（4）JanusGraph学习-----connect via JAVA

1.通过内嵌方式访问JG

通过前文了解到JG本身就是一堆jar包，没有执行线程。所以两种访问方式，一种是通过现在服务器上启动一个gremlin-server (第三节中的内容) 。一种就是jar包内嵌的客户系统中，也就是要放到一个main函数或者spring web容器中去执行jg的jar包。

这里主要通过调用JG的相关java依赖包，结合配置文件，通过JanusGraphFactory.open()来访问对应的图库。首先演示通过main或者单元测试来跑通JG连接。

为了大家更好的理解内嵌的方式，大家可以：首先kill第三节中gremlin-server服务进程,再删除数据。（hbase和ES索引）

首先参考官方给出的example，构建出如下的目录结构：

相关核心代码：

1.1GraphDB类

主要封装一些统一的方法。这里我们通过GraphFactory.open(conf)方法来打开图库。注意通过查看源码可以得知：配置文件中必须定义key：gremlin.graph。GraphFactory会调用对应的指定工厂类的open代码。考虑后期扩展性，所以这里不直接写死JanusGraphFactory.open()。

public class GraphDB {

    private static final Logger LOGGER = LoggerFactory.getLogger(GraphDB.class);

    protected String propFileName;

    protected Configuration conf;

    protected Graph graph;

    protected GraphTraversalSource g;

    protected boolean supportsTransactions;

    protected boolean supportsSchema;

    protected boolean supportsGeoshape;

    public GraphDB(final String fileName) {

        this.propFileName = fileName;

    }

    public GraphTraversalSource openGraph() throws ConfigurationException {

        LOGGER.info("[andlinks]: opening graph");

        conf = new PropertiesConfiguration(propFileName);

        graph = GraphFactory.open(conf);

        g = graph.traversal();

        return g;

    }

    public GraphTraversalSource createGraph()  {

        return null;

    }

    public void closeGraph() throws Exception {

        LOGGER.info("[andlinks]:closing graph");

        try {

            if (g != null) {

                g.close();

            }

            if (graph != null) {

                graph.close();

            }

        } finally {

            g = null;

            graph = null;

        }

    }

    **

     * Drops the graph instance. The default implementation does nothing.

     */

    public void dropGraph() throws Exception {

    }

    **

     * Creates the graph schema. The default implementation does nothing.

     */

    public void createSchema() {

    }

}

1.2 JanusGraphDB类

    继承GraphDB类，提供一系列图操作接口。

public class JanusGraphDB extends GraphDB{

    private static final Logger LOGGER= LoggerFactory.getLogger(JanusGraph.class);

    public JanusGraphDB(final String fileName) {

        super(fileName);

        this.supportsSchema = true;

        this.supportsTransactions = true;

        this.supportsGeoshape = true;

    }

    @Override

    public GraphTraversalSource openGraph() throws ConfigurationException {

        super.openGraph();

        return g;

    }

    @Override

    public GraphTraversalSource createGraph() {

        return super.createGraph();

    }

    @Override

    public void dropGraph() throws Exception {

        if (graph != null) {

            JanusGraphFactory.drop(getJanusGraph());

        }

    }

    protected JanusGraph getJanusGraph() {

        return (JanusGraph) graph;

    }

    @Override

    public void createSchema() {

        final JanusGraphManagement management = this.getJanusGraph().openManagement();

        try {

             naive check if the schema was previously created

//            if (management.getRelation*(RelationType.class).iterator().hasNext()) {

//                management.rollback();

//                return;

//            }

            LOGGER.info("[andlinks]:creating schema");

//            createProperties(management);

            createVertexLabels(management);

//            createEdgeLabels(management);

//            createCompositeIndexes(management);

//            createMixedIndexes(management);

            management.commit();

        } catch (Exception e) {

            management.rollback();

        }

    }

    **

     * Creates the vertex labels.

