PHP Web服务返回数组，但无法从Java客户端获取数组

我写了一个php web服务。函数如下：

function get_device_info(){
    $conn= mysql_connect("localhost", "admin", "123456") or die("Could not connect: " . mysql_error());
    mysql_select_db('devices',$conn);
    $sql="select id,description,hostname,status_rec_date,availability from host";
    $query=mysql_query($sql);
    while($myrow = mysql_fetch_array($result)){
        $host_msg[$i]=$myrow;
        $i++;
    }
   return $host_msg;
   mysql_close($conn);
}

然后我用java编写了soap客户端来调用这个Web服务。

import java.net.MalformedURLException;  
import java.rmi.RemoteException;  
import javax.xml.rpc.ServiceException;  
import org.apache.axis.client.Call;  
import org.apache.axis.client.Service;
public class javasoapclient {
    public static void main(String[] args) throws ServiceException, MalformedURLException, RemoteException {  
        String serviceUrl = "http://192.168.1.44/webservices/serverSoap.php";  
        Service service = new Service();  
        Call call = (Call) service.createCall();  
        call.setTargetEndpointAddress(new java.net.URL(serviceUrl));  
        call.setOperationName("get_device_info");
        String reVal = call.invoke(new Object[] {}).toString();
        System.out.println(reVal);
    }
}

它无法获取数组。我是PHP的新手。谁能帮忙？

提前感谢！