<base href="/bookstore/">的作用域
时间: 2023-12-23 10:02:48 浏览: 30
`<base href="/bookstore/">` 标签用于指定文档中所有相对 URL 的基础 URL。也就是说,如果在文档中使用了相对 URL,浏览器会将其解释为相对于 `<base>` 标签中指定的 URL。这样做的好处是,可以让文档中所有相对 URL 的解析方式保持一致,避免因为相对 URL 的解析方式不同而导致的错误。
例如,如果 `<base href="/bookstore/">` 存在于文档中,而文档中有一个相对 URL 是 `images/book.jpg`,浏览器会将其解析为 `http://example.com/bookstore/images/book.jpg`。如果没有 `<base>` 标签,浏览器可能会将其解析为 `http://example.com/images/book.jpg`。
相关问题
<?xml version="1.0" encoding="ISO-8859-1"?> <bookstore> <book category="children"> <author>J K. Rowling</author> <year>2005</year> <price>29.99</price> </book> <book category="cooking"> <author>Giada De Laurentiis</author> <year>2005</year> <price>30.00</price> </book> <book category="web"> <author>Erik T. Ray</author> <year>2003</year> <price>39.95</price> </book> <book category="web"> <author>James McGovern</author> <author>Per Bothner</author> <author>Kurt Cagle</author> <author>James Linn</author> <author>Vaidyanathan Nagarajan</author> <year>2003</year> <price>49.99</price> </book> </bookstore> 按照上述xml文件,使用html和javascript读取.xml文件的节点内容,以表格方式对内容进行显示,通过下拉单进行交互式书目内容选取,仅显示选中的书目信息
以下是实现该功能的示例代码:
HTML部分:
```html
<!DOCTYPE html>
<html>
<head>
<title>Interactive Bookstore</title>
</head>
<body>
<select id="category">
<option value="">Select a category</option>
<option value="children">Children</option>
<option value="cooking">Cooking</option>
<option value="web">Web</option>
</select>
<table id="bookTable">
<thead>
<tr>
<th>Author</th>
<th>Year</th>
<th>Price</th>
</tr>
</thead>
<tbody>
</tbody>
</table>
<script src="script.js"></script>
</body>
</html>
```
JavaScript部分:
```javascript
// 加载xml文件
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
displayBooks(this);
}
};
xhttp.open("GET", "books.xml", true);
xhttp.send();
// 处理选择器变化事件
document.getElementById("category").addEventListener("change", function() {
var selectedCategory = this.value;
var books = document.getElementsByTagName("book");
// 遍历所有书籍,根据类别显示或隐藏
for (var i = 0; i < books.length; i++) {
if (selectedCategory == "" || books[i].getAttribute("category") == selectedCategory) {
books[i].style.display = "table-row";
} else {
books[i].style.display = "none";
}
}
});
// 显示所有书籍
function displayBooks(xml) {
var xmlDoc = xml.responseXML;
var books = xmlDoc.getElementsByTagName("book");
var bookTable = document.getElementById("bookTable");
// 遍历所有书籍,并在表格中添加新行
for (var i = 0; i < books.length; i++) {
var row = bookTable.insertRow(-1);
row.setAttribute("category", books[i].getAttribute("category"));
row.style.display = "table-row";
var authorCell = row.insertCell(0);
var yearCell = row.insertCell(1);
var priceCell = row.insertCell(2);
authorCell.innerHTML = books[i].getElementsByTagName("author")[0].childNodes[0].nodeValue;
yearCell.innerHTML = books[i].getElementsByTagName("year")[0].childNodes[0].nodeValue;
priceCell.innerHTML = books[i].getElementsByTagName("price")[0].childNodes[0].nodeValue;
}
}
```
在该示例中,我们首先使用XMLHttpRequest对象加载books.xml文件。一旦文件加载完成,我们调用displayBooks函数来解析XML并在表格中显示所有书籍信息。
我们还在页面上添加了一个下拉单,使用户可以选择要显示的书籍类别。在选择器变化事件中,我们遍历所有书籍,并根据类别显示或隐藏它们。
在表格中显示书籍信息时,我们使用insertRow函数向表格添加新行,并使用insertCell函数向行添加新单元格。我们还使用getAttribute和getElementsByTagName函数从XML中获取书籍的类别、作者、年份和价格信息。
java使用builder设计模式解析这段xml:<?xml version="1.0" encoding="UTF-8"?><bookstore> <book category="children"> <title lang="en">Harry Potter</title> <author>J.K. Rowling</author> <year>2005</year> <price>29.99</price> </book> <book category="web"> <title lang="en">Learning XML</title> <author>Erik T. Ray</author> <year>2003</year> <price>39.95</price> </book></bookstore>
首先,我们需要定义一个Book类来表示XML中的每个书籍。这个类需要有四个属性:category、title、author和price。
然后,我们可以定义一个BookBuilder类来构建Book对象。BookBuilder类应该具有以下方法:
