Struts and JSP

Struts makes it possible for JSP pages to externalize flow control, rather than specify physical links to various JSP pages within the JSP file, the JSP file contains a Struts-defined logical URI. The Struts URI defines a logical page request mapped to actions that may return different physical JSP pages depending on the context of the HTTP request.

Struts simplifies the development of the actual JSP file content by limiting it to user interface generation only. Java that would otherwise appear inside the JSP files appears in separate servlet action classes that the JSP page invokes at runtime.

Struts helps to separate the development roles into user interface designer (HTML or tag library user) and JSP action-handler developer. For example, one person can write JSP page using only HTML or suitable tag libraries, while another person works independently to create the page action handling classes in Java.

Struts externalizes JSP actions that would otherwise appear inside all the JSP pages of your project into a single configuration file. This greatly simplifies debugging and promotes reuse. Struts consolidates String resources that would otherwise appear inside all the JSP pages of your project into a single file. This simplifies the task of localizing JSP applications.

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Storing Images into Database using JDBC

We can store images into database using BLOB data type and also managing SQL 92 data types (BLOB, CLOB and Ref)

BLOB (Binary Large OBject)

• Used to store binary informations like images, audio files etc
• For each byte one byte of memory will be allocated
• Size can vary up to 4GB for each entry

CLOB (Character LOB)

• Used to store character information like plain, word documents
• For each character two bytes of memory is allocated
• Size up to 4GB

StoreImage.java

import java.sql.*;
import java.io.*;

public class StoreImage
{
public static void main(String rags[]) throws Exception
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection con=DriverManager.getConnection("jdbc:odbc:yourdsn","scott", "tiger");
PreparedStatement pstmt=con.prepareStatement
("insert into ImgStore values(?,?)");
File f=new File("pic.jpg");
FileInputStream fis=new FileInputStream(f);
pstmt.setInt(1, 1);
pstmt.setBinaryStream(2, fis, (int)f.length());
int i=pstmt.executeUpdate();
System.out.println(i+" record inserted");
pstmt.close();
con.close();
}
}

sqlplus scott/tiger
cle scr
--create table ImgStore (id number, image BLOB);

ImageRestore.java

import java.io.*;
import java.sql.*;

public class RestoreImage
{
public static void main(String rags[]) throws Exception
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection con=DriverManager.getConnection("jdbc:odbc:yourdsn","scott", "tiger");
Statement stmt=con.createStatement();
ResultSet rs=stmt.executeQuery("select * from temp");
if(rs.next())
{
System.out.println(rs.getInt(1));
InputStream in=rs.getBinaryStream(2);
FileOutputStream fos=new FileOutputStream("pic1.jpg");
int i=in.read();
while(i!=-1)
{
fos.write(i);
i=in.read();
}
fos.close();
in.close();
}
rs.close();
stmt.close();
con.close();
}
}

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