引入包：
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.4.2</version>
</dependency>
public String callBack_wx(HttpServletRequest request) throws IOException {
}
原文：https://www.cnblogs.com/qk523/p/12659581.html