1. setCategory(String category):设置book的category属性。
2. setTitle(String title):设置book的title属性。
3. setAuthor(String author):设置book的author属性。
4. setYear(int year):设置book的year属性。
5. setPrice(double price):设置book的price属性。
6. build():构建一个Book对象并返回。
接下来,我们可以定义一个Bookstore类来表示整个XML文档。这个类应该具有一个List<Book>属性来存储所有的书籍。
最后,我们需要创建一个BookstoreBuilder类来解析XML文档并构建Bookstore对象。BookstoreBuilder类应该具有以下方法:
1. parseDocument(InputStream inputStream):解析XML文档并返回一个Bookstore对象。
下面是完整的代码实现:
Book.java
```
public class Book {
private String category;
private String title;
private String author;
private int year;
private double price;
public Book(String category, String title, String author, int year, double price) {
this.category = category;
this.title = title;
this.author = author;
this.year = year;
this.price = price;
}
// getters and setters
}
```
BookBuilder.java
```
public class BookBuilder {
private String category;
private String title;
private String author;
private int year;
private double price;
public BookBuilder setCategory(String category) {
this.category = category;
return this;
}
public BookBuilder setTitle(String title) {
this.title = title;
return this;
}
public BookBuilder setAuthor(String author) {
this.author = author;
return this;
}
public BookBuilder setYear(int year) {
this.year = year;
return this;
}
public BookBuilder setPrice(double price) {
this.price = price;
return this;
}
public Book build() {
return new Book(category, title, author, year, price);
}
}
```
Bookstore.java
```
import java.util.ArrayList;
import java.util.List;
public class Bookstore {
private List<Book> books;
public Bookstore() {
books = new ArrayList<>();
}
public void addBook(Book book) {
books.add(book);
}
// getters and setters
}
```
BookstoreBuilder.java
```
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import java.io.IOException;
import java.io.InputStream;
public class BookstoreBuilder {
public Bookstore parseDocument(InputStream inputStream) {
Bookstore bookstore = new Bookstore();
try {
SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser saxParser = factory.newSAXParser();
DefaultHandler handler = new DefaultHandler() {
private BookBuilder bookBuilder;
private String currentElement;
@Override
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
switch (qName) {
case "book":
bookBuilder = new BookBuilder();
bookBuilder.setCategory(attributes.getValue("category"));
break;
case "title":
case "author":
case "year":
case "price":
currentElement = qName;
break;
}
}
@Override
public void endElement(String uri, String localName, String qName) throws SAXException {
switch (qName) {
case "book":
bookstore.addBook(bookBuilder.build());
bookBuilder = null;
break;
case "title":
case "author":
case "year":
case "price":
currentElement = null;
break;
}
}
@Override
public void characters(char[] ch, int start, int length) throws SAXException {
if (currentElement != null) {
String value = new String(ch, start, length);
switch (currentElement) {
case "title":
bookBuilder.setTitle(value);
break;
case "author":
bookBuilder.setAuthor(value);
break;
case "year":
bookBuilder.setYear(Integer.parseInt(value));
break;
case "price":
bookBuilder.setPrice(Double.parseDouble(value));
break;
}
}
}
};
saxParser.parse(inputStream, handler);
} catch (ParserConfigurationException | SAXException | IOException e) {
e.printStackTrace();
}
return bookstore;
}
}
```
现在我们可以使用以下代码来解析XML文档并获取所有的书籍:
```
InputStream inputStream = new FileInputStream("bookstore.xml");
BookstoreBuilder bookstoreBuilder = new BookstoreBuilder();
Bookstore bookstore = bookstoreBuilder.parseDocument(inputStream);
List<Book> books = bookstore.getBooks();
for (Book book : books) {
System.out.println(book.getTitle() + " by " + book.getAuthor());
}
```