readblobfromdb.java

来自「JAVA读取JPEG图象」· Java 代码 · 共 102 行

//package jdbcblob;
import javax.swing.*;
import java.io.*;
import java.sql.*;


/**
 * <p>Title: </p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2002</p>
 * <p>Company: </p>
 * @author unascribed
 * @version 1.0
 */
public class ReadBlobFromDb {
  Connection conn;
  Statement stmt;
  ResultSet rs;
  int bufferSize;

  public ReadBlobFromDb() throws SQLException,ClassNotFoundException {

    Class.forName("oracle.jdbc.driver.OracleDriver") ;

    String sourceURL="jdbc:oracle:thin:@localhost:1521:cnaloral";

    String user="system";

    String password="cnaloral8";

    conn=DriverManager.getConnection(sourceURL,user,password) ;

    stmt=conn.createStatement() ;

  }

  public void readFromDb(){
    String pathname,name;
    int amount=0;
    BufferedOutputStream out=null;
    InputStream in=null;

    JFileChooser chooser=new JFileChooser();
    int returnVal=chooser.showOpenDialog(null) ;

    if (returnVal==JFileChooser.APPROVE_OPTION) {

      pathname=chooser.getSelectedFile() .getAbsolutePath();
      name=chooser.getSelectedFile() .getName() ;
      chooser=null;

    }
    else {
      System.out.println("No file selected for writing data from DB!");
      System.out.println("Program terminating!");
      return;
    };
    try {
      rs=stmt.executeQuery("select data from media where trim(name)='"+name.trim()+"'") ;
      if (rs.next()) {
        Blob blob=rs.getBlob(1) ;
        in=blob.getBinaryStream() ;
        bufferSize=((oracle.sql.BLOB )blob).getBufferSize() ;
        out=new BufferedOutputStream(new FileOutputStream(pathname),(int)bufferSize);

        byte[] b=new byte[(int)bufferSize];
        int count=in.read(b,0,(int)bufferSize);

        while (count!=-1) {

          out.write(b,0,count);
          amount+=count;
          System.out.println("Processed "+amount+" bytes.");
          count=in.read(b,0,(int)bufferSize);

        };
        System.out.println("Processed "+amount+"bytes.Finished!");
        out.close();
        out=null;
        in.close();
        in=null;


      }
      else {
        System.out.println("The name "+name+" was not found in the media table!");

      };

    }
    catch (Exception ex) { ex.printStackTrace() ;

    }
    finally {
      if (out!=null) try{out.close() ;} catch(Exception ignored){};
      if (in!=null) try{in.close() ;} catch(Exception ignored){};
    }



  }
}