mp3播放器(一)（从服务器端下载xml文件）

Mp3ListActivity.java

package com.example.mp3player00;

import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;

import xml.Mp3ListContentHandler;

import model.Mp3Info;

import com.example.download.HttpDownloader;

import android.os.Bundle;
import android.app.Activity;
import android.app.ListActivity;
import android.view.Menu;
import android.view.MenuItem;

public class Mp3ListActivity extends ListActivity {
    private static final int upadate=1;
    private static final int about=2;
   //以上定义常量，看到值的名字就知道按钮的名字    
   //且为后面修改提供方便
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_mp3_list);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_mp3_list, menu);
        menu.add(0, 1, 1,R.string.mp3list_update);
        menu.add(0, 2, 2, R.string.mp3list_about);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // TODO Auto-generated method stub
        //System.out.println("--->"+item.getItemId());
        if(item.getItemId()==upadate)
        {
            //用户点击了更新按钮
    
            String xml=downloadXML("http://192.168.1.100:8080/mp3/resources.xml");
            //System.out.println("----->"+xml);
            try {
                parse(xml);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        else if(item.getItemId()==about)
        {
            //用户点击了关于按钮
        }
        return super.onOptionsItemSelected(item);
    }
    //写一个单独的下载函数，更加清晰
    private String downloadXML(String urlStr) 
    {
        
        HttpDownloader httpdownloader=new HttpDownloader(); 
        String result=httpdownloader.download(urlStr);
        return result;
    }
    //在这个函数中解析xml
    //首先生成xml解析器
    private List<Mp3Info> parse(String xmlStr) throws IOException
    {
        SAXParserFactory saxParserFactory=SAXParserFactory.newInstance();
        try {
            XMLReader xmlReader=saxParserFactory.newSAXParser().getXMLReader();
            List<Mp3Info> info=new ArrayList<Mp3Info>();
            Mp3ListContentHandler  mp3ListContentHandler=new Mp3ListContentHandler(info);
            xmlReader.setContentHandler(mp3ListContentHandler);
            xmlReader.parse(new InputSource(new StringReader(xmlStr)));
            //解析完数据都天道info里面，然后用for循环迭代出来
            for (Iterator iterator = info.iterator(); iterator.hasNext();) {
                Mp3Info mp3Info = (Mp3Info) iterator.next();
                System.out.println(mp3Info);
            }
            
        } catch (SAXException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ParserConfigurationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        return null;
    }

}

HttpDownloader.java

package com.example.download;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class HttpDownloader {

    /**
     * 根据URL下载文件，前提是这个文件当中的内容是文本，函数的返回值就是文件当中的内容
     * 1.创建一个URL对象
     * 2.通过URL对象，创建一个HttpURLConnection对象
     * 3.得到InputStram
     * 4.从InputStream当中读取数据
     * @param urlStr
     * @return
     */
    public String download(String urlStr) {
        StringBuffer sb = new StringBuffer();
        String line = null;
        BufferedReader buffer = null;
        try {
            // 创建一个URL对象
            URL url = new URL(urlStr);
            // 创建一个Http连接
            HttpURLConnection urlConn = (HttpURLConnection) url
                    .openConnection();
            // 使用IO流读取数据
            buffer = new BufferedReader(new InputStreamReader(urlConn
                    .getInputStream()));
            while ((line = buffer.readLine()) != null) {
                sb.append(line);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                buffer.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return sb.toString();
    }
}

