apache-httpclient-4.x - HttpClient 不可序列化异常

Question

我正在尝试实现一个基本的 1 spout - 1 bolt Storm 拓扑。我有一个 Storm Bolt，可以使用 Apache HttpClient (4.3.1) 发出 HTTP 请求。但是，当我运行它时出现以下异常:

[main] ERROR org.apache.zookeeper.server.NIOServerCnxn  - Thread Thread[main,5,main] died
java.lang.RuntimeException: java.io.NotSerializableException: org.apache.http.impl.client.InternalHttpClient
    at backtype.storm.utils.Utils.serialize(Utils.java:56)
    at backtype.storm.topology.TopologyBuilder.createTopology(TopologyBuilder.java:89)
    at app.storm.StormTopology.main(StormTopology.java:26)
Caused by: java.io.NotSerializableException: org.apache.http.impl.client.InternalHttpClient
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1183)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1547)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1508)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1431)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1177)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:347)
    at backtype.storm.utils.Utils.serialize(Utils.java:52)
    ... 2 more 

还有人看过吗？我知道 Storm 本身在内部使用 HTTP Client (4.1.1)。我尝试用 4.3.1 版本替换内部库，但我又遇到了另一个错误:

Exception in thread "main" java.lang.NoSuchFieldError: INSTANCE
    at org.apache.http.impl.io.DefaultHttpRequestWriterFactory.<init>(DefaultHttpRequestWriterFactory.java:52)
    at org.apache.http.impl.io.DefaultHttpRequestWriterFactory.<init>(DefaultHttpRequestWriterFactory.java:56)
    at org.apache.http.impl.io.DefaultHttpRequestWriterFactory.<clinit>(DefaultHttpRequestWriterFactory.java:46)
    at org.apache.http.impl.conn.ManagedHttpClientConnectionFactory.<init>(ManagedHttpClientConnectionFactory.java:72)
    at org.apache.http.impl.conn.ManagedHttpClientConnectionFactory.<init>(ManagedHttpClientConnectionFactory.java:84)
    at org.apache.http.impl.conn.ManagedHttpClientConnectionFactory.<clinit>(ManagedHttpClientConnectionFactory.java:59)
    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager$InternalConnectionFactory.<init>(PoolingHttpClientConnectionManager.java:487)
    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.<init>(PoolingHttpClientConnectionManager.java:147)
    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.<init>(PoolingHttpClientConnectionManager.java:136)
    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.<init>(PoolingHttpClientConnectionManager.java:112)
    at org.apache.http.impl.client.HttpClientBuilder.build(HttpClientBuilder.java:727)
    at org.apache.http.impl.client.HttpClients.createDefault(HttpClients.java:58)
    at app.storm.bolts.DataFetcherBolt.<init>(DataFetcherBolt.java:34)
    at app.storm.StormTopology.main(StormTopology.java:18)

Answer 1

我从 Storm 项目的 Google 论坛得到了答案。这是该帖子的链接:

https://groups.google.com/forum/#!topic/storm-user/vdfamKeR9Lk

解决方法是在 Bolt 类的 prepare 方法中实例化 HttpClient 实例。