Question

我有下一个情况，我有一个像xml的字符串，我想搜索到这个字符串到第二个car_id（<car_id>12345678</car_id>）并获取值如果无法搜索car_type（<car_type id_1="2" id_2="32">55555</car_type>）我尝试了下面的代码，见下文，但工作不正常。是否有更好的方法来执行/循环字符串？谢谢并感谢Stackoverflow

的字符串：

<car_dealer><car_id>2</car_id></car_dealer><car><car_id>12345678</car_id></car>

<car_dealer><car_id>2</car_id></car_dealer><car><car_type id_1="2" id_2="32">55555</car_type></car>

代码：

 String carId = input.substring(input.lastIndexOf("<car_id>")+9, input.lastIndexOf("</car_id>"))
    String carType= input.substring(input.indexOf("<car><car_type>")+84, input.indexOf("</car>"))

Answer 1

我强烈建议您不要使用regex或indexOf -trick来解析这些字符串。那些总是会在某个时候破裂。

如果您的字符串确实看起来像xml实际上是xml，那么您可以使用xpath解析值。像这样：

import java.io.IOException;
import java.io.StringReader;

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.XPathExpression;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

public class A {

    public static void main(String[] args) throws Exception {
        XPathFactory xPathfactory = XPathFactory.newInstance();
        XPath xpath = xPathfactory.newXPath();

        String xml1 = "<xml><car_dealer><car_id>2</car_id></car_dealer><car><car_id>12345678</car_id></car></xml>";
        String xml2 = "<xml><car_dealer><car_id>2</car_id></car_dealer><car><car_type id_1=\"2\" id_2=\"32\">55555</car_type></car></xml>";

        Document doc1 = stringToDom(xml1);
        Document doc2 = stringToDom(xml2);

        XPathExpression expr1 = xpath.compile("//car/car_id/text()");
        String carId = (String) expr1.evaluate(doc1, XPathConstants.STRING);

        XPathExpression expr2 = xpath.compile("//car/car_type/text()");
        String carType = (String) expr2.evaluate(doc2, XPathConstants.STRING);

        System.out.println("***");
        System.out.println("carId: " + carId);
        System.out.println("carType: " + carType);
        System.out.println("***");

        /* prints 
           ***
           carId: 12345678
           carType: 55555
           ***
        */
    }

    public static Document stringToDom(String xmlSource) throws SAXException,
            ParserConfigurationException, IOException {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        return builder.parse(new InputSource(new StringReader(xmlSource)));
    }
}

Answer 2

您可以使用如下的模式匹配找到车辆ID。希望这会对你有所帮助。

String xmlString = "<car_id>12345678</car_id>afhkjasd<car_id>123456789</car_id>";
Pattern pattern = Pattern.compile("(<car_id>)([0-9]{0,})(</car_id>)");
Matcher matcher = pattern.matcher(xmlString);

while (matcher.find()) {
    System.out.println(matcher.group(2));
}

Answer 3

指数将完成这项工作：

原件： <car_dealer><car_id>2</car_id></car_dealer><car><car_id>12345678</car_id></car>

<car_dealer><car_id>2</car_id></car_dealer><car><car_type id_1="2" id_2="32">55555</car_type></car>

解决方案索引：

String car_id = input.substring(input.indexOf("<car><car_id>") + "<car><car_id>".length(), input.indexOf("</car_id></car>"));

为他人做同样的事。

祝你好运！

搜索不同的字符串

3 个答案: