Android中ListView异步加载数据

1.主Activity

public class MainActivity extends Activity {

    private ListView listView;
    private ArrayList<Person> persons;
    private ListAdapter adapter;
    private Handler handler=null;
    //xml文件的网络地址
    final String path="http://192.168.5.10:8080/FileServer/person.xml";
    @SuppressLint("HandlerLeak")
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        listView=(ListView) super.findViewById(R.id.listview);
        //cache=new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/cache");
        
        //开一条子线程加载网络数据
        Runnable runnable=new Runnable()
        {
            public void run() 
            {
                try 
                {
                    Thread.sleep(2000);
                    //xmlwebData解析网络中xml中的数据
                    persons=XmlwebData.getData(path);
                    //发送消息，并把persons结合对象传递过去
                    handler.sendMessage(handler.obtainMessage(0, persons));
                } 
                catch (InterruptedException e) 
                {
                    e.printStackTrace();
                }
            }
        };

        try 
        {
            //开启线程
            new Thread(runnable).start();
            //handler与线程之间的通信及数据处理
            handler=new Handler()
            {
                public void handleMessage(Message msg) 
                {
                    if(msg.what==0)
                    {
                        //msg.obj是获取handler发送信息传来的数据
                        @SuppressWarnings("unchecked")
                        ArrayList<Person> person=(ArrayList<Person>) msg.obj;
                        //给ListView绑定数据
                        BinderListData(person);
                    }
                }
            };
        } 
        catch (Exception e) 
        {
            e.printStackTrace();
        }
    }
    
    //绑定数据
    public void BinderListData(ArrayList<Person> person)
    {
        //创建adapter对象
        adapter=new ListViewAdapter(R.layout.item,this,person);
        //将Adapter绑定到listview中
        listView.setAdapter(adapter);
    }
    
}

2.从网络中获取xml文件并解析数据

public class XmlwebData 
{
    private static ArrayList<Person> persons=null; 6     public static ArrayList<Person> getData(final String path)
    {
                try 
                {
                    URL url=new URL(path);
                    Person person=null;

                    HttpURLConnection conn=(HttpURLConnection) url.openConnection();
                    conn.setRequestMethod("GET");
                    conn.setConnectTimeout(5000);
                    if(conn.getResponseCode()==200)
                    {
                        InputStream inputstream=conn.getInputStream(); 
                        XmlPullParser xml=Xml.newPullParser();
                        xml.setInput(inputstream, "UTF-8");
                        int event=xml.getEventType();
                        
                        while(event!=XmlPullParser.END_DOCUMENT)
                        {
                            switch (event) 
                            {
                            //开始解析文档
                            case XmlPullParser.START_DOCUMENT:
                                persons=new ArrayList<Person>();
                                break;
                            case XmlPullParser.START_TAG:
                                
                                String value=xml.getName();
                                if(value.equals("person"))
                                {//person对象的初始化必须在这里初始化不然可能出现为null的现象
                                    person=new Person();
                                    //获取属性值
                                    person.setId(new Integer(xml.getAttributeValue(0)));
                                }
                                else if(value.equals("name"))
                                {
                                    person.setName(xml.nextText());
                                }
                                else if(value.equals("sex"))
                                {
                                    person.setSex(xml.nextText());
                                }
                                else if(value.equals("age"))
                                {
                                    person.setAge(new Integer(xml.nextText()));
                                }
                                else if(value.equals("path"))
                                {
                                    person.setPath(xml.nextText());
                                }
                                break;
                            case XmlPullParser.END_TAG:
                                if(xml.getName().equals("person"))
                                {
                                    persons.add(person);
                                    System.out.println(person.getName());;
                                    person=null;
                                }
                                break;
                            }
                            //解析下一个对象
                            event=xml.next();
                        }
                        return persons;
                    }
                } 
                catch (Exception e) 
                {
                    e.printStackTrace();
                } 
            
        
        return null;
    
    }

}

3.Person对象类

public class Person 
{
    private int id;
    private String name;
    private String sex;
    private String path;
    public String getPath() {
        return path;
    }
    public void setPath(String path) {
        this.path = path;
    }
    private int age;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public Person(){
        
    }
}

4.Adapter数据适配器类

public class ListViewAdapter extends BaseAdapter implements ListAdapter 
{

    private ArrayList<Person> data;
    private int id;
    private Context context;
    private LayoutInflater inflater;
    public ListViewAdapter(int item, MainActivity mainActivity,ArrayList<Person> data) 
    {
        this.data=data;
        this.context=mainActivity;
        this.id=item;
        inflater=LayoutInflater.from(context);
    }

    @Override
    public int getCount() 
    {
        return data.size();
    }

    @Override
    public Object getItem(int position) 
    {
        return data.get(position);
    }

    @Override
    public long getItemId(int position)
    {
        return position;
    }

