java mysql 大文件的读取 java.sql.Blob

package day18;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.InputStream;import java.sql.Blob;import java.sql.ResultSet;import com.mysql.jdbc.Connection;import com.mysql.jdbc.PreparedStatement;import day17.DBManager;public class TestBlob {public static void main(String[] args) throws Exception {TestBlob t=new TestBlob();//t.savePic();t.readPic();}    public void readPic() throws Exception{//有问题    DBManager dbManager=null;Connection conn=null;PreparedStatement pstmt=null;ResultSet rs=null;dbManager=new DBManager();//获取连接conn=dbManager.getConnection();String sql="select * from pic where id=?";//FileInputStream fis=new FileInputStream(//new File("D:\\workspace\\WebDatabase\\src\\day18\\Penguins.jpg"));pstmt=(PreparedStatement) conn.prepareStatement(sql);pstmt.setInt(1,3);     Blob blob=null;rs=pstmt.executeQuery();if(rs.next()){blob=rs.getBlob(1);}//构造文件输出流FileOutputStream fos=new FileOutputStream("D:\\workspace\\WebDatabase\\src\\day18\\xxx.png");//构造缓冲输出流BufferedOutputStream bos=new BufferedOutputStream(fos);if(blob!=null){//获取读取图片的输入流InputStream ins=blob.getBinaryStream();BufferedInputStream bis=new BufferedInputStream(ins);//从输入流中获取数据写入到输出流int len=0;byte[] b=new byte[1024];while((len=bis.read(b))!=-1){//写入到输出流bos.write(b,0,len);}bos.close();bis.close();}//关闭资源dbManager.closeResource(conn,pstmt,rs);    }    public void savePic() throws Exception{    DBManager dbManager=null;Connection conn=null;PreparedStatement pstmt=null;dbManager=new DBManager();//获取连接conn=dbManager.getConnection();String sql="insert into pic(id,pic) values(?,?)";FileInputStream fis=new FileInputStream(new File("D:\\workspace\\WebDatabase\\src\\day18\\1.png"));pstmt=(PreparedStatement) conn.prepareStatement(sql);pstmt.setInt(1,3);pstmt.setBlob(2, fis);int k=pstmt.executeUpdate();System.out.println("k== "+k);//关闭资源dbManager.closeResource(conn,pstmt,null);    }}

DBManager.java 见上一篇。