spring mvc not returning json content - error 406

完整異常：

"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，或版本過低

<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配置文件缺少註解：

<mvc:annotation-driven/>