使用JdbcTemplate/JDBC流式读取数据库

JDBC原生实现

注意MySql中

conn.prepareStatement("select * from table",
                      ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY); 
// 这里因为MySQL驱动实现使用Integer.MIN_VALUE来判断是否使用流的方式
preparedStatement.setFetchSize(Integer.MIN_VALUE);

@Test
public void testCursor() throws ClassNotFoundException, SQLException {
    Class.forName("com.mysql.cj.jdbc.Driver");
    Connection connection = DriverManager
            .getConnection("jdbc:mysql://127.0.0.1:3306/db?useUnicode=true&characterEncoding=utf8&useSSL=false", 
                    "root", "root");
    PreparedStatement preparedStatement =
            connection.prepareStatement("select * from table",
                    ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
    preparedStatement.setFetchSize(Integer.MIN_VALUE);

    ResultSet resultSet = preparedStatement.executeQuery();

    while (resultSet.next()) {
        System.err.println(resultSet.getString("