Mp3Info.java

package model;
/**
 * 把每一个<rescource>看成一个对象 mp3info对象 建一个实体类，代表现实中一个实体
 * Mp3info实体类
 * @author kyx
 */
public class Mp3Info {
   private String id;
   private String mp3Name;
   private String mp3Size;
   private String IrcName;
   private String IrcSize;
public String getId() {
    return id;
}
public void setId(String id) {
    this.id = id;
}
public String getMp3Name() {
    return mp3Name;
}
public void setMp3Name(String mp3Name) {
    this.mp3Name = mp3Name;
}
public String getMp3Size() {
    return mp3Size;
}
public void setMp3Size(String mp3Size) {
    this.mp3Size = mp3Size;
}
public String getIrcName() {
    return IrcName;
}
public void setIrcName(String ircName) {
    IrcName = ircName;
}
public String getIrcSize() {
    return IrcSize;
}
public void setIrcSize(String ircSize) {
    IrcSize = ircSize;
}
//还要生成一些构造函数，构造函数起码要有两个，一个是带参数的，一个是不带参数的
public Mp3Info(String id, String mp3Name, String mp3Size, String ircName,
        String ircSize) {
    super();
    this.id = id;
    this.mp3Name = mp3Name;
    this.mp3Size = mp3Size;
    IrcName = ircName;
    IrcSize = ircSize;
}
//不带参数的的构造函数
public Mp3Info() {
    super();
}
@Override
public String toString() {
    return "Mp3Info [id=" + id + ", mp3Name=" + mp3Name + ", mp3Size="
            + mp3Size + ", IrcName=" + IrcName + ", IrcSize=" + IrcSize + "]";
}
//toString方便测试鉴定
}

Mp3ContentHandler.java

package xml;

import java.util.List;

import model.Mp3Info;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
//解析
//内容处理器 ContentHandler 接口是解析xm的主体
//handler使用的是adapter的设计模式
//Adapter是连接后端数据和前端显示的适配器接口，
//是数据和UI（View）之间一个重要的纽带。在常见的View(ListView,GridView)等地方都需要用到Adapter
public class Mp3ListContentHandler extends DefaultHandler {
    private List<Mp3Info> info=null;//这边每次解析resource标签都会放入一个Mp3Info对象当中 ，一个标签就是一resource,再把每个对象放入List
    //Mp3ListActivity在调用此类的时候会生成List并且传进来
    private Mp3Info mp3info=null;//mp3info里面就是存放resource的值
    private String tagname;
    
    //添加get和set方便访问
    public List<Mp3Info> getInfo() {
        return info;
    }

    public void setInfo(List<Mp3Info> info) {
        this.info = info;
    }
    
    //Mp3ListActivity在调用此类的时候会生成List并且传进来
    public Mp3ListContentHandler(List<Mp3Info> info) {
        super();
        this.info = info;
    }

    @Override
   //遇到id这个标签，将值赋给Mp3Info的id属性
    public void characters(char[] ch, int start, int length)
            throws SAXException {
        // TODO Auto-generated method stub
        super.characters(ch, start, length);
        String temp=new String(ch,start,length);
        if(tagname.equals("id"))
        {
            mp3info.setId(temp);//如果标签是“id”，就把值赋予mp3info对象中的id变量中
        }
        else if(tagname.equals("mp3.name"))
        {
            mp3info.setMp3Name(temp);
        }
        else if(tagname.equals("mp3.size"))
        {
            mp3info.setMp3Size(temp);
        }
        else if(tagname.equals("Irc.name"))
        {
            mp3info.setIrcName(temp);
        }
        else if(tagname.equals("Irc.size"))
        {
            mp3info.setIrcSize(temp);
        }
        
    }

    @Override
    public void endDocument() throws SAXException {
        // TODO Auto-generated method stub
        super.endDocument();
    }

    @Override
    //标签解析结束
    public void endElement(String uri, String localName, String qName)
            throws SAXException {
        // TODO Auto-generated method stub
        super.endElement(uri, localName, qName);
        if(qName.equals("resource"))//这里用qName而不是tagname
        {
            info.add(mp3info);//如果遇到resource结尾，那么就把这个对象放入到List中
        }
        tagname="";
    }

    @Override
    public void startDocument() throws SAXException {
        // TODO Auto-generated method stub
        super.startDocument();
    }

    @Override
    //开始解析标签
    public void startElement(String uri, String localName, String qName,
            Attributes attributes) throws SAXException {
        // TODO Auto-generated method stub
        super.startElement(uri, localName, qName, attributes);
        this.tagname=localName;
        if(tagname.equals("resource"))
        {
            mp3info=new Mp3Info();
        }
    }

}

layout xml文件配合listView

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <LinearLayout android:id="@+id/listLinearLayout"
        android:layout_width="fill_parent" android:layout_height="wrap_content"
        android:orientation="vertical">
        <ListView android:id="@id/android:list" android:layout_width="fill_parent"
            android:layout_height="wrap_content" android:drawSelectorOnTop="true"
            android:scrollbars="vertical" />
    </LinearLayout>
</LinearLayout>

在Manifest中添加

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