java 连接MYSQL 进行查询怎么修改

public class DataBase {

    private Connection conn = null;
    private Statement stmt = null;
    private ResultSet rs = null;

    public DataBase() {
        
        // oracle 的jdbc 连接
        try {
            OracleDataSource ds = new OracleDataSource();
            ds.setUser("uamqas02");
            ds.setPassword("uamqas02");
            ds.setURL("jdbc:oracle:thin:@localhost:1521:devdb01");
            conn = ds.getConnection();
            stmt = conn.createStatement();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }


    public ResultSet executeQuery(String sql) {
        rs = null;
        try {
            // stmt=conn.createStatement();
            rs = stmt.executeQuery(sql);
        } catch (SQLException e) {
            e.printStackTrace();
            System.err.println("executeQuerty:" + e.getMessage());
        }
        return rs;
    }

    // ---------------------------数据库的更新、修改、删除操作-------------------------------------------------
    public boolean executeUpdate(String sql) // 更新方法（增、删、改）
    {
        boolean temp = false;
        try {
            stmt = conn.createStatement();
            int i = stmt.executeUpdate(sql);
            if (i >= 1)
                temp = true;
        } catch (SQLException e) {
            e.printStackTrace();
            System.err.println("executeUpdate:" + e.getMessage());
        }
        return temp;
    }

    public boolean saveOrUpdateCommit(String sql, String sql2) {
        boolean temp = true;
        try {
            conn.setAutoCommit(false);
            stmt = conn.createStatement();
            stmt.addBatch(sql);
            stmt.addBatch(sql2);
            stmt.executeBatch();
            conn.commit();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            temp = false;
            // 回滚
            try {
                conn.rollback();
            } catch (SQLException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
        }
        try {
            conn.commit();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            temp = false;
            e.printStackTrace();
        }
        return temp;
    }

    public void closeStmt() {
        try {
            stmt.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void closeConn() {
        try {
            conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}