SpringBoot通过请求对象获取输入流无数据
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请求对象获取输入流无数据问题
昨天下午在开发的时候遇到了奇怪的事情，在SpringBoot的Controller里面直接使用HttpServletRequest的getInputStream()方法的时候获得的输入流无数据，通过getContentLength()获得内容长度的时候又是有值的，由于昨天比较晚了就没有研究，今天花了点时间查一下原因。
出现这种情况，首先怀疑输入流已经被使用了，由于请求输入流是不带缓存的，使用一次后流就无效了，通常触发解析输入流就是调用了getParameter()等方法，经过检查代码确认没有做过相关处理，所以怀疑SpringBoot底层做了处理。
查了一下SpringBoot的自动装配配置，在WebMvcAutoConfiguration中初始化了一个OrderedHiddenHttpMethodFilter，默认这个过滤器是生效的，相关代码如下：
@Bean
@ConditionalOnMissingBean(HiddenHttpMethodFilter.class)
@ConditionalOnProperty(prefix = "spring.mvc.hiddenmethod.filter", name = "enabled", matchIfMissing = true)
public OrderedHiddenHttpMethodFilter hiddenHttpMethodFilter() {
return new OrderedHiddenHttpMethodFilter();
}OrderedHiddenHttpMethodFilter继承了OrderedHiddenHttpMethodFilter，而OrderedHiddenHttpMethodFilter又继承了HiddenHttpMethodFilter，在该类的doFilterInternal()方法中发现有对参数做处理，相关代码如下：
@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
HttpServletRequest requestToUse = request;
if ("POST".equals(request.getMethod()) &&
request.getAttribute(WebUtils.ERROR_EXCEPTION_ATTRIBUTE) == null) {
String paramValue = request.getParameter(this.methodParam);
if (StringUtils.hasLength(paramValue)) {
String method = paramValue.toUpperCase(Locale.ENGLISH);
if (ALLOWED_METHODS.contains(method)) {
requestToUse = new HttpMethodRequestWrapper(request, method);
}
}
}
filterChain.doFilter(requestToUse, response);
}至此就可以定位问题的所在了，找到了问题下面就来看看如何解决。
方案一：禁用默认的过滤器
SpringBoot在自动装配的时候注入了OrderedHiddenHttpMethodFilter，如果我们不需要该功能，在配置文件中显示的将其设置为false。配置如下：
spring.mvc.hiddenmethod.filter.enabled=false方案二：使用@RequestBody注解
在需要获取请求输入流的方法上添加字节数组的参数，并添加@RequestBody注解，示例代码如下：
@RequestMapping("
@Slf4j
public class RequestWrapper extends HttpServletRequestWrapper {
private final byte[] body;
public RequestWrapper(HttpServletRequest request) throws IOException {
super(request);
// 将body数据存储起来
String bodyStr = getBodyString(request);
body = bodyStr.getBytes(Charset.defaultCharset());
}
public String getBodyString(final ServletRequest request) {
try {
return inputStream2String(request.getInputStream());
} catch (IOException e) {
log.error("", e);
throw new RuntimeException(e);
}
}
public String getBodyString() {
final InputStream inputStream = new ByteArrayInputStream(body);
return inputStream2String(inputStream);
}
private String inputStream2String(InputStream inputStream) {
StringBuilder sb = new StringBuilder();
BufferedReader reader = null;
try {
reader = new BufferedReader(new InputStreamReader(inputStream, Charset.defaultCharset()));
String line;
while ((line = reader.readLine()) != null) {
sb.append(line);
}
} catch (IOException e) {
log.error("", e);
throw new RuntimeException(e);
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
log.error("", e);
}
}
}
return sb.toString();
}
@Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(getInputStream()));
}
@Override
public ServletInputStream getInputStream() throws IOException {
final ByteArrayInputStream inputStream = new ByteArrayInputStream(body);
return new ServletInputStream() {
@Override
public int read() throws IOException {
return inputStream.read();
}
@Override
public boolean isFinished() {
return false;
}
@Override
public boolean isReady() {
return false;
}
@Override
public void setReadListener(ReadListener readListener) {
}
};
}
}定义一个过滤器 Filter
@Slf4j
public class ReplaceStreamFilter implements Filter {
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
ServletRequest requestWrapper = new RequestWrapper((HttpServletRequest) request);
chain.doFilter(requestWrapper, response);
}
}创建过滤器配置类 FilterConfig
@Configuration
public class FilterConfig {
@Bean
public FilterRegistrationBean someFilterRegistration() {
FilterRegistrationBean registration = new FilterRegistrationBean();
registration.setFilter(replaceStreamFilter());
registration.addUrlPatterns("
@Bean(name = "replaceStreamFilter")
public Filter replaceStreamFilter() {
return new ReplaceStreamFilter();
}
}完成以上步骤即可在拦截器中读取request中的body数据
@Slf4j
@Component
public class APIInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception{
log.info("开始拦截请求");
if(isJson(request)){
String jsonParam = new RequestWrapper(request).getBodyString();
JSONObject params = JSONObject.parseObject(jsonParam);
......
return true;
}
return false;
}
protected void returnJson(ServletResponse response, JSONObject json){
PrintWriter writer = null;
response.setCharacterEncoding("UTF-8");
response.setContentType("application/json; charset=utf-8");
try {
writer = response.getWriter();
writer.print(json.toJSONString());
} catch (IOException e) {
log.error("response error",e);
} finally {
if (writer != null)
writer.close();
}
}
private boolean isJson(HttpServletRequest request) {
if (request.getContentType() != null) {
return request.getContentType().equals(MediaType.APPLICATION_JSON_VALUE) ||
request.getContentType().equals(MediaType.APPLICATION_JSON_UTF8_VALUE);
}
return false;
}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。
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