dragon.onlinedb
Class AbstractQuery

java.lang.Object
  |
  +--dragon.onlinedb.AbstractQuery

All Implemented Interfaces:

ArticleQuery, CollectionReader

Direct Known Subclasses:

AbstractSearchEngine, AmazonCatalogQuery, AmazonReviewQuery, CiteULikeTagQuery, PubMedQuery

public abstract class AbstractQuery

extends java.lang.Object

implements ArticleQuery

Abstract class for querying articles from a data source

Copyright: Copyright (c) 2005

Company: IST, Drexel University

Version:

1.0

Author:

Davis Zhou

Field Summary

protected int	articleNum
protected Article	curArticle
protected int	curArticleNo
protected int	curPageNo
protected int	curPageWidth
protected int	pageNum
protected int	pageWidth
protected ArticleParser	parser

Constructor Summary

AbstractQuery(int pageWidth)

Method Summary

void	close() Closes the collection reader and releases all occupied resources.
Article	getArticle() read out the article the current pointer points to.
protected abstract Article	getArticle(int articleNo)
java.lang.String	getArticleKey() In some cases, retrieval of an article is very expensive.
ArticleParser	getArticleParser() Gets the article parser of the collection reader
int	getCurPageNo()
int	getCurPageWidth()
Article	getNextArticle() Collection readers only support forward-only read mode.
int	getPageNum()
int	getPageWidth()
int	getTotalArticleNum()
boolean	loadCollection(java.lang.String collectionPath, java.lang.String collectionName)
boolean	moveToArticle(int paperNo) Move the pointer to the give position of the current page.
boolean	moveToNextArticle() The pointer will be set on the next article.
boolean	moveToNextPage() Move to the next page and the pointer is set on the first article of the page.
void	restart() The collection reader supports forward-only read mode.
void	setArticleParser(ArticleParser parser) Sets the article parse for the collection reader

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface dragon.onlinedb.ArticleQuery

initQuery, moveToPage, setSearchTerm

Methods inherited from interface dragon.onlinedb.CollectionReader

getArticleByKey, supportArticleKeyRetrieval

Field Detail

curPageNo

protected int curPageNo

curArticleNo

protected int curArticleNo

pageNum

protected int pageNum

articleNum

protected int articleNum

pageWidth

protected int pageWidth

curPageWidth

protected int curPageWidth

curArticle

protected Article curArticle

parser

protected ArticleParser parser

Constructor Detail

AbstractQuery

public AbstractQuery(int pageWidth)

Method Detail

getArticle

protected abstract Article getArticle(int articleNo)

getCurPageNo

public int getCurPageNo()

Specified by:

getCurPageNo in interface ArticleQuery

moveToNextPage

public boolean moveToNextPage()

Description copied from interface: ArticleQuery

Move to the next page and the pointer is set on the first article of the page.

Specified by:

moveToNextPage in interface ArticleQuery

Returns:

false if it reached the last page already.

getTotalArticleNum

public int getTotalArticleNum()

Specified by:

getTotalArticleNum in interface ArticleQuery

getPageNum

public int getPageNum()

Specified by:

getPageNum in interface ArticleQuery

getPageWidth

public int getPageWidth()

Specified by:

getPageWidth in interface ArticleQuery

getCurPageWidth

public int getCurPageWidth()

Specified by:

getCurPageWidth in interface ArticleQuery

Returns:

number of papers in the current page.

moveToNextArticle

public boolean moveToNextArticle()

Description copied from interface: ArticleQuery

The pointer will be set on the next article. After call the method of initQuery, one should call this method before you call getArticle to get the first article.

Specified by:

moveToNextArticle in interface ArticleQuery

Returns:

true if the current pointer is not on the last article.

moveToArticle

public boolean moveToArticle(int paperNo)

Description copied from interface: ArticleQuery

Move the pointer to the give position of the current page.

Specified by:

moveToArticle in interface ArticleQuery

Parameters:

paperNo - the position of the article in the current page.

Returns:

true if the position is within the scope of the current page.

getArticle

public Article getArticle()

Description copied from interface: ArticleQuery

read out the article the current pointer points to.

Specified by:

getArticle in interface ArticleQuery

Returns:

an article

getArticleKey

public java.lang.String getArticleKey()

Description copied from interface: ArticleQuery

In some cases, retrieval of an article is very expensive. Thus, one may check the key (unique document entry number) first. If the article is of interest, one will retrieve this article.

Specified by:

getArticleKey in interface ArticleQuery

Returns:

the key of the article the current pointer points to.

loadCollection

public boolean loadCollection(java.lang.String collectionPath,
                              java.lang.String collectionName)

getArticleParser

public ArticleParser getArticleParser()

Description copied from interface: CollectionReader

Gets the article parser of the collection reader

Specified by:

getArticleParser in interface CollectionReader

Returns:

the article parser

setArticleParser

public void setArticleParser(ArticleParser parser)

Description copied from interface: CollectionReader

Sets the article parse for the collection reader

Specified by:

setArticleParser in interface CollectionReader

Parameters:

parser - the article parser

getNextArticle

public Article getNextArticle()

Description copied from interface: CollectionReader

Collection readers only support forward-only read mode. When one call this method after calling restart method or creating the collection reader, it actually return the first article of the collection.

Specified by:

getNextArticle in interface CollectionReader

Returns:

the next article

close

public void close()

Description copied from interface: CollectionReader

Closes the collection reader and releases all occupied resources.

Specified by:

close in interface CollectionReader

restart

public void restart()

Description copied from interface: CollectionReader

The collection reader supports forward-only read mode. If one wants to scan the collection for the second time, it is required to call this method. Otherwise when one getNextArticle method, it always return null.

Specified by:

restart in interface CollectionReader