如何从数据库中检索/设置ItemReader的SQL查询？

import org.springframework.batch.item.ItemReader;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;

import javax.sql.DataSource;
import java.sql.ResultSet;
import java.sql.SQLException;

public class DatabaseItemReader implements ItemReader<String> {

    private JdbcTemplate jdbcTemplate;
    private String sqlQuery;

    public DatabaseItemReader(DataSource dataSource, String sqlQuery) {
        this.jdbcTemplate = new JdbcTemplate(dataSource);
        this.sqlQuery = sqlQuery;
    }

    @Override
    public String read() throws Exception {
        return jdbcTemplate.queryForObject(sqlQuery, new RowMapper<String>() {
            @Override
            public String mapRow(ResultSet resultSet, int i) throws SQLException {
                return resultSet.getString("column_name");
            }
        });
    }
}