JxBrowser

Note: Advice in this article will only work for JxBrowser 6. See the corresponding article for JxBrowser 7 here.(注意：本文中的建议仅适用于JxBrowser6，JxBrowser7相应文章请点击这里。)

JxBrowser DOM API provides functionality that allows evaluating XPath expressions. You can evaluation XPath expression in scope of DOMDocument or specified DOMNode. Both DOMDocument and DOMNode implements SearchContext interface that provides the following methods:(JxBrowser DOM API提供了允许评估XPath表达式的功能。您可以在DOMDocument或指定的DOMNode范围内评估XPath表达式。 DOMDocument和DOMNode都实现SearchContext接口，该接口提供以下方法：)

• XPathResult evaluate(String expression)
  
• XPathResult evaluate(String expression, XPathResultType type)
  

Sample code: (样例代码：)

DOMDocument document = browser.getDocument();
XPathResult result = document.evaluate("count(//div)");

The result of evaluation is stored in the XPathResult object. First you need to make sure that result is not an error and the evaluation completed successfully: (评估结果存储在XPathResult对象中。首先，您需要确保结果没有错误，并且评估成功完成：)

if (result.isError()) {
    System.out.println("Error: " + result.getErrorMessage());
    return;
}

Then you need to make sure that result contains expected value type (e.g. Number, Boolean, String, DOMNode) and extract the value itself: (然后，您需要确保结果包含预期的值类型（例如Number，Boolean，String，DOMNode）并提取值本身：)

if (result.isNumber()) {
    System.out.println("Result: " + result.getNumber());
}

or (要么)

if (result.isString()) {
    System.out.println("Result: " + result.getString());
}

or (要么)

if (result.isSingleNode()) {
    DOMNode node = result.getSingleNode();
    System.out.println("Result: " + node.getTextContent());
}

import com.teamdev.jxbrowser.chromium.Browser;
import com.teamdev.jxbrowser.chromium.XPathResult;
import com.teamdev.jxbrowser.chromium.dom.DOMDocument;
import com.teamdev.jxbrowser.chromium.events.FinishLoadingEvent;
import com.teamdev.jxbrowser.chromium.events.LoadAdapter;
import com.teamdev.jxbrowser.chromium.swing.BrowserView;

import javax.swing.*;
import java.awt.*;

/**
 * This sample demonstrates how to evaluate the XPath expression and work with the result.
 */
public class XPathSample {
    public static void main(String[] args) {
        final Browser browser = new Browser();
        BrowserView browserView = new BrowserView(browser);

        JFrame frame = new JFrame();
        frame.getContentPane().add(browserView, BorderLayout.CENTER);
        frame.setSize(800, 600);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);

        browser.addLoadListener(new LoadAdapter() {
            @Override
            public void onFinishLoadingFrame(FinishLoadingEvent event) {
                if (event.isMainFrame()) {
                    DOMDocument document = browser.getDocument();
                    XPathResult result = document.evaluate("count(//div)");
                    // If the expression is not a valid XPath expression or the document
                    // element is not available, we'll get an error.
                    if (result.isError()) {
                        System.out.println("Error: " + result.getErrorMessage());
                        return;
                    }

                    // Make sure that result is a number.
                    if (result.isNumber()) {
                        System.out.println("Result: " + result.getNumber());
                    }
                }
            }
        });
        browser.loadURL("http://www.teamdev.com/jxbrowser");
    }
}