整合SSM之springmvc 报错：No converter found for return value of type: class java.util.ArrayList

今天用idea整合SSM时测试报错

java.lang.IllegalArgumentException: No converter found for return value of type: class java.util.ArrayList
	org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:178)
	org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:153)
	org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:165)
	org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:80)
	org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:126)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:814)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:737)
	org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
	org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
	org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:969)
	org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:860)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
	org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:845)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

查阅了很多的博客资料，有说缺少getter、setter方法的，也有说缺少包的，然后我用的是阿里巴巴的依赖

   <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>fastjson</artifactId>
      <version>1.2.8</version>
  </dependency>

一直不行，然后后来没办法，换成jackson试了一下

<!--jackson，把对象和json格式互转换时需要用到 -->
      <dependency>
          <groupId>com.fasterxml.jackson.core</groupId>
          <artifactId>jackson-databind</artifactId>
          <version>2.9.7</version>
      </dependency>
      <dependency>
          <groupId>com.fasterxml.jackson.core</groupId>
          <artifactId>jackson-core</artifactId>
          <version>2.9.7</version>
      </dependency>

修改依赖后重新跑了一下

神奇的好了，这里记录一下，如果有同样错误的可以参考一下，亲测有效。