spring mvc not returning json content

完整异常：

"The resource identified by this request is only capable of generating responses with characteristics not acceptable according to the request "accept" headers ()."

1.缺少以下包，或版本过低

<dependency>    <groupId>com.fasterxml.jackson.core</groupId>    <artifactId>jackson-core</artifactId>    <version>2.7.4</version></dependency><dependency>    <groupId>com.fasterxml.jackson.core</groupId>    <artifactId>jackson-annotations</artifactId>    <version>2.7.4</version></dependency><dependency>    <groupId>com.fasterxml.jackson.core</groupId>    <artifactId>jackson-databind</artifactId>    <version>2.7.4</version></dependency>

2.mvc配置文件缺少注解：

<mvc:annotation-driven/>