Cassandra資料庫Java訪問

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針對的時Cassandra 2.0 資料庫

Java本地用戶端訪問Cassandra，首先建立Java工程，使用Maven進行管理。

引入依賴：

<dependency>    <groupId>com.datastax.cassandra</groupId>    <artifactId>cassandra-driver-core</artifactId>    <version>2.1.0</version></dependency>

1. 類似Elasticsearch的方式，現在用戶端構建一個叢集對象：

Cluster cluster = Cluster.builder()                .addContactPoint("your ip")                .build();        Metadata metadata = cluster.getMetadata();        System.out.printf("Connected to cluster: %s\n",                metadata.getClusterName());        for (Host host : metadata.getAllHosts()) {            System.out.printf("Datatacenter: %s; Host: %s; Rack: %s\n",                    host.getDatacenter(), host.getAddress(), host.getRack());        }

2. 通過一個Session對象，實現對Cassandra的所有增刪改查。

Session session = cluster.connect();

3. 通過Session對象實現所有的DML等操作。 （PS：在對 Cassandra 進行操作之前，建議先瞭解 Cassandra 的架構以及資料群組織形式）

a. 我們首先建立一個Schema：

<pre name="code" class="java">ResultSet results = session.execute("SELECT * FROM simplex.playlists ");        System.out.println(String.format("%-30s\t%-20s\t%-20s\n%s", "title", "album", "artist",                "-------------------------------+-----------------------+--------------------"));        for (Row row : results) {            System.out.println(String.format("%-30s\t%-20s\t%-20s", row.getString("title"),                    row.getString("album"), row.getString("artist")));        }        System.out.println();

session.execute("CREATE KEYSPACE simplex WITH replication " + "= {‘class‘:‘SimpleStrategy‘, ‘replication_factor‘:3};");

b.建立一個Table：

session.execute(                "CREATE TABLE simplex.songs (" +                        "id uuid PRIMARY KEY," +                        "title text," +                        "album text," +                        "artist text," +                        "tags set<text>," +                        "data blob" +                        ");");

c. 插入資料：

session.execute(                "INSERT INTO simplex.songs (id, title, album, artist, tags) " +                        "VALUES (" +                        "756716f7-2e54-4715-9f00-91dcbea6cf50," +                        "'La Petite Tonkinoise'," +                        "'Bye Bye Blackbird'," +                        "'Joséphine Baker'," +                        "{'jazz', '2013'})" +                        ";");

d. 查詢資料：

ResultSet results = session.execute("SELECT * FROM simplex.playlists ");        System.out.println(String.format("%-30s\t%-20s\t%-20s\n%s", "title", "album", "artist",                "-------------------------------+-----------------------+--------------------"));        for (Row row : results) {            System.out.println(String.format("%-30s\t%-20s\t%-20s", row.getString("title"),                    row.getString("album"), row.getString("artist")));        }        System.out.println();

Cassandra資料庫Java訪問