From: http://www.pcdog.com/edu/mysql/20/11/f244110.html
背景！jsp+mysql 记住 要用mysql的longblob类型来存默认的blob大小不够
数据库字段：ｉｄ （ｃｈａｒ） ｐｉｃ （longblob）
转载请注明出处，这时我与我的知己的合作的结过
原来操作ｂｌｏｂ字段时都要先差个空值，在查ｂｌｏｂ，好麻烦，用ｐｒｅｐａｒｅＳｔａｔｍｅｎｔ就不用那么麻烦了，哈哈
postblob.heml页面
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>无标题文档</title></head><body><form action="testblob.jsp" method="post" ><table width="291" border="1"> <tr> <td width="107">id </td> <td width="168"><input name="id" type="text" /></td> </tr> <tr> <td>file</td> <td><input name="file" type="file" /></td> </tr> <tr> <td><input type="submit" value="提交"/></td> </tr></table></form></body></html>***************************************************************
testblob.jsp
<%@ page contentType="text/html;charset=gb2312"%> <%@ page import="java.sql.*" %><%@ page import="java.util.*"%><%@ page import="java.text.*"%><%@ page import="java.io.*"%> <html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>无标题文档</title></head><body><% String id=request.getParameter("id"); String file=request.getParameter("file"); out.print(id); out.print(file); FileInputStream str=new FileInputStream(file); out.print(str.available()); java.sql.Connection conn; java.lang.String strConn; Class.forName("org.gjt.mm.mysql.Driver").newInstance(); conn= java.sql.DriverManager.getConnection("jdbc:mysql://localhost/test","root",""); String sql="insert into test(id,pic) values(?,?)"; PreparedStatement pstmt=conn.prepareStatement(sql); pstmt.setString(1,id); pstmt.setBinaryStream(2,str,str.available()); pstmt.execute(); out.println("Success,You Have Insert an Image Successfully"); pstmt.close();%> <a href="readblob.jsp">查看图片</a><a href="postblob.html">返回</a></body></html>
********************************************************
readblob.jsp
<%@ page contentType="text/html;charset=gb2312"%> <%@ page import="java.sql.*, javax.sql.*" %><%@ page import="java.util.*"%><%@ page import="java.text.*"%><%@ page import="java.io.*"%> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>无标题文档</title></head>
<body><% java.sql.Connection conn; ResultSet rs=null; Class.forName("org.gjt.mm.mysql.Driver").newInstance(); conn= java.sql.DriverManager.getConnection("jdbc:mysql://localhost/test","root",""); Statement stmt=conn.createStatement(); rs=stmt.executeQuery("select * from test where id='1'"); if(rs.next()) { Blob b = rs.getBlob("pic"); int size =(int)b.length(); out.print(size); InputStream in=b.getBinaryStream(); byte[] by= new byte[size]; response.setContentType("image/jpeg"); ServletOutputStream sos = response.getOutputStream(); int bytesRead = 0; while ((bytesRead = in.read(by)) != -1) { sos.write(by, 0, bytesRead); } in.close(); sos.flush(); } %></body></html>********************************************************************
注意：在用sos.write(by, 0, bytesRead);时，该方法把inputstream中的内容在一个新的页面中输出，
如果本页中还有别的内容要输出的话，只有把上述方法改为，bytesRead = in.read(by)) ；
再用out.print(new String(by));方法输出结果，注意在这里不能用by.toString()方法，该方法返回的是要输出内容的内存地址。mysql中有blob textarea类型大小了66536基本上放点小的东东就足够了，哈哈，但是现在的数码ｐｉｃ越来越大就只能用longblob了 大小有４g能 ，放个电影都够了哈哈
