Java中通过JDBC远程连接Oracle数据库

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;

public class ConnectDB {
    public static void main(String[] args) {
        connectDB();
    }

    public static void connectDB() {
        Connection con = null;
        PreparedStatement pre = null;
        ResultSet results = null;
        ResultSetMetaData resultSetMetaData = null;
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            System.out.println("开始尝试连接数据库！");
            // 必须用oracle文件夹下"tnsnames.ora"配置文件中配置的连接字符串进行远程连接数据库
            String url = "jdbc:oracle:" + "thin:@(DESCRIPTION =" + "(ADDRESS_LIST ="
                    + "(ADDRESS = (PROTOCOL = TCP)(HOST = xxx)(PORT = xxx))" + ")" + "(CONNECT_DATA ="
                    + "(SERVICE_NAME = xxx)" + ")" + ")";
            String user = "xxx";
            String password = "xxx";
            con = DriverManager.getConnection(url, user, password);
            System.out.println("连接成功！");
            String sql = "select * from xxx";
            pre = con.prepareStatement(sql);
            System.out.println("开始执行SQL语句！");
            results = pre.executeQuery();
            resultSetMetaData = results.getMetaData();
            int columnCount = resultSetMetaData.getColumnCount();
            // 获取数据库表所有字段名及字段值类型
            for (int i = 1; i <= columnCount; i++) {
                System.out.println(resultSetMetaData.getColumnName(i) + ":" + resultSetMetaData.getColumnTypeName(i));
            }
            while (results.next()) {
                for (int i = 1; i <= columnCount; i++) {
                    System.out.print(results.getString(i)+"\t\t");
                }
                System.out.println();
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (results != null)
                    results.close();
                if (pre != null)
                    pre.close();
                if (con != null)
                    con.close();
                System.out.println("数据库连接已关闭！");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}