     */

    protected void createVertexLabels(final JanusGraphManagement management) {

        management.makeVertexLabel("titan").make();

        management.makeVertexLabel("location").make();

        management.makeVertexLabel("god").make();

        management.makeVertexLabel("demigod").make();

        management.makeVertexLabel("human").make();

        management.makeVertexLabel("monster").make();

    }

}

1.3 janusgraph-hbase-es.properties配置文件

这里没有配置graph.graphname的话，默认是janusgraph图库。对应的hbase表名和图库名一致。后期如果要做多图配置的话，需要设置该key。

gremlin.graph=org.janusgraph.core.JanusGraphFactory

#graph.graphname=cc

#graph.graphname=ConfigurationManagementGraph

# 存储后端配置

storage.backend=hbase

# your zookper hostname

storage.hostname=192.168.1.22

# mac os中：如果你想远程连接 还需要做的是 把hbase的host文件copy过来放到你的本机的hosts文件中

# 缓存配置

# cache.db-cache = true

# cache.db-cache-clean-wait = 20åå

# cache.db-cache-time = 180000

# cache.db-cache-size = 0.5

# es 配置

index.search.backend=elasticsearch

index.search.hostname=192.168.1.22

1.4 pom文件

一开始直接使用了janusgraph-all依赖包，内部包含了所有的JG依赖。类似于springboot。但是实际启动过程中会报各种class not found错误。查看依赖树发现是多个版本冲突导致。考虑多个jar冲突报错和后期第三方jar包的增加，这里单独引用需要用到的小依赖。需要注意下hbase-shaded-client和elasticsearch-rest-client的版本，试过几次才找到对应的可用版本。具体的报错信息见末尾的报错总结。

    <dependencies>

        <!--<dependency>-->

            <!--<groupId>org.janusgraph</groupId>-->

            <!--<artifactId>janusgraph-all</artifactId>-->

            <!--<version>${jg.version}</version>-->

        <!--</dependency>-->

        <dependency>

            <groupId>org.janusgraph</groupId>

            <artifactId>janusgraph-core</artifactId>

            <version>${jg.version}</version>

        </dependency>

        <!--<dependency>-->

            <!--<groupId>com.fasterxml.jackson.core</groupId>-->

            <!--<artifactId>jackson-core</artifactId>-->

            <!--<version>2.6.2</version>-->

        <!--</dependency>-->

        <!--<dependency>-->

            <!--<groupId>org.apache.httpcomponents</groupId>-->

            <!--<artifactId>httpcore</artifactId>-->

            <!--<version>4.2.3</version>-->

        <!--</dependency>-->

        <dependency>

            <groupId>org.apache.tinkerpop</groupId>

            <artifactId>gremlin-server</artifactId>

            <version>${tinkerpop.version}</version>

        </dependency>

        <dependency>

            <groupId>org.janusgraph</groupId>

            <artifactId>janusgraph-hbase</artifactId>

            <version>${jg.version}</version>

            <!--<scope>runtime</scope>-->

        </dependency>

        <dependency>

            <groupId>org.janusgraph</groupId>

            <artifactId>janusgraph-es</artifactId>

            <version>${jg.version}</version>

        </dependency>

        <!--<dependency>-->

            <!--<groupId>org.apache.hbase</groupId>-->

            <!--<artifactId>hbase-common</artifactId>-->

            <!--<version>1.2.0-cdh5.12.1</version>-->

        <!--</dependency>-->

        <dependency>

            <groupId>org.apache.hbase</groupId>

            <artifactId>hbase-shaded-client</artifactId>

            <version>1.2.6</version>

            <!--<scope>runtime</scope>-->

        </dependency>

        <dependency>

            <groupId>org.elasticsearch.client</groupId>

            <artifactId>elasticsearch-rest-client</artifactId>

            <version>6.2.2</version>

        </dependency>

    </dependencies>

    <repositories>

        <repository>

            <id>maven-hadoop</id>

            <name>Hadoop Releases</name>

            <url>https://repository.cloudera.com/content/repositories/releases/</url>

            <snapshots>

                <enabled>false</enabled>

            </snapshots>

        </repository>

    </repositories>

</project>

1.5 JanusGraphDBTest类

这里直接先使用单元测试，初步判断下是否能够成功。

public class JanusGraphDBTest{

    protected static final String CONF_FILE = "src/main/resources/conf/janusgraph-hbase-es.properties";

    private static JanusGraphDB janusGraphDB;

    private static GraphTraversalSource g;

    private static JanusGraphManager gm;

    static {

        janusGraphDB = new JanusGraphDB(CONF_FILE);

        if(JanusGraphManagerUtility.getInstance()==null){

            gm = new JanusGraphManager(new Settings());

        }

        try {

            g = janusGraphDB.openGraph();

        } catch (ConfigurationException e) {

            e.printStackTrace();

