使用Java Pattern类对某些字符和数字进行正则表达式

Question

I have some XML in a String and want to replace all id attribute values by "" where the id attribute value starts with "widget".

Here is my input xml:

<panel height="24" id="sd1" layout="vertical" left_padding="12" spacing="12" stereotype="directions" width="790" x="0" y="79">
<text_widget halign="left" id="widget5019721000" width="761"/>
<text_widget halign="left" id="widget5019501000" width="761"/>
<text_widget halign="left" id="widget5019711000" width="761"/>
<text_widget halign="left" id="widget5019752000" width="761"/>
</panel>

And the output xml should be like below:

<panel height="24" id="sd1" layout="vertical" left_padding="12" spacing="12" stereotype="directions" width="790" x="0" y="79">
<text_widget halign="left" id="" width="761"/>
<text_widget halign="left" id="" width="761"/>
<text_widget halign="left" id="" width="761"/>
<text_widget halign="left" id="" width="761"/>
</panel>

I was trying using the code below:

String xmlStr = this.getXmlString();
Pattern pattern = Pattern.compile(xmlStr);
Matcher matcher = pattern.matcher(\"id="widget[0-9]\");

How do I do this using a regular expression in Java?

Answer 1

There's the error in your code though, Pattern.compile receive String parameter which is regex pattern, not source string. Here's the right code.

Pattern pattern = Pattern.compile("id=\\\"widget\d*")
Matcher match = pattern.matcher(xmlStr)
String result = match.replaceAll("id=\\\"")

Answer 2

String result = xml.replaceAll("id=\\\\\\"widget[0-9]*", "id=\\"");

Instead you can also use XML processing. Download JDOM from www.jdom.org and add the contained jdom-2.0.4.jar to your classpath. Then use the following code:

import java.io.StringReader;
import java.util.List;

import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.input.SAXBuilder;
import org.jdom2.output.Format;
import org.jdom2.output.XMLOutputter;

public class Test {
public static void main(String[] args) throws Exception {
    String xml = "<panel height=\"24\" id=\"sd1\" layout=\"vertical\" left_padding=\"12\" spacing=\"12\" stereotype=\"directions\" width=\"790\" x=\"0\" y=\"79\">"
                +"<text_widget halign=\"left\" id=\"widget5019721000\" width=\"761\"/>"
                +"<text_widget halign=\"left\" id=\"widget5019501000\" width=\"761\"/>"
                +"<text_widget halign=\"left\" id=\"widget5019711000\" width=\"761\"/>"
                +"<text_widget halign=\"left\" id=\"widget5019752000\" width=\"761\"/>"
                +"</panel>";

    SAXBuilder builder = new SAXBuilder();
    Document doc = builder.build(new StringReader(xml));

    List<Element> textWidgetElements = doc.getRootElement().getChildren("text_widget");
    for (Element e : textWidgetElements) {
        if (e.getAttributeValue("id").startsWith("widget")) {
            e.setAttribute("id", "");
        }
    }

    XMLOutputter out = new XMLOutputter();
    out.setFormat(Format.getPrettyFormat());
    String result = out.outputString(doc);

    System.out.println(result);
}

}