No converter found for return value of type: class java.util.ArrayList（json数据转换错误）

1.在pom.xml添加依赖

<!-- jackson -->
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.8.5</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.8.5</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-annotations</artifactId>
        <version>2.8.5</version>
    </dependency>

2.在springmvc中添加配置

<mvc:annotation-driven>
	    <mvc:message-converters>
	        <bean class="org.springframework.http.converter.StringHttpMessageConverter"/>
	        <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/>
	    </mvc:message-converters>
	</mvc:annotation-driven>