1.1．自定义Sink说明

sink是flume中用于指定数据下沉地的组件。自带的已经很多，对于某些sink如果没有我们想要的，也可以自定义sink实现将数据保存到我们想要的地方去，例如kafka，或者mysql，或者文件等等都可以

需求如下：从网络端口当中发送数据，自定义sink，使用sink从网络端口接收数据，然后将数据保存到本地文件当中去。

1.2．自定义Sink原理实现

自定义MySink

public class MySink extends AbstractSink implements Configurable {
    private Context context ;
    private String filePath = "";
    private String fileName = "";
    private File fileDir;

    //这个方法会在初始化调用，主要用于初始化我们的Context，获取我们的一些配置参数
    @Override
    public void configure(Context context) {
        try {
            this.context = context;
            filePath = context.getString("filePath");
            fileName = context.getString("fileName");
            fileDir = new File(filePath);
            if(!fileDir.exists()){
                fileDir.mkdirs();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    //这个方法会被反复调用
    @Override
    public Status process() throws EventDeliveryException {
        Event event = null;
        Channel channel = this.getChannel();
        Transaction transaction = channel.getTransaction();
        transaction.begin();
        while(true){
            event = channel.take();
            if(null != event){
                break;
            }
        }
        byte[] body = event.getBody();
        String line = new String(body);
        try {
            FileUtils.write(new File(filePath+File.separator+fileName),line,true);
            transaction.commit();
        } catch (IOException e) {
            transaction.rollback();
            e.printStackTrace();
            return Status.BACKOFF;
        }finally {
            transaction.close();
        }
        return Status.READY;
    }
}

1.3 功能测试

将代码使用打包插件，打成jar包，注意一定要将commons-langs这个依赖包打进去，放到flume的lib目录下
开发flume的配置文件：

a1.sources = r1
a1.sinks = k1
a1.channels = c1
# Describe/configure the source
a1.sources.r1.type = netcat
a1.sources.r1.bind = node-1
a1.sources.r1.port = 5678
a1.sources.r1.channels = c1
# # Describe the sink
a1.sinks.k1.type = cn.itcast.flumesink.MySink
a1.sinks.k1.filePath=/export/servers
a1.sinks.k1.fileName=filesink.txt
# # Use a channel which buffers events in memory
a1.channels.c1.type = memory
a1.channels.c1.capacity = 1000
a1.channels.c1.transactionCapacity = 100
# # Bind the source and sink to the channel
a1.sources.r1.channels = c1
a1.sinks.k1.channel = c1

1.4启动flume，并且使用telnet测试：

bin/flume-ng agent -c conf -f conf/filesink.conf -n a1 -Dflume.root.logger=INFO,console

Telnet node-1 5678 连接到机器端口上输入数据。