xpath即为xml路径语言(xml path language),它是一种用来确定xml文档中某部分位置的语言。xpath基于xml的树状结构,提供在数据结构树中找寻节点的能力。起初 xpath 的提出的初衷是将其作为一个通用的、介于xpointer与xsl间的语法模型。但是 xpath 很快的被开发者采用来当作小型查询语言。
xpathtest.java
import java.io.file;
import java.io.ioexception;
import javax.xml.parsers.documentbuilder;
import javax.xml.parsers.documentbuilderfactory;
import javax.xml.parsers.parserconfigurationexception;
import javax.xml.xpath.xpath;
import javax.xml.xpath.xpathconstants;
import javax.xml.xpath.xpathexpressionexception;
import javax.xml.xpath.xpathfactory;
import org.w3c.dom.document;
import org.w3c.dom.node;
import org.w3c.dom.nodelist;
import org.xml.sax.saxexception;
public class xpathtest {
public static void main(string[] args) throws parserconfigurationexception,
saxexception, ioexception, xpathexpressionexception {
// 解析文件,生成document对象
documentbuilder builder = documentbuilderfactory.newinstance()
.newdocumentbuilder();
document document = builder.parse(new file("bookstore.xml"));
// 生成xpath对象
xpath xpath = xpathfactory.newinstance().newxpath();
// 获取节点值
string webtitle = (string) xpath.evaluate(
"/bookstore/book[@category='web']/title/text()", document,
xpathconstants.string);
system.out.println(webtitle);
system.out.println("===========================================================");
// 获取节点属性值
string webtitlelang = (string) xpath.evaluate(
"/bookstore/book[@category='web']/title/@lang", document,
xpathconstants.string);
system.out.println(webtitlelang);
system.out.println("===========================================================");
// 获取节点对象
node bookweb = (node) xpath.evaluate(
"/bookstore/book[@category='web']", document,
xpathconstants.node);
system.out.println(bookweb.getnodename());
system.out.println("===========================================================");
// 获取节点集合
nodelist books = (nodelist) xpath.evaluate("/bookstore/book", document,
xpathconstants.nodeset);
for (int i = 0; i < books.getlength(); i++) {
node book = books.item(i);
system.out.println(xpath.evaluate("@category", book,
xpathconstants.string));
}
system.out.println("===========================================================");
}
}
bookstore.xml
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