import components.simplereader.SimpleReader;
import components.simplereader.SimpleReader1L;
import components.simplewriter.SimpleWriter;
import components.simplewriter.SimpleWriter1L;
import components.xmltree.XMLTree;
import components.xmltree.XMLTree1;
/**
* Program to convert an XML RSS (version 2.0) feed from a given URL into the
* corresponding HTML output file.
*
* @author Put your name here http://xml.weather.yahoo.com/forecastrss/43210.xml
*
*/
public final class RSSAggregator {
/**
* Private constructor so this utility class cannot be instantiated.
*/
private RSSAggregator() {
}
/**
* Outputs the opening tags in the generated HTML file.
*
* @param channel
* the channel element XMLTree
* @param out
* the output stream
* @updates {@code out.content}
* @requires
* {@code [the root of channel is a tag] and out.is_open}
*
* @ensures
* {@code out.content = #out.content * [the HTML opening tags]}
*
*/
private static void outputHeader(XMLTree channel, SimpleWriter out) {
assert channel != null : "Violation of: channel is not null";
assert out != null : "Violation of: out is not null";
assert channel.isTag() && channel.label().equals("channel") : ""
+ "Violation of: the label root of channel is a tag";
assert out.isOpen() : "Violation of: out.is_open";
out.println("");
out.println("");
out.println("");
int index = getChildElement(channel, "title");
String title = "";
if (index >= 0) {
title = channel.child(index).child(0).label();
out.println(title);
}
out.println("");
out.println("");
out.println("");
index = getChildElement(channel, "link");
if (index >= 0) {
String link = channel.child(index).child(0).label();
out.print("");
}
// TODO: Output Description
// TODO: Output table header
for (int i = 0; i < channel.numberOfChildren(); i++) {
if (channel.child(i).isTag()) {
if (channel.child(i).label() == "item") {
processItem(channel.child(i), out);
}
}
}
outputFooter(out);
}
/**
* Outputs the closing tags in the generated HTML file.
*
* @param out
* the output stream
* @updates {@code out.contents}
* @requires
* {@code out.is_open}
*
* @ensures
* {@code out.content = #out.content * [the HTML closing tags]}
*
*/
private static void outputFooter(SimpleWriter out) {
assert out != null : "Violation of: out is not null";
assert out.isOpen() : "Violation of: out.is_open";
out.println(" ");
out.println("");
out.println("");
/*
* TODO: fill in body
*/
}
/**
* Finds the first occurrence of the given tag among the children of the
* given {@code XMLTree} and return its index; returns -1 if not found.
*
* @param xml
* the {@code XMLTree} to search
* @param tag
* the tag to look for
* @return the index of the first child of type tag of the {@code XMLTree}
* or -1 if not found
* @requires
* {@code [the label of the root of xml is a tag]}
*
* @ensures
* {@code getChildElement =
* [the index of the first child of type tag of the {@code XMLTree} or
* -1 if not found]}
*
*/
private static int getChildElement(XMLTree xml, String tag) {
assert xml != null : "Violation of: xml is not null";
assert tag != null : "Violation of: tag is not null";
assert xml.isTag() : "Violation of: the label root of xml is a tag";
/*
* TODO: fill in body
*/
for (int i = 0; i < xml.numberOfChildren(); i++) {
if (xml.child(i).isTag()) {
if (xml.child(i).label() == tag) {
return i;
}
}
}
return -1;
}
/**
* Processes one news item and outputs one table row. The row contains three
* elements: the publication date, the source, and the title (or
* description) of the item.
*
* @param item
* the news item
* @param out
* the output stream
* @updates {@code out.content}
* @requires
* {@code [the label of the root of item is an - tag] and out.is_open}
*
* @ensures
* {@code out.content = #out.content *
* [an HTML table row with publication date, source, and title of news item]}
*
*/
private static void processItem(XMLTree item, SimpleWriter out) {
assert item != null : "Violation of: item is not null";
assert out != null : "Violation of: out is not null";
assert item.isTag() && item.label().equals("item") : ""
+ "Violation of: the label root of item is an - tag";
assert out.isOpen() : "Violation of: out.is_open";
out.println("
");
out.println("");
out.print("| ");
out.print("date");
out.println(" | ");
out.print("");
out.print("source");
out.println(" | ");
out.print("");
out.print("title");
out.println(" | ");
out.print("
");
out.println("");
dateCell(item, out);
sourceCell(item, out);
titleCell(item, out);
out.println("
");
}
private static void dateCell(XMLTree item, SimpleWriter out) {
int index = getChildElement(item, "pubDate");
String date = "";
out.print("");
if (index >= 0) {
date = item.child(index).child(0).label();
out.print(date);
} else {
out.print("No Source Available");
}
out.println(" | ");
}
private static void titleCell(XMLTree item, SimpleWriter out) {
out.print("");
int index = getChildElement(item, "title");
String title = "";
String link = "";
int index3 = getChildElement(item, "link");
if (index3 >= 0) {
link = item.child(index3).child(0).label();
out.print("");
}
if (index >= 0) {
title = item.child(index).child(0).label();
out.print(title);
} else {
int index2 = getChildElement(item, "description");
String description = "";
if (index2 >= 0) {
description = item.child(index2).child(0).label();
out.print(description);
} else {
out.print("No Source Available");
}
}
if (index3 >= 0) {
out.print("");
}
out.println(" | ");
}
private static void sourceCell(XMLTree item, SimpleWriter out) {
out.print("");
int index = getChildElement(item, "source");
String source = "";
String url = "";
if (index >= 0) {
source = item.child(index).child(0).label();
boolean urlexists = item.child(index).hasAttribute("url");
if (urlexists) {
url = item.child(index).attributeValue("url");
out.print("");
}
out.print(source);
if (urlexists) {
out.print("");
}
} else {
out.print("No Source Available");
}
out.println(" | ");
}
/*
* TODO: TODO: Output title with HTML table stuff TODO: Output description
* with HTML table stuff
*/
/**
* Main method.
*
* @param args
* the command line arguments; unused here
*/
public static void main(String[] args) {
SimpleReader in = new SimpleReader1L();
SimpleWriter out = new SimpleWriter1L();
out.println("enter url: ");
String url = in.nextLine();
XMLTree tree = new XMLTree1(url);
out.println("output file");
String file = in.nextLine();
SimpleWriter outFile = new SimpleWriter1L(file + ".html");
int index = getChildElement(tree, "channel");
outputHeader(tree.child(index), outFile);
in.close();
out.close();
}
}