前言
很久之前写过一篇就是自动填充接口参数的，利用的 HandlerMethodArgumentResolver 自定义注解
Springboot Controller接口默认自动填充 业务实体参数值_springboot设置入参默认值-CSDN博客
现在这一篇也差不多，达到的目的就是重新去给post请求的参数赋值、修改啥的。
不多说，开始。
正文
首先知道一点，post请求的参数，一旦取出来就没了，因为是流数据。
所以老样子，我们写多一个HttpServletRequestWrapper ：
BodyReaderHttpServletRequestWrapper
import org.apache.commons.lang3.StringUtils;
import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.util.Enumeration;
import java.util.Map;
import java.util.Vector;/*** @Author : JCccc* @CreateTime : 2020/3/27* @Description :**/
public class BodyReaderHttpServletRequestWrapper extends HttpServletRequestWrapper {private final byte[] body;/*** 所有参数的集合*/private Map<String, String[]> parameterMap;public BodyReaderHttpServletRequestWrapper(HttpServletRequest request) throws IOException {super(request);BufferedReader reader = request.getReader();body = readBytes(reader);parameterMap = request.getParameterMap();}@Overridepublic BufferedReader getReader() throws IOException {ServletInputStream inputStream = getInputStream();if (null == inputStream) {return null;}return new BufferedReader(new InputStreamReader(inputStream));}@Overridepublic Enumeration<String> getParameterNames() {Vector<String> vector = new Vector<>(parameterMap.keySet());return vector.elements();}@Overridepublic ServletInputStream getInputStream() throws IOException {if (body == null) {return null;}final ByteArrayInputStream bais = new ByteArrayInputStream(body);return new ServletInputStream() {@Overridepublic boolean isFinished() {return false;}@Overridepublic boolean isReady() {return false;}@Overridepublic void setReadListener(ReadListener listener) {}@Overridepublic int read() throws IOException {return bais.read();}};}/*** 通过BufferedReader和字符编码集转换成byte数组** @param br* @return* @throws IOException*/private byte[] readBytes(BufferedReader br) throws IOException {String str;StringBuilder retStr = new StringBuilder();while ((str = br.readLine()) != null) {retStr.append(str);}if (StringUtils.isNotBlank(retStr.toString())) {return retStr.toString().getBytes(StandardCharsets.UTF_8);}return null;}
}然后是我们这一期的核心，
DefaultDataFillHandlerMethodArgumentResolver
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.speediance.admin.auth.ShiroUtils;
import com.speediance.admin.dto.req.UserDefaultDataFill;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeanWrapperImpl;
import org.springframework.core.MethodParameter;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;import javax.servlet.http.HttpServletRequest;
import java.io.BufferedReader;
import java.util.Date;
import java.util.Objects;@Component
public class DefaultDataFillHandlerMethodArgumentResolver implements HandlerMethodArgumentResolver {@Overridepublic boolean supportsParameter(MethodParameter parameter) {return parameter.hasParameterAnnotation(UserDefaultDataFill.class);}@Overridepublic Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {HttpServletRequest request = webRequest.getNativeRequest( HttpServletRequest.class );BodyReaderHttpServletRequestWrapper myRequestWrapper = new BodyReaderHttpServletRequestWrapper((HttpServletRequest) request);// 从Request的包装类中读取数据BufferedReader reader = myRequestWrapper.getReader();StringBuilder sb = new StringBuilder();String line;while ((line = reader.readLine()) != null) {sb.append(line);}reader.close();JSONObject jsonObject = JSON.parseObject(sb.toString());Object bean = BeanUtils.instantiateClass(parameter.getParameterType());BeanWrapper beanWrapper = new BeanWrapperImpl(bean);//重新赋值for (String key : jsonObject.keySet()) {beanWrapper.setPropertyValue(key,jsonObject.get(key));}Long userId = //比如从数据库查出来 或者从token解析出来;//举例子给如入参自动填充 更新操作人beanWrapper.setPropertyValue("updateUserId", userId);return bean;}}然后就是重写一个自定义注解 ，相当于需要填充数据或者进入到参数修改，我们采用它标注：
UserDefaultDataFill
import java.lang.annotation.*;@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface UserDefaultDataFill {}然后就OK了，看看怎么用：
比如说一个更新接口，我们想默认填充上入参里面的 修改用户ID （简单举例，其余业务要修改值，赋值自己套用就可以）
然后可以看到我们的参数解析器里面的代码 (其实就是复制流拿出参数，修改完变成当前接口的bean)：
OK，就到这。