引入其餘類定義的靜態變量

1. 引入方式

　　import  static  類路徑.*;

2. 示例

2.1 須要被導入的類

package com.streamax.s17.mcs.business.message;import javax.annotation.Resource;
import java.util.Date;
import java.util.Map;

/**
 * @Describe:
 * @Author: chenfan
 * @Date: 2019/4/29 13:26
 */
@Slf4j
@Component
public class MqttMessageListener implements IMqttMessageListener {

    public static final String TRANSFER_BEGIN = "s17/media/handout/op_session_client_pull_begin";
    public static final String TRANSFER_END = "s17/media/handout/op_session_client_pull_end";
    public static final String TRANSFER_CONTROL = "s17/media/op_session_control";
}

2.2 須要導入的類

package com.streamax.s17.mcs.business.message;

import lombok.extern.slf4j.Slf4j;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import static com.streamax.s17.mcs.business.message.MqttMessageListener.*; /**
 * @Describe:
 * @Author: chenfan
 * @Date: 2019/4/26 15:17
 */
@Slf4j
@Component
public class MessageHandler {

    private MqttMessageListener listener;

    private MqttClient mqttClient;

    public static final String filter = "/#";

    @Autowired
    public MessageHandler(MqttClient mqttClient,MqttMessageListener listener ) {
        this.mqttClient = mqttClient;
        this.listener = listener;
        init();
    }

    /**
     * 訂閱關心事件
     */
    public void init(){
        try {
　　　　　　　// 導入後便可經過變量名直接使用，不須要經過類名引用變量
            mqttClient.subscribe(TRANSFER_BEGIN + filter, 1, listener);
            mqttClient.subscribe(TRANSFER_END + filter, 1, listener);
            mqttClient.subscribe(TRANSFER_CONTROL + filter, 1, listener);
            log.info("subscribe topics success");
        } catch (MqttException e) {
            log.error("subscribe topics occur a exception:{ }",e);
        }
    }

}