Question

Java怎么做到把图片转换成流存入数据库，然后怎么再把图片显示出来。

Answer 1

首先创建一个空 Blob/Clob 字段，再从这个空 Blob/Clob字段获取游标，例如下面的代码：
PreparedStatement ps = conn.prepareStatement( " insert into PICTURE(image,resume) values(?,?) " );
// 通过oralce.sql.BLOB/CLOB.empty_lob()构造空Blob/Clob对象
ps.setBlob( 1 ,oracle.sql.BLOB.empty_lob());
ps.setClob( 2 ,oracle.sql.CLOB.empty_lob());
ps.excuteUpdate();
ps.close();
// 再次对读出Blob/Clob句柄
ps = conn.prepareStatement( " select image,resume from PICTURE where id=? for update " );
ps.setInt( 1 , 100 );
ResultSet rs = ps.executeQuery();
rs.next();
oracle.sql.BLOB imgBlob = (oracle.sql.BLOB)rs.getBlob( 1 );
oracle.sql.CLOB resClob = (oracle.sql.CLOB)rs.getClob( 2 );
// 将二进制数据写入Blob
FileInputStream inStream = new FileInputStream( " c://image.jpg " );
OutputStream outStream = imgBlob.getBinaryOutputStream();
byte [] buf = new byte [ 10240 ];
int len;
while (len = inStream.read(buf) > 0 ) {
outStream.write(buf, 0 ,len);
}
inStream.close();
outStream.cloese();
// 将字符串写入Clob
resClob.putString( 1 , " this is a clob " );
// 再将Blob/Clob字段更新到数据库
ps = conn.prepareStatement( " update PICTURE set image=? and resume=? where id=? " );
ps.setBlob( 1 ,imgBlob);
ps.setClob( 2 ,resClob);
ps.setInt( 3 , 100 );
ps.executeUpdate();
ps.close();