在Controller裏面 request獲取body 的Json讀取不到數據!!!!那就是RequestBody是流的形式讀取的,流讀取一次就沒有了!
爲什麼使用RequestBody只能讀取一遍請求數據流?
那是因爲流對應的是數據,數據放在內存中,有的是部分放在內存中。read 一次標記一次當前位置(mark position),第二次read就從標記位置繼續讀(從內存中copy)數據。 所以這就是爲什麼讀了一次第二次是空了。 怎麼讓它不爲空呢?只要inputstream 中的pos 變成0就可以重寫讀取當前內存中的數據。javaAPI中有一個方法public void reset() 這個方法就是可以重置pos爲起始位置,但是不是所有的IO讀取流都可以調用該方法!ServletInputStream是不能調用reset方法,這就導致了只能調用一次getInputStream()。
解決辦法:重寫HttpServletRequestWrapper方法
這種方法就是通過重寫HttpServletRequestWrapper把request的保存下來,然後通過過濾器保存下來的request在填充進去,這樣就可以多次讀取request了
1.重寫HttpServletRequestWrapper方法
public class RequestWrapper extends HttpServletRequestWrapper {
private final String body;
public RequestWrapper(HttpServletRequest request) throws IOException {
super(request);
StringBuilder stringBuilder = new StringBuilder();
BufferedReader bufferedReader = null;
try {
InputStream inputStream = request.getInputStream();
if (inputStream != null) {
bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
char[] charBuffer = new char[128];
int bytesRead = -1;
while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
stringBuilder.append(charBuffer, 0, bytesRead);
}
} else {
stringBuilder.append("");
}
} catch (IOException ex) {
throw ex;
} finally {
if (bufferedReader != null) {
try {
bufferedReader.close();
} catch (IOException ex) {
throw ex;
}
}
}
body = stringBuilder.toString();
}
@Override
public ServletInputStream getInputStream() throws IOException {
final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes());
ServletInputStream servletInputStream = new ServletInputStream() {
public boolean isFinished() {
return false;
}
public boolean isReady() {
return false;
}
public void setReadListener(ReadListener readListener) {}
public int read() throws IOException {
return byteArrayInputStream.read();
}
};
return servletInputStream;
}
@Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(this.getInputStream()));
}
public String getBody() {
return this.body;
}
}
2.攔截器CommonInterceptor
public class CommonInterceptor extends HandlerInterceptorAdapter {
private final Log log = LogFactory.getLog(CommonInterceptor.class);
public CommonInterceptor() {
}
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
RequestWrapper myRequestWrapper = new RequestWrapper((HttpServletRequest) request);
String body = myRequestWrapper.getBody();
System.out.println("我是攔截器:"+body);
// do something
return true;
}
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
super.postHandle(request, response, handler, modelAndView);
}
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
super.afterCompletion(request, response, handler, ex);
}
public void afterConcurrentHandlingStarted(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
super.afterConcurrentHandlingStarted(request, response, handler);
}
}
3.在spring-mvc.xml聲明springMVC的攔截器
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<bean class="com.sdut.platform.core.CommonInterceptor"/>
</mvc:interceptor>
</mvc:interceptors>
4.過濾器HttpServletFilter類
public class HttpServletFilter implements Filter {
public void init(FilterConfig filterConfig) throws ServletException {
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
ServletRequest requestWrapper = null;
System.out.println("我是過濾器");
if(request instanceof HttpServletRequest) {
requestWrapper = new RequestWrapper((HttpServletRequest) request);
}
if(requestWrapper == null) {
chain.doFilter(request, response);
} else {
chain.doFilter(requestWrapper, response);
}
}
public void destroy() {
}
}
5.在web.xml中註冊過濾器
<filter>
<filter-name>requestFilter</filter-name>
<filter-class>com.sdut.platform.core.HttpServletFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>requestFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
經過測試完全可以並且不出現其他錯誤。