必须在InterceptorRegistry中调用addInterceptor方法。（路径可链式添加）
关于流
只能读一遍，类似管子。
只承担传输职责，而与处理和存储无关。
对于byte流而言，进行重复读取易于实现，但指针不重置，应是为了与InputStream接口定义保持一致。
以上为个人经验，希望能给大家一个参考，也希望大家多多支持编程网。
