Hatti matim tim, Ami mathe pari Dim: February 2008

Tuesday, February 26, 2008

Ugly duckling

A mother duck hatches her eggs and, while most of her ducklings are normal, one is grey, too large, and too clumsy to fit in among the others. Though she tries to accept him, the entire barnyard realizes that he simply does not belong and after a period of harassment he leaves to fend for himself. He is sheltered by an old woman in her poor cottage, but her cat and her hen will not accept him and he is forced to set off once again on his own. He wanders for the entire summer and fall, for no one will take him in, and he nearly freezes to death in an icy pond. Though he is rescued by a human, he cannot live in captivity, and he returns to the wild.

By the end of winter, he is miraculously still alive. He comes to a pond in a park or garden, where beautiful white swans are swimming. He is drawn to their beauty, though he has no reason to think that they will treat him better than anyone else has. Still, he thinks, even if they kill him, he must approach them. To his surprise, the beautiful creatures welcome and accept him; gazing at his reflection, he sees that he too is a swan. The children declare that he is the most beautiful swan of them all, yet he is not proud, for a good heart is never proud. Because of all that he suffered he now appreciates his happiness so much more.

Sunday, February 24, 2008

Struts2: dynamic file download

(there is a better method for this at the end of this post)

In struts2, file is downloaded as stream using StreamResult class.
To download file of dynamic name, size or type we need to extend this StreamResult class.

StreamResult result type takes the following parameters:

* contentType - the stream mime-type as sent to the web browser (default = text/plain).
* contentLength - the stream length in bytes (the browser displays a progress bar).
* contentDispostion - the content disposition header value for specifing the file name (default = inline, values are typically filename="document.pdf".
* inputName - the name of the InputStream property from the chained action (default = inputStream).
* bufferSize - the size of the buffer to copy from input to output (default = 1024).

Example:


<result name="success" type="stream">
 <param name="contentType">image/jpeg</param>
 <param name="inputName">imageStream</param>
 <param name="contentDisposition">filename="document.pdf"</param>

 <param name="bufferSize">1024</param>
</result>

So in the extended StreamResult class we need to set these parameters dynamically.
You could download source code from here, its same as following:


package downloadexample;
import org.apache.struts2.dispatcher.StreamResult;

import com.opensymphony.xwork2.ActionInvocation;

/**
 * This class for result-type="myStream"

 * 
 * <result-types> <result-type name="myStream" default="false"
 * class="downloadexample.DynamicStreamResult"/>
 * 
 * </result-types>

 * 
 * It extends StreamResult Used to download file as a stream.
 * 
 * @author sheetal
 * 
 */

public class DynamicStreamResult extends StreamResult{
 @Override

   protected void doExecute(String finalLocation, 
                     ActionInvocation invocation)
   throws Exception {

        //get name of downloaded file 
 String downloadedFileName = invocation.getStack().
              findValue(conditionalParse
("name", invocation));
  
 contentDisposition = "filename=\""

    +downloadedFileName + "\"";
  
 //get file size
 contentLength = ""+ invocation.getStack().findValue(
conditionalParse("size", invocation));
// get type of file
contentType = ""+ invocation.getStack().
                                     findValue(
conditionalParse("description", invocation));
        /*
          Executes the result given a final location 
         (jsp page, action, etc) and 
         the action invocation (the state in which 
         the action was executed).
        */
 super.doExecute(finalLocation, invocation);

 }

}

Let, our site is a search site where user inputs name of a file. our system searches the file in server's local directory and lets the user download it if found.

To do this, .jsp file should be include the following:


<s:form  action="downloadFile" validate="true"> 
                         
     <s:textfield label="Search file" 

                  name="name" required="true"/> 
     <s:textfield label="Define file type (image/jpeg, text/plain, application/pdf)" 
                  name="description" required="true"/> 
     <s:submit value="Find file"/>

 </s:form>

where downloadFile is the action for downloading file.

In your action class, add the following lines:


private String name; 
//holds name of downloaded file

private  InputStream inputStream; 
//holds stream of downloaded file
private String description; 
//holds the content type of the downloaded file

private long size; 
//holds the content size of the downloaded file


//method for downloading file
public String downloadFile() 
 {

 /*
          let, method searchFile(String fileName) 
           does the searching for us
          & returns InputStream of the file if found 
          and null otherwise.
        */
         this.inputStream = searchFile(name);

         if(inputStream !=null)
         {
           
           return Action.SUCCESS;

         }
         else
         {
            //handle error
            return Action.ERROR;

         } 
              
        
 }

//write setter getter methods
public InputStream getInputStream() throws Exception 

{
  return inputStream;

}

public String getName() 

{
   return name;
}
public void setName(String name) 

{
   this.name = name;
}
public String getDescription() 

{
 return this.description;
}
public void setDescription(String description) 

{
 this.description = description;
}
// write getter setter for attribute size

Now, edit your struts.xml file:


<!-- custom result type for file download -->
<result-types>
 <result-type name="myStream" 

 default="false"
 class="downloadexample.DynamicStreamResult"/>
</result-types>
<!-- action for downloading file-->
<action name="downloadFile" 

        method="downloadFile" 
        class="<action-class-name>">

     <result  type="myStream"/> 
     <result name="error">jsps/your_error_page.jsp</result> 


</action>

syntax highlighted by Code2HTML, v. 0.9.1

& we are done :D.

