我在尝试将blob图像显示到jsp页面时收到错误（＆＃34; pos＆＃34; +＆＃34;长度＆＃34;参数不能大于BLOB的长度）。我使用了两个不同的代码进行上传和检索。
upload.jsp
<%@ page import="java.sql.*"%>
<%@ page import="java.io.*"%>
<%
Connection con=null;
ResultSet rs=null;
PreparedStatement psmt=null;
FileInputStream fis;
String url="jdbc:mysql://localhost/logindb";
try{
Class.forName("com.mysql.jdbc.Driver").newInstance();
con=DriverManager.getConnection("jdbc:mysql://localhost:3306/logindb","root","");
File image=new File("F:/logo.png");
psmt=con.prepareStatement("insert into inimage(name,city,image)"+"values(?,?,?)");
psmt.setString(1,"Barack Obama");
psmt.setString(2,"Wasington D.C.");
fis=new FileInputStream(image);
psmt.setBinaryStream(3, (InputStream)fis, (int)(image.length()));
int s = psmt.executeUpdate();
if(s>0) {
%>
<b><font color="Blue"> <% out.println("Image Uploaded successfully !"); %>
</font></b>
<%
}
else {
out.println("unsucessfull to upload image.");
}
con.close();
psmt.close();
}catch(Exception ex){
out.println("Error in connection : "+ex);
}
%>
retrieveimage.jsp
<%@ page import="java.sql.*"%>
<%@ page import="java.io.*"%>
<% Blob image = null;
Connection con = null;
byte[ ] imgData = null ;
Statement stmt = null;
ResultSet rs = null;
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection("jdbc:mysql://localhost/logindb","root","");
stmt = con.createStatement();
rs = stmt.executeQuery("select * from inimage");
if (rs.next()) {
image = rs.getBlob(3);
imgData = image.getBytes(3,(int)image.length());
} else {
out.println("Display Blob Example");
out.println("image not found for given id>");
return;
}
// display the image
response.setContentType("image/gif");
OutputStream o = response.getOutputStream();
o.write(imgData);
o.flush();
o.close();
} catch (Exception e) {
out.println("Unable To Display image");
out.println("Image Display Error=" + e.getMessage());
return;
}finally {
/*try {
//rs.close();
//stmt.close();
//con.close();
} catch (SQLException e) {
e.printStackTrace();*/
}
%>