Hive 元数据统计表个数
流程图
flowchart TD
A(开始) --> B(连接Hive元数据)
B --> C(获取所有数据库)
C --> D(遍历数据库)
D --> E(获取数据库下的所有表)
E --> F(统计表个数)
F --> G(输出结果)
G --> H(结束)
类图
classDiagram
class HiveMetadata {
+ connect(): Connection
+ getAllDatabases(): List<String>
+ getAllTables(database: String): List<String>
+ countTables(tableList: List<String>): int
}
代码实现
首先,我们需要连接到 Hive 元数据数据库。可以使用 hive2
驱动程序来创建 JDBC 连接。
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class HiveMetadata {
private static final String HIVE_DRIVER = "org.apache.hive.jdbc.HiveDriver";
private static final String HIVE_URL = "jdbc:hive2://localhost:10000/default";
public Connection connect() {
Connection connection = null;
try {
Class.forName(HIVE_DRIVER);
connection = DriverManager.getConnection(HIVE_URL, "username", "password");
} catch (ClassNotFoundException | SQLException e) {
e.printStackTrace();
}
return connection;
}
}
接下来,我们需要获取所有的数据库。可以使用 SHOW DATABASES;
SQL 语句来查询所有的数据库。
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
public class HiveMetadata {
// ...
public List<String> getAllDatabases(Connection connection) {
List<String> databases = new ArrayList<>();
try {
Statement statement = connection.createStatement();
ResultSet resultSet = statement.executeQuery("SHOW DATABASES;");
while (resultSet.next()) {
databases.add(resultSet.getString(1));
}
} catch (SQLException e) {
e.printStackTrace();
}
return databases;
}
}
然后,我们需要遍历每个数据库,并获取每个数据库下的所有表。可以使用 SHOW TABLES IN database_name;
SQL 语句来查询某个数据库下的所有表。
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
public class HiveMetadata {
// ...
public List<String> getAllTables(Connection connection, String database) {
List<String> tables = new ArrayList<>();
try {
Statement statement = connection.createStatement();
ResultSet resultSet = statement.executeQuery("SHOW TABLES IN " + database + ";");
while (resultSet.next()) {
tables.add(resultSet.getString(1));
}
} catch (SQLException e) {
e.printStackTrace();
}
return tables;
}
}
接下来,我们需要统计表的个数。可以使用 size()
方法获取表列表的大小。
import java.util.List;
public class HiveMetadata {
// ...
public int countTables(List<String> tableList) {
return tableList.size();
}
}
最后,我们需要输出结果。可以使用 System.out.println()
方法打印统计结果。
public class HiveMetadata {
// ...
public void printResult(int tableCount) {
System.out.println("表的个数为:" + tableCount);
}
}
整体代码
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
public class HiveMetadata {
private static final String HIVE_DRIVER = "org.apache.hive.jdbc.HiveDriver";
private static final String HIVE_URL = "jdbc:hive2://localhost:10000/default";
public Connection connect() {
Connection connection = null;
try {
Class.forName(HIVE_DRIVER);
connection = DriverManager.getConnection(HIVE_URL, "username", "password");
} catch (ClassNotFoundException | SQLException e) {
e.printStackTrace();
}
return connection;
}
public List<String> getAllDatabases(Connection connection) {
List<String> databases = new ArrayList<>();
try {
Statement statement = connection.createStatement();
ResultSet resultSet = statement.executeQuery("SHOW DATABASES;");
while (resultSet.next()) {
databases.add(resultSet.getString(1));
}
} catch (SQLException e) {
e.printStackTrace();
}
return databases;
}
public List<String> getAllTables(Connection connection, String database) {
List<String> tables = new ArrayList<>();
try {
Statement statement = connection.createStatement();
ResultSet resultSet = statement.executeQuery("SHOW TABLES IN " + database + ";");
while (resultSet.next()) {
tables.add(resultSet.getString(1));
}
} catch (SQLException e) {
e.printStackTrace();
}
return tables;
}
public int countTables(List<String>