...................................................
May be a Better method:
the time i wrote this post i was too naive to find other solution for this. One person commented a quick solution on the blog.... thank you again. i haven't tried it, so i'm not sure if it works, check yourself...here is the comment.........

Actually, there's no need to extend the StreamResult class. You can dynamically pass the contentType (and other Stream parameters) by using parameter substitution in your Action mapping, like so:



 <result name="success" type="stream">

 <param name="contentType">${contentType}</param>
 <param name="inputName">imageStream</param>

 <param name="contentDisposition">filename="${fileName}"</param>

 <param name="bufferSize">${bufferSize}</param>

 </result>

You then add methods set/getContentType(), set/getFileName() and set/getBufferSize() to your Action class. In the Action method which handles your business logic, all you have to do is call this.setContentType(), this.setFileName() and this.setBufferSize() and supply whatever values you like.

---------------------------------------

Upload data to oracle using sql loader

Let,
I have a table named user in my oracle database.
Table creation commands:


create table user
(
id number,
name varchar(10)
);

To insert large amount of data (e.g. 1 million) row into that table, we could use sql loader. This utility (SQL LOADER)is used to load data from other data source into Oracle.

Steps for doing this:

1. write .csv file user.csv. Its a simple text file with comma separated data.
data are written in the following way:


1,"user1"
2,"user2"

2. copy user.csv file to the server where oracle is running. You could use ftp or ssh for this.

Let, user.csv is copied in /root/mycsv folder

3. write user.ctl file


LOAD DATA
INFILE '/root/mycsv/user.csv'
append into table user
FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
TRAILING NULLCOLS
(id,
name
)

Notes:

The LOAD DATA statement is required at the beginning of the control file.
The INFILE option specifies where the input file is located
Specifying BADFILE is optional. If you specify, then bad records found during loading will be stored in this file.
Specifying DISCARDFILE is optional. If you specify, then records which do not meet a WHEN condition will be written to this file.
You can use any of the following loading option

a. INSERT : Loads rows only if the target table is empty

b. APPEND: Load rows if the target table is empty or not.

c. REPLACE: First deletes all the rows in the existing table and then, load rows.

d. TRUNCATE: First truncates the table and then load rows.


FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'

This line indicates how the fields are separated in input file. Since in our case the fields are separated by “,” so we have specified “,” as the terminating char for fields. You can replace this by any char which is used to terminate fields. Some of the popularly use terminating characters are semicolon “;”, colon “:”, pipe “|” etc. TRAILING NULLCOLS means if the last column is null then treat this as null value, otherwise, SQL LOADER will treat the record as bad if the last column is null.

```
(id,
name
)
```
In this line specify the columns of the target table. Note how do you specify format for Date columns

4. execute the following command to load data from user.csv file to your database.


sqlldr userid=username/password@SIDname control='user.ctl' log='user.log'

5. If you don't know the SID name for oracle server, you can find it using following command:


echo $ORACLE_SID

if sid name was wrong, you'll get following error:


SQL*Loader-704: Internal error: ulconnect: OCIServerAttach [0]
ORA-12154: TNS:could not resolve the connect identifier specified

If the csv file is too large and tablespace is full, you'll get following error:




SQL*Loader-605: Non-data dependent ORACLE error occurred -- load discontinued.

Check your .log file and if you find the following if tablespace is full


ORA-01653: unable to extend table username.tablename by X in tablespace yourtablespace

To resolve this, you need to add another table space. Execute the following command to see current status of your tablespace:


select * from dba_data_files where tablespace_name = 'yourtablespace;

You'll find current something like the following:


FILE_NAME
----------------------------------------------
/usr/local/oracle/oradata/webct/yourtablespace01.dbf

 FILE_ID TABLESPACE_NAME                     BYTES     BLOCKS STATUS
---------- ------------------------------ ---------- ---------- ---------
      11 yourtablespace                  4294967296     524288 AVAILABLE

RELATIVE_FNO AUT   MAXBYTES  MAXBLOCKS INCREMENT_BY USER_BYTES USER_BLOCKS
------------ --- ---------- ---------- ------------ ---------- -----------
        11 YES 4294967296     524288        65536 4294443008      524224

Now you have to add more table space using following command:


alter tablespace USERS add datafile '/usr/local/oracle/oradata/webct/yourtablespace02.dbf' size 1024M autoextend on next 512M maxsize 4096M;

See details solution here.

Wednesday, February 20, 2008

Lights Up

Lights Up, originally uploaded by Inside_man.

Tuesday, February 19, 2008

The Witch of Portobello (complete and free!)

Browse Inside this book

Get this for your site

Friday, February 15, 2008

30 Largest Social Bookmarking Sites

30 Largest Social Bookmarking Sites | Updated 10/14/2007 | eBizMBA
Here are the 30 Largest Social Bookmarking Sites ranked by a combination of Inbound Links, Google Page Rank, Alexa Rank, and U.S. traffic data from Compete and Quantcast. Although no traffic metrics are completely accurate we do believe the data below to be useful for gauging relative audience size.

1 | digg.com
117,796,083 - Inbound Links | 16,964,445 - Compete Monthly Visitors | 8,700,000 - Quantcast Monthly Visitors | 98 - Alexa Ranking. | Page Rank: 8

Wednesday, February 13, 2008

Free bangla books download

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I will keep adding more books. stay tuned !!!

Meanwhile, think about those less fortunate people and donate

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Books that are really free: