此處僅僅是去解析最基本的XML檔案，XML檔案如下：

<Books>
    <Book>
        <Name>Java入門</Name>
        <Price>30.00</Price>
    </Book>
    <Book>
        <Name>Java基礎</Name>
        <Price>130.00</Price>
    </Book>
    <Book>
        <Name>Java精通</Name>
        <Price>
 
256.00</Price>
    </Book>
    <Book>
        <Name>Java進階</Name>
        <Price>998.00</Price>
    </Book>
    <Book>
        <Name>程式設計師之禪</Name>
        <Price>122.00</Price>
    </Book>
    <Book>
        <Name>頸椎指南</Name>
 
        <Price>50.00</Price>
    </Book>
    <Book>
        <Name>活著</Name>
        <Price>26.00</Price>
    </Book>
    <Book/>
</Books>

上圖是一個書的XML檔案，我們建立一個Book類用來儲存上面的圖書實體

package learn;
public class Book implements Comparable<Book>{
    private 
 
String name;
    private float price;
    public Book() {
    }

    public Book(String name, float price) {
        this.name = name;
        this.price = price;
}

    public String getName() {
        return name;
}

    public void setName(String name) {
        this.name = name;
}

    public float getPrice() {
        return price;
}

    public void setPrice(float price) {
        this.price = price;
}

    @Override
public String toString() {
        return "Book{" +
                "name='" + name + '\'' +
                ", price=" + price +
                '}';
}

    @Override
public int hashCode() {
        System.out.println("Book.hashCode");
        return ((int) price);
}

    @Override
public boolean equals(Object obj) {
        System.out.println("Book.equals");
        if (obj instanceof Book) {
            Book book = (Book) obj;
            return price == book.price && name.equals(book.name);
}
        return false;
}

    @Override
public int compareTo(Book o) {
        int result = (int) (price - o.price);
        if (result == 0) {
            result = name.compareTo(o.name);
}
        return result;
}
}

下面是解析XML的程式碼

package learn;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Test01 {
    public static void main(String[] args) {
        String str = "<Books>\n" +
                "    <Book>\n" +
                "        <Name>Java入門</Name>\n" +
                "        <Price>30.00</Price>\n" +
                "    </Book>\n" +
                "    <Book>\n" +
                "        <Name>Java基礎</Name>\n" +
                "        <Price>130.00</Price>\n" +
                "    </Book>\n" +
                "    <Book>\n" +
                "        <Name>Java精通</Name>\n" +
                "        <Price>256.00</Price>\n" +
                "    </Book>\n" +
                "    <Book>\n" +
                "        <Name>Java進階</Name>\n" +
                "        <Price>998.00</Price>\n" +
                "    </Book>\n" +
                "    <Book>\n" +
                "        <Name>程式設計師之禪</Name>\n" +
                "        <Price>122.00</Price>\n" +
                "    </Book>\n" +
                "    <Book>\n" +
                "        <Name>頸椎指南</Name>\n" +
                "        <Price>50.00</Price>\n" +
                "    </Book>\n" +
                "    <Book>\n" +
                "        <Name>活著</Name>\n" +
                "        <Price>26.00</Price>\n" +
                "    </Book>\n" +
                "    <Book/>\n" +
                "</Books>";
List<Book> list = null;
Stack<Book> stack = new Stack<>();
Pattern pattern = Pattern.compile("<(/?)([^<>/]+)(/?)>");//此正則可能匹配到的是<>
Matcher matcher = pattern.matcher(str);
Stack<Integer> last = new Stack<>();//用來存放匹配到的<>，裡面沒有/，記錄匹配到的<>的末尾位置
        while (matcher.find()) {
            if (matcher.group(1).isEmpty()) {  //如果<...>裡面的首個括號內是空
                last.push(matcher.end());      //記錄匹配到的<...>的末尾位置
                switch (matcher.group(2)) {
                    case "Books":
                        list = new ArrayList<>();
                        break;
                    case "Book":
                        stack.push(new Book());
                        break;
}
                if (!matcher.group(3).isEmpty()) {  //匹配第三個括號裡有/，即<../>
                    last.pop();                     //匹配到<../>，棧頂元素出棧
                    switch (matcher.group(2)) {
                        case "Book":
                            list.add(stack.pop());
                            break;
}

                }
            } else {

//如果</...>裡面的首個括號內不是空

Integer pop = last.pop(); //記錄上一個<..>或<../>的matcher.end() switch (matcher.group(2)) { case "Book": list.add(stack.pop()); break; case "Name": stack.peek().setName(str.substring(pop, matcher.start())); break; case "Price": stack.peek().setPrice(Float.parseFloat(str.substring(pop, matcher.start()))); break;} } } for (Book book : list) { //遍歷得到的list，裡面存入的是Book的實體 System.out.println(book);} }}