Java 搜索不同的字符串

我有下一种情况，我有一个类似xml的字符串，我想搜索这个字符串到第二个car_id 12345678并得到值 如果无法搜索车辆，请键入55555 我尝试了下面的代码，但效果不好。是否有更好的方法来执行/循环字符串？谢谢，谢谢Stackoverflow

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：

---

将完成此工作的索引：

原件： 212345678

255555

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>"));

对别人也一样

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祝你好运

您可以使用下面的模式匹配找到汽车id。希望这对你有帮助

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));
}

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我强烈建议您不要使用regex或indexOf-tricky解析这些字符串。这些东西总有一天会坏的

如果看起来非常像xml的字符串实际上是xml，那么可以使用xpath解析这些值。大概是这样的：

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)));
    }
}

---

使用XML解析API。我没有字符串。你也可以从字符串在内存中创建XML。不要开始用字符串操作解析xml，省去你自己的痛苦，使用类似xpatindexof的东西来完成这项工作，但不是很好，我想搜索不同的字符串执行此操作的关键是：子字符串的第一个索引是起始字符串示例：加上该字符串的长度，因为您最初得到它的第一个字符的索引。至于结束索引，只需指定结束字符串

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)));
    }
}