    @Override
    public View getView(int position, View view, ViewGroup arg2)
    {
        TextView name=null;
        TextView sex=null;
        TextView age=null;
        ImageView img=null;
        if(view==null)
        {
            view=inflater.inflate(id, null);
            name=(TextView) view.findViewById(R.id.PersonName);
            sex=(TextView) view.findViewById(R.id.PersonSex);
            age=(TextView) view.findViewById(R.id.PersonAge);
            img=(ImageView) view.findViewById(R.id.Personimage);
            //保存view对象到ObjectClass类中
            view.setTag(new ObjectClass(name,sex,age,img));
        }
        else
        {
            //得到保存的对象
            ObjectClass objectclass=(ObjectClass) view.getTag();
            name=objectclass.name;
            sex=objectclass.sex;
            age=objectclass.age;
            img=objectclass.img;
        }
        
        Person person=(Person) data.get(position);
        //帮数据绑定到控件上
        name.setText(person.getName().toString());
        sex.setText("性别："+person.getSex().toString());
        age.setText("年龄："+String.valueOf(person.getAge()));
        //加载图片资源
        LoadImage(img,person.getPath());
        return view;
        
    }

    private void LoadImage(ImageView img, String path) 
    {
        //异步加载图片资源
        AsyncTaskImageLoad async=new AsyncTaskImageLoad(img);
        //执行异步加载，并把图片的路径传送过去
        async.execute(path);
        
    }

    private final class ObjectClass
    {
        TextView name=null;
        TextView sex=null;
        TextView age=null;
        ImageView img=null;
        public ObjectClass(TextView name, TextView sex, TextView age,ImageView img) 
        {
            this.name=name;
            this.sex=sex;
            this.age=age;
            this.img=img;
        }
    }
    
}

5.异步加载图片类

public class AsyncTaskImageLoad extends AsyncTask<String, Integer, Bitmap> {

    private ImageView Image=null;
    
    public AsyncTaskImageLoad(ImageView img) 
    {
        Image=img;
    }
    //运行在子线程中
    protected Bitmap doInBackground(String... params) {
        try 
        {
            URL url=new URL(params[0]);
            HttpURLConnection conn=(HttpURLConnection) url.openConnection();
            conn.setRequestMethod("POST");
            conn.setConnectTimeout(5000);
            if(conn.getResponseCode()==200)
            {
                InputStream input=conn.getInputStream();
                Bitmap map=BitmapFactory.decodeStream(input);
                return map;
            }
        } catch (Exception e) 
        {
            e.printStackTrace();
        }
        return null;
    }

    protected void onPostExecute(Bitmap result)
    {
        if(Image!=null && result!=null)
        {
            Image.setImageBitmap(result);
        }
        
        super.onPostExecute(result);
    }
}

6.网络中的person.xml文件内容为

<?xml version="1.0" encoding="UTF-8"?>
<Persons>
    <person id="1">
        <name>张三</name>
        <sex>男</sex>
        <age>25</age>
        <path>http://192.168.5.10:8080/FileServer/chengjisihan.jpg</path>
    </person>
    <person id="2">
        <name>李斯</name>
        <sex>男</sex>
        <age>78</age>
        <path>http://192.168.5.10:8080/FileServer/laozi.jpg</path>
    </person>
    <person id="3">
        <name>王五</name>
        <sex>男</sex>
        <age>22</age>
        <path>http://192.168.5.10:8080/FileServer/lilongji.jpg</path>
    </person>
    <person id="4">
        <name>庞聪</name>
        <sex>男</sex>
        <age>31</age>
        <path>http://192.168.5.10:8080/FileServer/lishimin.jpg</path>
    </person>
    <person id="5">
        <name>孙膑</name>
        <sex>男</sex>
        <age>48</age>
        <path>http://192.168.5.10:8080/FileServer/lisi.jpg</path>
    </person>
    <person id="6">
        <name>孙武</name>
        <sex>男</sex>
        <age>58</age>
        <path>http://192.168.5.10:8080/FileServer/liyuan.jpg</path>
    </person>
    
    <person id="7">
        <name>成吉思汗</name>
        <sex>男</sex>
        <age>40</age>
        <path>http://192.168.5.10:8080/FileServer/sunbiin.jpg</path>
    </person>
    
    <person id="8">
        <name>李渊</name>
        <sex>男</sex>
        <age>36</age>
        <path>http://192.168.5.10:8080/FileServer/sunwu.jpg</path>
    </person>
    
    <person id="9">
        <name>李隆基</name>
        <sex>男</sex>
        <age>32</age>
        <path>http://192.168.5.10:8080/FileServer/wangwu.jpg</path>
    </person>
    <person id="10">
        <name>武则天</name>
        <sex>女</sex>
        <age>55</age>
        <path>http://192.168.5.10:8080/FileServer/wuzetian.jpg</path>
    </person>
</Persons>

运行结果如下