由于项目中需要用到hive-jdbc从数据仓库拉数据下来，所以简单的学一下hive，hive数据仓库建构在hadoop集群之上，数据存在hdfs文件系统中，hive中执行的操作会装换成mapreduce作业进行执行，hive支持类似SQL的语言HQL，hive采用元数据对表进行管理，元数据有三种存放模式：嵌入模式，远程模式，本地模式；hive提供了强大的编程接口，hive jdbc可以让你如使用普通的jdbc一般来操作hive表以及数据。
1.添加依赖
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-hdfs</artifactId>
<version>2.6.4</version>
</dependency>
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-common</artifactId>
<version>2.6.4</version>
</dependency>
<dependency>
<groupId>org.apache.hive</groupId>
<artifactId>hive-exec</artifactId>
<version>1.1.0</version>
<exclusions>
<exclusion>
<artifactId>
pentaho-aggdesigner-algorithm
</artifactId>
<groupId>org.pentaho</groupId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.apache.hive</groupId>
<artifactId>hive-jdbc</artifactId>
<version>1.1.0</version>
</dependency>
2.jdbc连接hive
public class TestHive {
private static String driverName = "org.apache.hive.jdbc.HiveDriver";//jdbc驱动路径
private static String url = "jdbc:hive2://hiveserver.xxx.com:10000/dbName";//hive库地址+库名
private static String user = "username";//用户名
private static String password = "pwd";//密码
private static String sql = "";
private static ResultSet res;
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
try {
conn = getConn();
System.out.println(conn);
stmt = conn.createStatement();
String tableName="tab_name";//hive表名
sql = "select * from " + tableName;
System.out.println("Running:" + sql);
res = stmt.executeQuery(sql);
System.out.println("执行 select * query 运行结果:");
while (res.next()) {
System.out.println(res.getInt(1) + "\t" + res.getString(2));
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
System.exit(1);
} catch (SQLException e) {
e.printStackTrace();
System.exit(1);
} finally {
try {
if (conn != null) {
conn.close();
conn = null;
}
if (stmt != null) {
stmt.close();
stmt = null;
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
private static Connection getConn() throws ClassNotFoundException,
SQLException {
Class.forName(driverName);
Connection conn = DriverManager.getConnection(url, user, password);
return conn;
}
}
3.查询hive表数据
这个就和普通的jdbc差不太多，也是用sql的方式进行查询，具体的查询语法，可以参考hive官网
4.封装hive工具类
写完了再贴上来
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