場景描述：

在 Spring Boot 自定義攔截器中，需要對請求 body 中的內容做簽名驗證。在日誌切面中，需要列印請求 body 中的內容。

報錯內容：

java.lang.IllegalStateException: getReader() has already been called for this request
 at org.apache.catalina.connector.Request.getInputStream(Request.java:1069)
 at org.apache.catalina.connector.RequestFacade.getInputStream(RequestFacade.java:
 
365)
 at com.igg.aggregate.server.aspect.LogAspect.before(LogAspect.java:80)

自己的報錯（想把getReader輸出兩遍）

java.lang.IllegalStateException: getReader() has already been called for this request
    org.apache.catalina.connector.Request.getInputStream(Request.java:1032)
    org.apache.catalina.connector.RequestFacade.getInputStream(RequestFacade.java:
 
364)
    org.apache.commons.fileupload.servlet.ServletRequestContext.getInputStream(ServletRequestContext.java:112)
    org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:952)
    org.apache.commons.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:
 
310)
    org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:334)
    org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:115)
    com.cc8w.controller.TestController.upload(TestController.java:68)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)

原因分析：

HttpServletRequest 的 getInputStream() 和 getReader() 都只能讀取一次，由於 Request Body 是流的形式讀取，那麼

流讀了一次就沒有了，所以只能被呼叫一次。

解決辦法：

先將 Request Body 儲存，然後通過 Servlet 自帶的 HttpServletRequestWrapper 類覆蓋 getReader() 和

getInputStream() 方法，使流從儲存的body讀取。然後再Filter中將ServletRequest替換為AuthenticationRequestWrapper。

程式碼示例：

public class MyRequestWrapper extends HttpServletRequestWrapper {
    private byte[] body;
 
    public MyRequestWrapper(HttpServletRequest request) throws IOException {
        super(request);
 
        StringBuilder sb = new StringBuilder();
        String line;
        BufferedReader reader = request.getReader();
        while ((line = reader.readLine()) != null) {
            sb.append(line);
        }
        String body = sb.toString();
        this.body = body.getBytes(StandardCharsets.UTF_8);
    }
 
 
    public String getBody() {
        return new String(body, StandardCharsets.UTF_8);
    }
}

// 獲取請求body
try {
     MyRequestWrapper myRequestWrapper = new MyRequestWrapper(request);
     return myRequestWrapper.getBody();
} catch (IOException e) {
     log.error("get request body exception", e);
     throw new RuntimeException(e);
}

轉 ：https://blog.csdn.net/magic_kid_2010/article/details/102782467