重新认识Java-I/O流

package helloTest;

import com.fr.base.FRContext;
import com.fr.data.AbstractTableData;
import com.fr.general.data.TableDataException;
import com.fr.third.org.apache.poi.hssf.usermodel.HSSFSheet;
import com.fr.third.org.apache.poi.hssf.usermodel.HSSFWorkbook;

import java.io.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class ReadFile {
    private static PreparedStatement ps;
    

    /**
     * 读取保存在数据库中的文件到指定服务器文件夹下的文件
     * @auther SunJ 20190912
     * @param id
     * @return java.io.File
     */

    public File getFile(String id){
        String sql = " select filedata from credit.filedata where id = ? ";
        FRContext.getLogger().info("Query SQL of ParamTableDataDemo: \n" + sql);
        Connection conn = getConnection();
        File file = new File("D:\\root\\EFS\\data.xls");
        try {

            OutputStream outputStream = new FileOutputStream(file);
            ps = conn.prepareStatement(sql);
            ps.setString(1, id);
            ResultSet rs = ps.executeQuery();
            InputStream in = null;//文件数据输入流
            while (rs.next()) {
                in = rs.getBlob(1).getBinaryStream();
            }
            byte[] b = new byte[1024];
            int len = 0;
            while ( (len = in.read(b)) != -1) {
                outputStream.write(b, 0, len);//数据写入指定文件内
            }
            outputStream.close();
            in.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return file;
    }

    /**
     * 读取服务器文件。
     * @auther SunJ 20190912
     * @return boolean
     */
    public boolean inputDataToDb(String filePath){
        filePath = "D:\\root\\EFS\\data.xls";
        try {
            InputStream is = new FileInputStream(filePath);
            HSSFWorkbook excel = new HSSFWorkbook(is);
            for (int numSheet = 0; numSheet < excel.getNumberOfSheets(); numSheet++) {
                HSSFSheet sheet = excel.getSheetAt(numSheet);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    /**
     * 建立数据库连接
     * @auther SunJ 20190912
     * @return java.sql.Connection
     */
    public Connection getConnection() {

        String driverName = "oracle.jdbc.driver.OracleDriver";
        String url = "jdbc:oracle:thin:@10.116.50.123:1521/test";
        String username = "";
        String password = "";
        Connection con;
        try {
            Class.forName(driverName);
            con = DriverManager.getConnection(url, username, password);

        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
        return con;
    }

    public static void main(String[] args) {
        ReadFile ReadFile = new ReadFile();
        File file = ReadFile.getFile("b3448e077f3f4b229f30a86c604e23ab");
        System.out.println(file);
    }
}