MainActivity.kt

package com.example.fredric.sendrequestwithokhttp

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.view.View
import android.widget.Button
import android.widget.TextView
import okhttp3.OkHttpClient
import okhttp3.Request
import org.xml.sax.InputSource
import org.xmlpull.v1.XmlPullParser
import org.xmlpull.v1.XmlPullParserFactory
import java.io.StringReader
import javax.xml.parsers.SAXParserFactory

class MainActivity : AppCompatActivity(), View.OnClickListener{


    var responseText: TextView? = null


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        var sendRequest = findViewById<Button>(R.id.send_request)
        responseText = findViewById<TextView>(R.id.response_text)

        sendRequest.setOnClickListener(this)
    }

    override fun onClick(v: View?) {
        if(v?.id == R.id.send_request) {
            sendRequestWithOkHttp()
        }
    }


    fun showResponse(responseData: String?) {
        runOnUiThread(object: Runnable{
            override fun run() {
                responseText?.setText(responseData)
            }
        })
    }

    fun parseXMLWithPull(responseData:String) {
        try {
            var factory = XmlPullParserFactory.newInstance()
            var pullParser = factory.newPullParser()
            pullParser.setInput(StringReader(responseData))
            var eventType = pullParser.eventType
            var id = ""
            var name = ""
            var version = ""

            while (eventType != XmlPullParser.END_DOCUMENT) {
                var nodeName = pullParser.name
                when(eventType) {
                    XmlPullParser.START_TAG -> {
                        if("id".equals(nodeName)) {
                            id = pullParser.nextText()
                        }else if("name".equals(nodeName)) {
                            name = pullParser.nextText()
                        }else if("version".equals(nodeName)) {
                            version = pullParser.nextText()
                        }
                    }

                    XmlPullParser.END_TAG -> {
                        if("app".equals(nodeName)) {
                            Log.d("MainActivity","id is: "+id)
                            Log.d("MainActivity","name is: "+name)
                            Log.d("MainActivity","version is: "+version)
                        }
                    }

                    else -> {

                    }
                }

                eventType = pullParser.next()
            }
        }catch (ex: Exception) {
            ex.printStackTrace()
        }
    }


    fun parseXMLWithSax(xmlData: String) {
        try {
            var factory = SAXParserFactory.newInstance()
            var xmlReader = factory.newSAXParser().xmlReader
            var handler = ContentHandler()
            xmlReader.contentHandler = handler
            xmlReader.parse(InputSource(StringReader(xmlData)))
        }catch (ex: Exception) {
            ex.printStackTrace()
        }
    }


    fun sendRequestWithOkHttp() {
        Thread(object: Runnable{
            override fun run() {
                try {
                    var client = OkHttpClient()
                    var request = Request.Builder().
                            url("http://192.168.0.102/get_data.xml").
                            build()
                    var response = client.newCall(request).execute()
                    var responseData = response.body().string()

                    showResponse(responseData)
//                    parseXMLWithPull(responseData)
                    parseXMLWithSax(responseData)
                }catch (ex: Exception) {
                    ex.printStackTrace()
                }
            }
        }).start()
    }
}

ContentHander.kt

package com.example.fredric.sendrequestwithokhttp

import android.util.Log
import org.xml.sax.Attributes
import org.xml.sax.SAXException
import org.xml.sax.helpers.DefaultHandler

class ContentHandler : DefaultHandler() {

    var nodeName: String? = null
    var id: StringBuilder? = null
    var name: StringBuilder? = null
    var version: StringBuilder? = null


    @Throws(SAXException::class)
    override fun startDocument() {
        id = StringBuilder()
        name = StringBuilder()
        version = StringBuilder()
    }


    @Throws(SAXException::class)
    override fun endDocument() {
        super.endDocument()
    }


    @Throws(SAXException::class)
    override fun startElement(uri: String, localName: String, qName: String, attributes: Attributes) {
        nodeName = localName
    }


    @Throws(SAXException::class)
    override fun characters(ch: CharArray, start: Int, length: Int) {
        if("id".equals(nodeName)) {
            id?.append(ch,start,length)
        }else if("name".equals(nodeName)) {
            name?.append(ch,start,length)
        }else if("version".equals(nodeName)) {
            version?.append(ch, start, length)
        }
    }

    @Throws(SAXException::class)
    override fun endElement(uri: String, localName: String, qName: String) {
        if("app".equals(localName)) {
            Log.d("ContentHandler","id is :" + id?.toString()?.trim())
            Log.d("ContentHandler","name is :" + name?.toString()?.trim())
            Log.d("ContentHandler","version is :" + version?.toString()?.trim())

            id?.setLength(0)
            name?.setLength(0)
            version?.setLength(0)
        }
    }

}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <Button
        android:id="@+id/send_request"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Send Request" />

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">


        <TextView
            android:id="@+id/response_text"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
           />
    </ScrollView>


</LinearLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.fredric.sendrequestwithokhttp">

    <uses-permission android:name="android.permission.INTERNET" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

运行效果，

Screen Shot 2018-07-23 at 7.07.46 AM.png