最近有一個需要從接口請求參數後，打印日誌，進行接口參數記錄。
這裏記錄一下處理過程中出現的問題。
首先想到的就是request.getParameter(String )方法，但是這個方法只能在get請求中取到參數，post是不行的，後來想到了使用流的方式，調用request.getInputStream()獲取流，然後從流中讀取參數，如下代碼所示：
String body = "";
StringBuilder stringBuilder = new StringBuilder();
BufferedReader bufferedReader = null;
InputStream inputStream = null;
try {
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) {
e.printStackTrace();
} finally {
if (inputStream != null) {
try {
inputStream.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
if (bufferedReader != null) {
try {
bufferedReader.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
}
body = stringBuilder.toString();
代碼中的body就是request中的參數，我這裏傳的是JSON數據：{"page": 1, "pageSize": 10}，那麼body就是：body = "{"page": 1, "pageSize": 10}"，一個JSON字符串。這樣是可以成功獲取到post請求的body，但是，經過過濾器後，參數經過@RequestBody註解賦值給controller中的方法的時候，卻拋出了一個這樣的異常：
org.springframework.http.converter.HttpMessageNotReadableException: Required request body is missing
在網上查找資料後發現，request的輸入流只能讀取一次，那麼這是爲什麼呢？下面是答案：
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()。
那麼有什麼辦法可以用戶解決呢？上面這篇博客中提到了解決方案，就是重寫HttpServletRequestWrapper把request保存下來，然後通過過濾器把保存下來的request再填充進去，這樣就可以多次讀取request了。步驟如下所示：
①寫一個類，繼承HttpServletRequestWrapper
import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;
public class RequestWrapper extends HttpServletRequestWrapper {
private final String body;
public RequestWrapper(HttpServletRequest request) {
super(request);
StringBuilder stringBuilder = new StringBuilder();
BufferedReader bufferedReader = null;
InputStream inputStream = null;
try {
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) {
} finally {
if (inputStream != null) {
try {
inputStream.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
if (bufferedReader != null) {
try {
bufferedReader.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
}
body = stringBuilder.toString();
}
@Override
public ServletInputStream getInputStream() throws IOException {
final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes());
ServletInputStream servletInputStream = new ServletInputStream() {
@Override
public boolean isFinished() {
return false;
}
@Override
public boolean isReady() {
return false;
}
@Override
public void setReadListener(ReadListener readListener) {
}
@Override
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過濾器Filter，用來把request傳遞下去
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.annotation.Order;
import org.springframework.web.filter.OncePerRequestFilter;
import com.cetc.common.utils.CommonUtils;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;
import java.util.Date;
import java.util.Map;
/**
* @program: springboot
* @description:
* @author: Sid
* @date: 2018-11-19 09:21
* @since: 1.0
**/
@Order(0)
/**
* 註冊過濾器
* */
@WebFilter(filterName = "RequestResponseLogFilter", urlPatterns = "/*")
public class RequestFilter extends OncePerRequestFilter {
private static final Logger logger = LoggerFactory.getLogger(RequestFilter.class);
@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
try {
RequestWrapper requestWrapper = new RequestWrapper(request);
String body = requestWrapper.getBody();
String parameterStr =
"接收到請求 時間:" + CommonUtils.DEFAULT_DTF.format(new Date()) + ". 地址:" + request.getRequestURI()
+ "request ContentType: " + request.getContentType() + ". 參數:" + body;
logger.debug(parameterStr);
filterChain.doFilter(requestWrapper, response);
} catch (Exception e) {
logger.error("權限判斷出錯", e);
}
}
}
③在啓動類中註冊過濾器
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.MultipartConfigFactory;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
@SpringBootApplication
@ServletComponentScan //註冊過濾器註解
@Configuration
public class WebApplication {
public static void main(String[] args) {
SpringApplication.run(WebApplication.class, args);
}
}
經測試，問題解決