Android使用SAX解析XML格式数据的操作步骤

<?xml version="1.0" encoding="utf-8"?>
<apps>
    <app id="1">
        <name>myapp</name>
        <version>1.0.0</version>
    </app>
    <app id="2">
        <name>anotherapp</name>
        <version>2.3.4</version>
    </app>
</apps>

import android.util.log
import org.xml.sax.attributes
import org.xml.sax.helpers.defaulthandler
​
class appcontenthandler : defaulthandler() {
    private var nodename = ""
    private lateinit var id: stringbuilder
    private lateinit var name: stringbuilder
    private lateinit var version: stringbuilder
​
    override fun startdocument() {
        id = stringbuilder()
        name = stringbuilder()
        version = stringbuilder()
    }
​
    override fun startelement(uri: string?, localname: string?, qname: string?, attributes: attributes?) {
        nodename = localname ?: ""
        if (localname == "app" && attributes != null) {
            log.d("appcontenthandler", "app id: ${attributes.getvalue("id")}")
        }
    }
​
    override fun characters(ch: chararray?, start: int, length: int) {
        when (nodename) {
            "name" -> name.append(ch, start, length)
            "version" -> version.append(ch, start, length)
        }
    }
​
    override fun endelement(uri: string?, localname: string?, qname: string?) {
        if (localname == "app") {
            log.d("appcontenthandler", "app name: ${name.tostring().trim()}")
            log.d("appcontenthandler", "app version: ${version.tostring().trim()}")
            name.setlength(0)
            version.setlength(0)
        }
    }
}

import org.xml.sax.inputsource
import java.io.stringreader
import javax.xml.parsers.saxparserfactory
​
fun parsexml(xmldata: string) {
    val factory = saxparserfactory.newinstance()
    val parser = factory.newsaxparser()
    val xmlreader = parser.xmlreader
    xmlreader.contenthandler = appcontenthandler()
    xmlreader.parse(inputsource(stringreader(xmldata)))
}

val xmldata = """
<apps>
    <app id="1">
        <name>myapp</name>
        <version>1.0.0</version>
    </app>
    <app id="2">
        <name>anotherapp</name>
        <version>2.3.4</version>
    </app>
</apps>
""".trimindent()
​
parsexml(xmldata)