Hive（三）：瞭解Hive的基本操做。

時間 2019-11-11

標籤 hive 瞭解基本欄目 Hadoop 简体版

原文原文鏈接

對Hive的一些基本操做作了個簡單的封裝，未建立Maven工程，至於須要的包，以及如何獲取HiveConnection請參考上一篇博文： http://my.oschina.net/gently/blog/683604java

一：首先，配置好鏈接Hive的Properties,建立hivedb.properties 以下：mysql

driver=org.apache.hive.jdbc.HiveDriver
url=jdbc:hive2://master:10000/default
user=hive
password=xujun

二：建立HiveProperties，繼承自Properties，讀取hivedb.properties（單例）sql

public class HiveProperties extends Properties {
	/**
	 * @author Berg
	 * 讀取hivedb.properties
	 */
	private static final long serialVersionUID = 1L;
	
	private static HiveProperties hiveProperties; 

	private HiveProperties(){
		InputStream iis = HiveProperties.class.getClassLoader().getResourceAsStream("hivedb.properties");
		try{
			super.load(  iis );
		}catch(IOException e ){
			e.printStackTrace();
		}
	}

	public static HiveProperties getInstance(){
		if( hiveProperties == null){
			hiveProperties = new HiveProperties();
		}
		return hiveProperties;
	}
}

三：建立HiveUtil，對Hive中的基本操做進行簡單封裝：apache

注意：導入數據的時候，能夠從本地文件導入數據，也能夠從HDFS上導入數據，oop

區別是：若是導入的是HDFS數據，則不須要local關鍵字測試

public class HiveUtil {

	//讀取一次驅動  靜態塊
	static{
		try {
			Class.forName(HiveProperties.getInstance().getProperty("driver"));
		}catch(ClassNotFoundException e){
			e.printStackTrace(); //輸出至標準錯誤流。
		}
	}

	//獲取HiveConnection
	public Connection getConn() throws SQLException{
		HiveProperties hp = HiveProperties.getInstance();
		Connection conn = DriverManager.getConnection(hp.getProperty("url"), 
				hp.getProperty("user"),  hp.getProperty("password") );
		return conn;

	}

	//建立表：
	public boolean createTable(Statement statement,String sql) throws SQLException{
		/**
		 * 若是第一個結果爲 ResultSet 對象，則返回 true
		 * 	若是其爲更新計數或者不存在任何結果，則返回 false
		 * 		由於 create 語法不屬於DML, 因此執行create sql語句後將返回false。	
		 * 			看起來仍是有點缺陷。 
		 */
		boolean result = statement.execute(sql);
		if( !result ){
			return true;
		}else{
			return false;
		}
	}

	//判斷表是否存在
	public boolean tableIsExists(Statement statement, String tableName) throws SQLException{
		String sql = "show tables '" + tableName + "'";
		ResultSet rs = statement.executeQuery(sql);  
		if (rs.next()) {  
			return true;  
		}else{
			return false;
		}
	}

	//刪除某張表：
	public boolean dropTable(Statement statement,String tableName) throws SQLException {
		String sql = "drop table " + tableName;
		boolean result = statement.execute(sql);
		if( !result ){
			return true;
		}else{
			return false;
		}
	}

	//顯示某張表或顯示全部的表
	public ResultSet showTables(Statement statement, String tableName) throws SQLException{
		String sql = "";
		if(tableName==null||tableName.equals(null)){
			sql = "show tables";
		}else{
			sql = "show tables '" + tableName + "'";
		}
		ResultSet rs = statement.executeQuery(sql);
		return rs;
	}

	//對錶的描述：
	public ResultSet describeTable(Statement statement, String tableName) throws SQLException   {
		String sql = "describe " + tableName;
		ResultSet rs = statement.executeQuery(sql);
		return rs;
	}

	/**
	 *經過文件方式,將文件中數據插入到表中：加載本地本劍數據。
	 * @throws SQLException 
	 * @filePath: 文件路徑,  好比： /home/hadoop/mytestdata/hive.txt
	 * 		注意此路徑在虛擬機下。。。
	 * */
	//經過文件方式,將文件中數據插入到表中：加載本地本劍數據。
	public boolean loadDataFromLocal(Statement statement, String tableName,String filePath) throws SQLException {
		String sql = "load data local inpath '" + filePath + "' into table " + tableName;
		boolean result = statement.execute(sql);
		if( !result ){
			return true;
		}else{
			return false;
		}
	}

	//經過文件方式,將文件中數據插入到表中：加載本地本劍數據。
	public boolean loadDataFromHDFS(Statement statement, String tableName,String filePath) throws SQLException {
		String sql = "load data inpath '" + filePath + "' into table " + tableName;
		boolean result = statement.execute(sql);
		if( !result ){
			return true;
		}else{
			return false;
		}
	}

	//查詢表中的數據：
	public ResultSet selectData(Statement statement, String tableName) throws SQLException  {
		String sql = "select * from " + tableName;
		ResultSet rs =  statement.executeQuery(sql);
		return rs;
	}

	//統計表中數據：
	public ResultSet countData(Statement statement, String sql) throws SQLException{
		ResultSet rs = statement.executeQuery(sql);
		return rs;
	}

	//關閉鏈接：
	public void  close(Connection conn,Statement statement) throws SQLException{
		if (conn != null) {  
			conn.close();  
			conn = null;  
		}  
		if (statement != null) {  
			statement.close();  
			statement = null;  
		}
	}
}

