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Android学习--解析XML数据格式

分类: 文章 • 2023-11-26 23:05:22

        在网络上传输数据时最常用的格式有两种：XML和JSON，首先学习如何解析XML格式的数据。

首先搭建一个apache服务器，确认工作正常。在Apache的htdocs目录下，新建一个get_data.xml文件，内容如下：

<apps>
    <app>
        <id>1</id>
        <name>Google Maps</name>
        <version>1.0</version>
    </app>
    <app>
        <id>2</id>
        <name>Chrome</name>
        <version>2.1</version>
    </app>
    <app>
        <id>3</id>
        <name>Google Play</name>
        <version>2.3</version>
    </app>
</apps>

在浏览器中验证 http://10.39.131.104/get_data.xml 可以访问 （IP依据实际情况而定）

1、Pull解析方式

布局文件activity_main.xml

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

主MainActivity中

package com.example.networktest;

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 org.json.JSONArray;
import org.json.JSONObject;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.StringReader;
import java.net.URL;

import javax.net.ssl.HttpsURLConnection;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParserFactory;

import okhttp3.FormBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class MainActivity extends AppCompatActivity {

    TextView responseText;
    Response response;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final Button sendRequest = (Button) findViewById(R.id.send_request);
        responseText = (TextView) findViewById(R.id.response_text);
        sendRequest.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                sendRequestWithOkHttp();
            }
        });
    }

    private void sendRequestWithOkHttp(){
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    OkHttpClient client = new OkHttpClient();
                    Request request = new Request.Builder()
                            .url("http://10.39.131.104/get_data.xml")
                            .build();
                    response = client.newCall(request).execute();
                    String responseData = response.body().string();
                    Log.d("MainActivity", "--responseData--"+responseData);
                    parseXMLWithPull(responseData);
//                    parseXMLWithSAX(responseData);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

    private void parseXMLWithPull(String xmlData){
        try {
            XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
            XmlPullParser xmlPullParser = factory.newPullParser()   
            xmlPullParser.setInput(new StringReader(xmlData));
            int eventType = xmlPullParser.getEventType();
            String id = "";
            String name = "";
            String version = "";
            while (eventType != XmlPullParser.END_DOCUMENT){
                String nodeName = xmlPullParser.getName();
                switch (eventType){
                    case XmlPullParser.START_TAG: {
                        if ("id".equals(nodeName)){
                            id = xmlPullParser.nextText();
                        }else if ("name".equals(nodeName)){
                            name = xmlPullParser.nextText();
                        }else if ("version".equals(nodeName)){
                            version = xmlPullParser.nextText();
                        }
                        break;
                    }
                    case 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);
                        }
                        break;
                    }
                    default:
                        break;
                }
                eventType = xmlPullParser.next();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

运行效果图(点击button)

Android学习--解析XML数据格式

2、SAX解析

需要新建一个类继承DefaultHandler，并重写父类5个方法

ContentHandler 类

package com.example.networktest;

import android.util.Log;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class ContentHandler extends DefaultHandler {

    private String nodeName;
    private StringBuilder id;
    private StringBuilder name;
    private StringBuilder version;

    @Override
    public void startDocument() throws SAXException {
        id = new StringBuilder();
        name = new StringBuilder();
        version = new StringBuilder();
    }

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        //记录当前节点名
        nodeName = localName;
    }

    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        //根据当前节点名判断内容添加到哪一个StringBuilder对象中
        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);
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
       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());
           //最后要将StringBuilder清空掉
           id.setLength(0);
           name.setLength(0);
           version.setLength(0);
       }
    }

    @Override
    public void endDocument() throws SAXException {
        super.endDocument();
    }
}

在MainActivity中修改代码

public class MainActivity extends AppCompatActivity {

    ......
    private void sendRequestWithOkHttp(){
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    OkHttpClient client = new OkHttpClient();
                    Request request = new Request.Builder()
                            .url("http://10.39.131.104/get_data.xml")
                            .build();
                    response = client.newCall(request).execute();
                    String responseData = response.body().string();
                    Log.d("MainActivity", "--responseData--"+responseData);
//                    parseXMLWithPull(responseData);
                    parseXMLWithSAX(responseData);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

    
    private void parseXMLWithSAX(String xmlData){
        try {
            SAXParserFactory factory = SAXParserFactory.newInstance();
            XMLReader xmlReader = factory.newSAXParser().getXMLReader();
            ContentHandler handler = new ContentHandler();
            //将ContentHandler的实例设置到XMLReader中
            xmlReader.setContentHandler(handler);
            //开始执行解析
            xmlReader.parse(new InputSource(new StringReader(xmlData)));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

运行效果

Android学习--解析XML数据格式

 

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