我正在用spring集成将对象转换为json。

<int-jdbc:inbound-channel-adapter query="SELECT * FROM posts" row-mapper="postMapper"
                                      channel="dataInbound" data-source="dataSource">
        <int:poller fixed-rate="5000" />
    </int-jdbc:inbound-channel-adapter>

    <int:channel id="dataInbound" />

    <int:object-to-json-transformer input-channel="dataInbound" output-channel="printing"/>
    <int:service-activator id="printing" method="print"
                           input-channel="print" ref="eventActivator"/>
 <bean id="postMapper" class="com.example.domain.PostsMapper"/>

    <bean id="eventActivator" class="com.example.Dispatcher"/>
public class Posts {

    private String id;
    private String title;
    private String author;
   ...Constructor and setters/getters...
}

public class PostsMapper implements RowMapper<Posts> {

    public Posts mapRow(ResultSet rs, int rowNum) throws SQLException{
        String id = rs.getString("id");
        String title = rs.getString("title");
        String author = rs.getString("author");
        return new Posts(id, title, author);
    }
}

但如何将变压器打印到控制台 <int:service-activator> . 我试过了，但没用：

public void print(List<Posts> posts){
        for (Posts post: posts){
            System.out.print("\n*****" + post);
        }
    }

我遇到的错误：

Failed to convert from type [java.util.ArrayList<?>] to type [java.util.List<com.example.domain.Posts>] for value '[{id=1, title=test, author=me}]'; nested exception is org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.util.LinkedHashMap<?, ?>] to type [com.example.domain.Posts]
No converter found capable of converting from type [java.util.LinkedHashMap<?, ?>] to type [com.example.domain.Posts]
Problem invoking method: public void com.example.Dispatcher.print(java.util.List)

我的朋友怎么样 bean 打印到控制台应该是什么样子？