import com.google.gson.JsonArray;
import org.json.JSONArray;
import org.json.JSONObject;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import oracle.sql.REF;

public class ServiceOracle {
    // 定义连接所需的字符串
    // 192.168.0.X是本机地址(要改成自己的IP地址)，1521端口号，XE是精简版Oracle的默认数据库名
    private static String USERNAMR = "KUSSDA";
    private static String PASSWORD = "KUSSDADBUSER";
    private static String DRVIER = "oracle.jdbc.OracleDriver";
    private static String URL = "jdbc:oracle:thin:@192.168.1.11:1521:mesdb";

    // 创建一个数据库连接
    Connection connection = null;
    // 创建预编译语句对象，一般都是用这个而不用Statement
    PreparedStatement pstm = null;
    // 创建一个结果集对象
    ResultSet rs = null;

    /**
     * 向数据库中查询数据
     */
    public JSONArray SelectData(String sql) {
        connection = getConnection();
        if (connection==null)return null;
        JSONArray array=null;
        try {
            pstm = connection.prepareStatement(sql);
            rs = pstm.executeQuery();
            array=new JSONArray();
            // 获取列数
            ResultSetMetaData metaData = rs.getMetaData();
            int columnCount = metaData.getColumnCount();
            while (rs.next()) {
                JSONObject jsonObj = new JSONObject();
                // 遍历每一列
                for (int i = 1; i <= columnCount; i++) {
                    String columnName =metaData.getColumnLabel(i);
                    String value = rs.getString(columnName);
                    jsonObj.put(columnName, value);
                }
                array.put(jsonObj);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            ReleaseResource();
        }
        return array;
    }
    /**
     * 获取Connection对象
     */
    public Connection getConnection() {
        try {
            Class.forName(DRVIER);
            connection = DriverManager.getConnection(URL, USERNAMR, PASSWORD);
            System.out.println("成功连接数据库");
        } catch (ClassNotFoundException e) {
            throw new RuntimeException("class not find !", e);
        } catch (SQLException e) {
            throw new RuntimeException("get connection error!", e);
        }

        return connection;
    }

    /**
     * 释放资源
     */
    public void ReleaseResource() {
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (pstm != null) {
            try {
                pstm.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}