四：對基本操做的測試，以下建立TestMain：url

public class TestMain {

	private HiveUtil hu = new HiveUtil();
	private Connection conn = null;
	private Statement statement;
	//1.測試鏈接
	@Test
	public void testConn() throws SQLException{
		conn = hu.getConn();  
		System.out.println( "獲取鏈接爲： "+ conn );
	}

	//2.建立表：
	@Test
	public void testCreateTable() throws SQLException{
		conn = hu.getConn();
		statement = conn.createStatement();
		String tableName = "testhive";
		String sql =  "create table " + tableName + " (key int, value string)  row format delimited fields terminated by '\t'";
		boolean result = hu.createTable(statement, sql);
		if( result ){
			System.out.println( "建立表成功。" + result  );
		}else{
			System.out.println( "建立表失敗。" + result );
		}
	}

	//3.判斷表是否存在
	@Test
	public void testTableIsExists() throws SQLException{
		conn = hu.getConn();
		statement = conn.createStatement();
		String tableName = "testhive";
		boolean result = hu.tableIsExists(statement, tableName);
		if(result){
			System.out.println( "表已經存在。" );
		}else{
			System.out.println( "表不存在,請新建表。");
		}
	}

	//4.刪除表：刪除表以前先判斷表是否存在。
	@Test
	public void testDropTable() throws SQLException{
		conn = hu.getConn();
		statement = conn.createStatement();
		String tableName = "testhive";
		boolean result = hu.tableIsExists(statement, tableName);
		if(result){
			System.out.println( "表已經存在,開始刪除這張表: " );
			result = hu.dropTable(statement, tableName);
			if( result ){
				System.out.println( "刪除表成功。");
			}else{
				System.out.println( "刪除表失敗。");
			}
		}else{
			System.out.println( "表不存在,請新建表。");
		}
	}

	//5.顯示全部的表
	@Test
	public void testShowTables() throws SQLException{
		conn = hu.getConn();
		statement = conn.createStatement();
		String tableName = "testhive";
		ResultSet rs = hu.showTables(statement, tableName);
		while( rs.next() ){
			System.out.println( "表名爲： "+ rs.getString(1));
		}
	}
	
	//6.對錶的描述
	@Test
	public void testDescribeTable() throws SQLException{
		conn = hu.getConn();
		statement = conn.createStatement();
		String tableName = "testhive";
		//首先判斷張表是否存在：
		boolean result = hu.tableIsExists(statement, tableName);
		if( result ){
			//表示表已經存在：
			ResultSet rs = hu.describeTable(statement, tableName);
			while( rs.next() ){
				System.out.println( rs.getString(1) );
			}
		}else{
			System.out.println( "Error: 表不存在,不能對錶描述。");
		}
	}

	//7.導入數據：  local 和 hdfs 
	@Test
	public void testLoadData() throws SQLException{
		conn = hu.getConn();
		statement = conn.createStatement();
		String tableName = "testhive";
		//String localFilePath = "/home/hadoop/mytestdata/hive.txt";  
		String hdfsFilePath = "hdfs://master:9000/user/hive/hive.txt";  
		//首先判斷張表是否存在：
		boolean result = hu.tableIsExists(statement, tableName);
		if( result ){
			//表示表已經存在：
			//加載導入本地數據
			//result = hu.loadDataFromLocal(statement, tableName, localFilePath);
			//加載導入HDFS上文件數據
			result = hu.loadDataFromHDFS(statement, tableName, hdfsFilePath);
			if( result ){
				System.out.println( "成功將本地文件數據導入到表" + tableName + "中" );
			}else{
				System.out.println(  " 導入失敗 。");
			}
		}else{
			System.out.println( "Error: 表不存在,不能對錶導入文件數據。");
		}
	}


	//8.查詢表中的數據：
	@Test
	public void testSelectData() throws SQLException{
		conn = hu.getConn();
		statement = conn.createStatement();
		String tableName = "testhive";
		//首先判斷張表是否存在：
		boolean result = hu.tableIsExists(statement, tableName);
		if( result ){
			//表示表已經存在：
			ResultSet rs = hu.selectData(statement, tableName);
			while( rs.next() ){
				System.out.println( rs.getString(1) +"\t"+ rs.getString(2) );
			}
		}else{
			System.out.println( "Error: 表不存在,不能對錶導入文件數據。");
		}
	}


	//9.統計表中的數據：
	@Test
	public void testCountData() throws SQLException{
		conn = hu.getConn();
		statement = conn.createStatement();
		String tableName = "testhive";
		//首先判斷張表是否存在：
		boolean result = hu.tableIsExists(statement, tableName);
		if( result ){
			//表示表已經存在：
			String sql = "select count(1) from " + tableName; 
			ResultSet rs = hu.countData(statement, sql);
			System.out.println(  rs );
			while( rs.next() ){
				System.out.println( "當前記錄數據量爲： " + rs.getString(1)  );
			}
		}else{
			System.out.println( "Error: 表不存在,不能統計數據。");
		}
	}
	
}

5.測試數據：（以Tab隔開。）spa

1	Berg
1	Berg
2	Cccc
3	Xxxx
4	Jjjj

固然，也可建立Maven 的依賴，個人以下：.net

<dependencies>code

       <dependency>
           <groupId>junit</groupId>
           <artifactId>junit</artifactId>
           <version>4.12</version>
           <scope>test</scope>
       </dependency>

       <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>2.0.0</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>2.0.0</version>
       </dependency>

       <dependency>
           <groupId>mysql</groupId>
           <artifactId>mysql-connector-java</artifactId>
           <version>5.1.5</version>
       </dependency>

</dependencies>

以上依賴通過上述測試也是成功的。。。。

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