Question

我使用Neo4j 1.9.4进行项目，我遇到了一个奇怪的行为：

我有一段效果很好的代码。我已经用常春藤文件设置了类路径，一切正常。

public static void main(String[] args) {
    // the cache providers
    ArrayList<CacheProvider> cacheList = new ArrayList<CacheProvider>();
    System.out.println("Creating db configuration");
    cacheList.add(new SoftCacheProvider());

    // the kernel extensions
    LuceneKernelExtensionFactory lucene = new LuceneKernelExtensionFactory();
    List<KernelExtensionFactory<?>> extensions = new 
        ArrayList<KernelExtensionFactory<?>>();
    extensions.add(lucene);

    // the database setup
    GraphDatabaseFactory gdbf = new GraphDatabaseFactory();
    gdbf.setKernelExtensions(extensions);
    gdbf.setCacheProviders(cacheList);
    GraphDatabaseService db = gdbf.newEmbeddedDatabase("/tmp/test");
}

问题是当我尝试将cacheList.add(new SoftCacheProvider())更改为cacheList.add(new WeakCacheProvider())时出现以下错误：

java.lang.IllegalArgumentException: No provider for cache type 'soft'. Cache providers are loaded using java service loading where they register themselves in resource (plain-text) files found on the class path under META-INF/services/org.neo4j.kernel.impl.cache.CacheProvider. This missing provider may have been caused by either such a missing registration, or by the lack of the provider class itself.
    at org.neo4j.kernel.InternalAbstractGraphDatabase.create(InternalAbstractGraphDatabase.java:356)
    at org.neo4j.kernel.InternalAbstractGraphDatabase.run(InternalAbstractGraphDatabase.java:252)
    at org.neo4j.kernel.EmbeddedGraphDatabase.<init>(EmbeddedGraphDatabase.java:106)
    at org.neo4j.graphdb.factory.GraphDatabaseFactory$1.newDatabase(GraphDatabaseFactory.java:88)
    at org.neo4j.graphdb.factory.GraphDatabaseBuilder.newGraphDatabase(GraphDatabaseBuilder.java:207)
    at org.neo4j.graphdb.factory.GraphDatabaseFactory.newEmbeddedDatabase(GraphDatabaseFactory.java:69)
    at ttt.App.main(App.java:34)

如果我尝试使用NoChacheProvider或StrongCacheProvider，也会出现同样的错误。

我尝试使用以下内容添加文件META-INF/services/org.neo4j.kernel.impl.cache.CacheProvider，但它不会改变任何内容。

org.neo4j.kernel.impl.cache.WeakCacheProvider
org.neo4j.kernel.impl.cache.SoftCacheProvider
org.neo4j.kernel.impl.cache.NoCacheProvider
org.neo4j.kernel.impl.cache.StrongCacheProvider

你知道发生了什么吗？我不明白为什么只有一种缓存提供程序类型正在运行。

请注意，我必须使用Neo4j 1.9.4并且我无法更改它。

编辑：我的项目是一个基本的eclipse插件项目，没有任何其他依赖

Edit2：另一个有趣的一点是，如果我尝试使用Map<String,String>配置数据库，即使是<"cache_type","soft">，我也会遇到同样的错误。

public static void main(String[] args) {
    Map<String,String> config = new HashMap<String,String>();
    config.put("cache_type", "soft");
    GraphDatabaseService db = null;
    db = new EmbeddedGraphDatabase("/tmp/test", config, Collections.EMPTY_LIST, Collections.EMPTY_LIST, Collections.EMPTY_LIST, Collections.EMPTY_LIST);
}

java.lang.IllegalArgumentException: No provider for cache type 'soft'. Cache providers are loaded using java service loading where they register themselves in resource (plain-text) files found on the class path under META-INF/services/org.neo4j.kernel.impl.cache.CacheProvider. This missing provider may have been caused by either such a missing registration, or by the lack of the provider class itself.
    at org.neo4j.kernel.InternalAbstractGraphDatabase.create(InternalAbstractGraphDatabase.java:356)
    at org.neo4j.kernel.InternalAbstractGraphDatabase.run(InternalAbstractGraphDatabase.java:252)
    at org.neo4j.kernel.EmbeddedGraphDatabase.<init>(EmbeddedGraphDatabase.java:106)
    at ttt.App.main(App.java:36)

Answer 1

尝试直接在配置中指定它，如下所示：

GraphDatabaseService db = gdbf.newEmbeddedDatabaseBuilder('path/to/db').setConfig(GraphDatabaseSettings.cache_type, WeakCacheProvider.NAME).newGraphDatabase()

当然，我没有在1.9.4中试过这个，但是，也许值得一试。

设置Neo4j缓存

1 个答案: