java 读取数据库 blob文件

1 /*
 2  * To change this template, choose Tools | Templates
 3  * and open the template in the editor.
 4  */
 5 
 6 package readblob;
 7 
 8 import com.mysql.jdbc.Blob;
 9 import com.unitedpacs.dbmanager.DB;
10 import com.unitedpacs.utils.ReadXML;
11 import java.io.File;
12 import java.io.FileNotFoundException;
13 import java.io.FileOutputStream;
14 import java.io.IOException;
15 import java.io.InputStream;
16 import java.sql.Connection;
17 import java.sql.ResultSet;
18 import java.sql.SQLException;
19 import java.util.logging.Level;
20 import java.util.logging.Logger;
21 
22 /**
23  *
24  * @author alen
25  */
26 public class Main {
27     private static DB db=new DB(ReadXML.getInstance().initJDBC());
28     /**
29      * @param args the command line arguments
30      */
31     public static void main(String[] args) throws FileNotFoundException, IOException {
32         try {
33             // TODO code application logic here
34             Connection conn = null;
35             ResultSet rs = null;
36             String sql = "select consor from risuser where userid='001'";
37             conn = db.getconnection();
38             rs = db.query(conn, null, sql);
39             if (rs.next()) {
40                 //获取 数据库中的  blob 
41                 Blob blob=(Blob)rs.getBlob(1);
42 
43                 //拿出 二进制流
44                 InputStream is=blob.getBinaryStream();
45 
46                 //文件输出流
47                 
48 
49                 
50                 int length=(int)blob.length();
51                 System.out.println("the blob length is "+length);
52 
53                 //定义缓冲区
54                 byte bt[] =new byte[length];
55                 try {
56                     //向缓冲区中 读取数据
57                     while ((length = is.read(bt)) != -1) {
58 
59                         //把缓冲区的述据 写出去
60                         fos.write(bt);
61                     }
62                     
63                 } catch (IOException ex) {
64                     Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
65                 }
66 
67                 //关闭输入流
68                 is.close();
69 
70                 //关闭输出流
71                 fos.close();
72                 
73             }
74         } catch (SQLException ex) {
75             Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
76         }
77 
78 
79     }
80 
81 }
82