Java设计模式应用——桥接模式

性能管理系统中，数据产生后需要经过采集，汇聚，入库三个流程，用户才能查询使用。

采集可以是snmp采集，也可以是ems采集；汇聚可以使storm汇聚，也可以是spark汇聚；入库可以是hdfs入库，也可以是mppdb入库。

针对不同场景，我们可以灵活选择不同的采集，汇聚，入库方式。这种一个功能需要多种服务支持，每种服务又有不同类型的实现，使用桥接模式再适合不过。

（注：这里仅仅是桥接模式的例子，实际应用中，采集、汇聚、入库时异步执行的，他们之间通过消息通信）

桥接模式，顾名思义，就是把每种服务看做一座桥，我们可以根据实际场景选择不同的桥。

上述例子表示数据产生到可以使用之前需要经过三座桥：采集桥->汇聚桥->入库桥。每座桥可以选择不同的构造。

下面来看具体代码

1、 采集桥

package com.coshaho.learn.bridge.collect;

/**
 * 
 * CollectionService.java Create on 2017年6月1日 下午11:00:10    
 *    
 * 类功能说明:   采集服务
 *
 * Copyright: Copyright(c) 2013 
 * Company: COSHAHO
 * @Version 1.0
 * @Author coshaho
 */
public abstract class CollectionService 
{
    abstract void execute();
    public void run()
    {
        execute();
    }
}

2、 汇聚桥

package com.coshaho.learn.bridge.aggregate;

import com.coshaho.learn.bridge.collect.CollectionService;

/**
 * 
 * AggregationService.java Create on 2017年6月1日 下午11:00:23    
 *    
 * 类功能说明:   汇聚服务
 *
 * Copyright: Copyright(c) 2013 
 * Company: COSHAHO
 * @Version 1.0
 * @Author coshaho
 */
public abstract class AggregationService 
{
    public void run()
    {
        if(null != collectionService)
        {
            collectionService.run();
        }
        execute();
    }
    
    abstract void execute();
    CollectionService collectionService;
    public AggregationService(CollectionService collectionService)
    {
        this.collectionService = collectionService;
    }
}

3、 入库桥

package com.coshaho.learn.bridge.store;

import com.coshaho.learn.bridge.aggregate.AggregationService;

/**
 * 
 * StoreService.java Create on 2017年6月1日 下午11:08:57    
 *    
 * 类功能说明:   入库服务
 *
 * Copyright: Copyright(c) 2013 
 * Company: COSHAHO
 * @Version 1.0
 * @Author coshaho
 */
public abstract class StoreService 
{
    public void run()
    {
        if(null != aggregationService)
        {
            aggregationService.run();
        }
        execute();
    }
    
    abstract void execute();
    AggregationService aggregationService;
    public StoreService(AggregationService aggregationService)
    {
        this.aggregationService = aggregationService;
    }
}

4、 EMS采集桥

package com.coshaho.learn.bridge.collect;

public class EMSCollectionService extends CollectionService
{
    @Override
    void execute() 
    {
        System.out.println("EMS collection.");
    }
}

5、 SNMP采集桥

package com.coshaho.learn.bridge.collect;

public class SNMPCollectionService extends CollectionService
{
    @Override
    void execute() 
    {
        System.out.println("SNMP collection.");
    }
}

6、 Storm汇聚桥

package com.coshaho.learn.bridge.aggregate;

import com.coshaho.learn.bridge.collect.CollectionService;

public class StormAggregationService extends AggregationService
{
    public StormAggregationService(CollectionService collectionService) 
    {
        super(collectionService);
    }

    @Override
    void execute() 
    {
        System.out.println("Storm aggregation.");
    }
}

7、 Spark汇聚桥

package com.coshaho.learn.bridge.aggregate;

import com.coshaho.learn.bridge.collect.CollectionService;

public class SparkAggregationService extends AggregationService
{
    public SparkAggregationService(CollectionService collectionService) 
    {
        super(collectionService);
    }

    @Override
    void execute() 
    {
        System.out.println("Spark aggregation.");
    }
}

8、 MPPDB入库桥

package com.coshaho.learn.bridge.store;

import com.coshaho.learn.bridge.aggregate.AggregationService;

public class MPPDBStoreService extends StoreService
{
    public MPPDBStoreService(AggregationService aggregationService)
    {
        super(aggregationService);
    }

    @Override
    void execute() 
    {
        System.out.println("MPPDB store.");
    }
}

9、 HDFS入库桥

package com.coshaho.learn.bridge.store;

import com.coshaho.learn.bridge.aggregate.AggregationService;

public class HDFSStoreService extends StoreService
{
    public HDFSStoreService(AggregationService aggregationService) 
    {
        super(aggregationService);
    }

    @Override
    void execute() 
    {
        System.out.println("HDFS store.");
    }
}

10、 测试类

package com.coshaho.learn.bridge;

import com.coshaho.learn.bridge.aggregate.AggregationService;
import com.coshaho.learn.bridge.aggregate.StormAggregationService;
import com.coshaho.learn.bridge.collect.CollectionService;
import com.coshaho.learn.bridge.collect.SNMPCollectionService;
import com.coshaho.learn.bridge.store.HDFSStoreService;
import com.coshaho.learn.bridge.store.StoreService;

/**
 * 
 * BridgeTest.java Create on 2017年6月1日 下午10:59:43    
 *    
 * 类功能说明:   桥接模式测试
 *
 * Copyright: Copyright(c) 2013 
 * Company: COSHAHO
 * @Version 1.0
 * @Author coshaho
 */
public class BridgeTest 
{
    public static void main(String[] args)
    {
        CollectionService snmpService = new SNMPCollectionService();
        AggregationService stormService = new StormAggregationService(snmpService);
        StoreService hdfsService = new HDFSStoreService(stormService);
        hdfsService.run();
    }
}

11、 测试结果

SNMP collection.
Storm aggregation.
HDFS store.