        }

    }

    @Test

    public void createSchema(){

        janusGraphDB.createSchema();

        final JanusGraph janusGraph = (JanusGraph) g.getGraph();

        final JanusGraphManagement management = janusGraph.openManagement();

        final List<String> vertexLabels = StreamSupport.stream(management.getVertexLabels().spliterator(), false)

                .map(Namifiable::name).collect(Collectors.toList());

        final List<String> expectedVertexLabels = Stream.of("titan", "location", "god", "demigod", "human", "monster")

                .collect(Collectors.toList());

        assertTrue(vertexLabels.containsAll(expectedVertexLabels));

    }

    @Test

    public void selectCount(){

        Long count = g.V().count().next();

        System.out.println("CC+++++++:"+count.toString());

    }

    @Test

    public void dropGraph() throws Exception {

        janusGraphDB.dropGraph();

    }

}

单元测试成功的话，会在hbase中查看到对应创建的table。es索引创建可能不成功。这个我们后面章节再介绍进一步配置，先保证连接,建图成功。

2.踩坑过程中碰到的问题记录：    

2.1     Caused by:  java.lang.NoSuchMethodError:org.apache.hadoop.hbase.HTableDescriptor.addFamily(Lorg/apache/hadoop/hbase/HColumnDescriptor;)Lorg/apache/hadoop/hbase/HTableDescriptor;

 at org.janusgraph.diskstorage.hbase.HBaseCompat1_0.addColumnFamilyToTableDescriptor(HBaseCompat1_0.java:49)

 at org.janusgraph.diskstorage.hbase.HBaseStoreManager.createTable(HBaseStoreManager.java:761)

 at org.janusgraph.diskstorage.hbase.HBaseStoreManager.ensureTableExists(HBaseStoreManager.java:744)

 at org.janusgraph.diskstorage.hbase.HBaseStoreManager.getLocalKeyPartition(HBaseStoreManager.java:536)

 at org.janusgraph.diskstorage.hbase.HBaseStoreManager.getDeployment(HBaseStoreManager.java:375)

【解决方案】：hbase-shaded-client依赖包版本不对，这里使用hbase对应的版本版反而会报错，查看源码，需要和janusgraph-core对应的依赖包版本一致才行。可以在janusgraph-all中查看对应的版本号，然后单独引入对应的依赖即可。

2.2 

Caused by: java.lang.IllegalArgumentException: Could not instantiate implementation: org.janusgraph.diskstorage.es.ElasticSearchIndex

 at org.janusgraph.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:64)

 at org.janusgraph.diskstorage.Backend.getImplementationClass(Backend.java:476)

 at org.janusgraph.diskstorage.Backend.getIndexes(Backend.java:463)

 at org.janusgraph.diskstorage.Backend.<init>(Backend.java:148)

 at org.janusgraph.graphdb.configuration.GraphDatabaseConfiguration.getBackend(GraphDatabaseConfiguration.java:1840)

 at org.janusgraph.graphdb.database.StandardJanusGraph.<init>(StandardJanusGraph.java:138)

 at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:160)

 at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:131)

 at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:111)

 ... 30 more

Caused by: java.lang.reflect.InvocationTargetException

 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

 at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)

 at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

 at java.lang.reflect.Constructor.newInstance(Constructor.java:423)

 at org.janusgraph.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:58)

 ... 38 more

Caused by: org.janusgraph.diskstorage.PermanentBackendException: listener timeout after waiting for [30000] ms

【解决方案】：这里通过进一步查看debug日志，发现次连接es是成功的，说明es服务本身没有问题，所以初步定位问题出现在jar包上，通过尝试，更新elasticsearch-rest-client 的6.2.2版本jar包后解决。(查看日志发现应该是路由ip解析的问题，6.2.2版本jar包能够解析到本机的内网ip，而6.0.1版本解析不到。这里暂时不花时间深究。)

2.3

Caused by: java.lang.IllegalStateException: Gremlin Server must be configured to use the JanusGraphManager.

 at com.google.common.base.Preconditions.checkState(Preconditions.java:173)

 at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:148)

 at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:131)

 at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:111)

【解决方案】：这里需要初始化JanusGraphManager才能够创建graph实例。这个是在配置文件中配置了key：graph.graphname之后才会报错，需要在代码中手动初始化一下，因为JanusGraphManager是一个单例，所以直接初始化一下就行了。