引入依赖

<!-- https://mvnrepository.com/artifact/com.zaxxer/HikariCP -->
        <dependency>
            <groupId>com.zaxxer</groupId>
            <artifactId>HikariCP</artifactId>
            <version>2.5.1</version>
        </dependency>
          <!--oracle连接工具-->
        <dependency>
            <groupId>com.oracle</groupId>
            <artifactId>ojdbc6</artifactId>
            <version>12.1.0.2.0</version>
        </dependency>

编写配置文件：hikari.properties

jdbcUrl=jdbc:oracle:thin:@192.168.x.xx:1521:orcl
driverClassName=oracle.jdbc.driver.OracleDriver
dataSource.user=root
dataSource.password=root
dataSource.maximumPoolSize=100

接口实现类调用，使用静态代码块和饿汉模式

@Service
public class RealEstateServiceImpl implements RealEstateService {
	
 private static HikariDataSource hikariDataSource;

    // 静态代码块，只需要加载一次
    static {
        HikariConfig config = new HikariConfig("src/main/resources/hikari.properties");
        hikariDataSource = new HikariDataSource(config);
    }

    // 定义提供连接对象的方法
    // 饿汉模式
    private Connection conn() {
        try {
            // 获取连接对象
            return hikariDataSource.getConnection();
        } catch (Exception e) {
            e.getMessage();
        }
        return null;
    }

	
	//测试
	@Override
	 public List<String> getCLFDJ() {
		 //获取年份和区域
        List<String> years = queryCLFDJAllYear();
        return years;
	}

	//查询表中的所有年份
    private List<String> queryCLFDJAllYear() {
        List<String> list = new ArrayList<>();
        // try with自动关闭
        try (Connection conn = conn()) {
            //预编译
            String selectSql = "SELECT YEAR FROM BDCTJ_CLFDJ GROUP BY YEAR ORDER BY YEAR";
            PreparedStatement ptmt = conn.prepareStatement(selectSql); //预编译SQL，减少sql执行
            //执行,求所有
            ResultSet resultSet = ptmt.executeQuery();
            while (resultSet.next()) {
                list.add(resultSet.getString("YEAR"));
            }
            ptmt.close();
            resultSet.close();
        } catch (Exception e) {
            throw new RuntimeException(e.getMessage());
        }
        return list;
    }
}