JDBC（八）批量处理

1.批量处理

1）批量处理可以提高速度

2）addBatch(String)：添加需要批量处理的SQL语句或是参数

3）executeBatch（）：执行批量处理语句

2. statement 批量测试

	@Test
	public void testBatchWithStatement(){
		Connection connection = null;
		Statement statement = null;
		String sql = null;
		
		try {
			connection = JDBCTools.getConnection();
			JDBCTools.startTransaction(connection);
			
			statement = connection.createStatement();
			
			long begin = System.currentTimeMillis();
			for(int i = 0; i < 100000; i++){
				sql = "INSERT INTO customers VALUES(" + (i + 1) 
						+ ", 'name_" + i + "', '29-6月 -13')";
				statement.addBatch(sql);
			}
			long end = System.currentTimeMillis();
			
			System.out.println("Time: " + (end - begin)); //39567
			
			JDBCTools.commitTransaction(connection);
		} catch (Exception e) {
			e.printStackTrace();
			JDBCTools.rollbackTransaction(connection);
		} finally{
			JDBCTools.releaseDB(null, statement, connection);
		}
	}

3. preparedStatement 批量测试

	@Test
	public void testBatchWithPreparedStatement(){
		Connection connection = null;
		PreparedStatement preparedStatement = null;
		String sql = null;
		
		try {
			connection = JDBCTools.getConnection();
			JDBCTools.startTransaction(connection);
			sql = "INSERT INTO customers VALUES(?,?,?)";
			preparedStatement = connection.prepareStatement(sql);
			Date date = new Date(new java.util.Date().getTime());
			
			long begin = System.currentTimeMillis();
			for(int i = 0; i < 100000; i++){
				preparedStatement.setInt(1, i + 1);
				preparedStatement.setString(2, "name_" + i);
				preparedStatement.setDate(3, date);
				
				preparedStatement.executeUpdate();
			}
			long end = System.currentTimeMillis();
			
			System.out.println("Time: " + (end - begin)); //9819
			
			JDBCTools.commitTransaction(connection);
		} catch (Exception e) {
			e.printStackTrace();
			JDBCTools.rollbackTransaction(connection);
		} finally{
			JDBCTools.releaseDB(null, preparedStatement, connection);
		}
	}

4. batch 测试

	@Test
	public void testBatch(){
		Connection connection = null;
		PreparedStatement preparedStatement = null;
		String sql = null;
		
		try {
			connection = JDBCTools.getConnection();
			JDBCTools.startTransaction(connection);
			sql = "INSERT INTO customers VALUES(?,?,?)";
			preparedStatement = connection.prepareStatement(sql);
			Date date = new Date(new java.util.Date().getTime());
			
			long begin = System.currentTimeMillis();
			for(int i = 0; i < 100000; i++){
				preparedStatement.setInt(1, i + 1);
				preparedStatement.setString(2, "name_" + i);
				preparedStatement.setDate(3, date);
				
				//"积攒" SQL 
				preparedStatement.addBatch();
				
				//当 "积攒" 到一定程度, 就统一的执行一次. 并且清空先前 "积攒" 的 SQL
				if((i + 1) % 300 == 0){
					preparedStatement.executeBatch();
					preparedStatement.clearBatch();
				}
			}
			
			//若总条数不是批量数值的整数倍, 则还需要再额外的执行一次. 
			if(100000 % 300 != 0){
				preparedStatement.executeBatch();
				preparedStatement.clearBatch();
			}
			
			long end = System.currentTimeMillis();
			
			System.out.println("Time: " + (end - begin)); //569
			
			JDBCTools.commitTransaction(connection);
		} catch (Exception e) {
			e.printStackTrace();
			JDBCTools.rollbackTransaction(connection);
		} finally{
			JDBCTools.releaseDB(null, preparedStatement, connection);
		}
	}