5.安卓基础之网络编程&开源框架&多线程下载

1. 简单的xml联网读取

• 需要在AndroidManifest.xml开启权限
  <uses-permission android:name="android.permission.INTERNET"/>

• 定义一个工具流

public class StreamTool {

    public static String decodeStream(InputStream in) throws Exception{

        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        byte[]buf = new byte[1024];
        int len = 0;
        while((len=in.read(buf))>0){
            baos.write(buf,0,len);
        }
        return baos.toString();
    }
}

• 定义一个NewsItem

public class NewsItem {

    private String title;
    private String description;
    private String image;
    private String type;
    private String comment;
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }
    public String getImage() {
        return image;
    }
    public void setImage(String image) {
        this.image = image;
    }
    public String getType() {
        return type;
    }
    public void setType(String type) {
        this.type = type;
    }
    public String getComment() {
        return comment;
    }
    public void setComment(String comment) {
        this.comment = comment;
    }

}

• 定义一个NewsService,通过处理数据返回List

public class NewsService {

    public static List<NewsItem> getAllNewsItem(final String path){

        final List<NewsItem> items = new ArrayList<NewsItem>();

        new Thread(){

            public void run() {

                try {
                    URL url = new URL(path);

                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();

                    //设置超时时间
                    conn.setConnectTimeout(5000);
                    conn.setRequestMethod("GET");

                    int code = conn.getResponseCode();

                    if(code==200){

                        InputStream in = conn.getInputStream();
                        XmlPullParser parser = Xml.newPullParser();
                        parser.setInput(in, "utf-8");
                        int type = parser.getEventType();
                        NewsItem item=null;
                        while(type!=XmlPullParser.END_DOCUMENT){

                            if(type==XmlPullParser.START_TAG){
                                if("item".equals(parser.getName())){
                                    item = new NewsItem();
                                }else if("title".equals(parser.getName())){
                                    item.setTitle(parser.nextText());
                                }else if("description".equals(parser.getName())){
                                    item.setDescription(parser.nextText());
                                }else if("image".equals(parser.getName())){
                                    item.setImage(parser.nextText());
                                }else if("type".equals(parser.getName())){
                                    item.setType(parser.nextText());
                                }else if("comment".equals(parser.getName())){
                                    item.setComment(parser.nextText());
                                }
                            }else if(type==XmlPullParser.END_TAG){

                                //将 item 添加到一个 list集合中
                                if(item!=null){
                                    items.add(item);
                                }
                            }
                            type = parser.next();
                        }
                    }
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }.start();

        return items;
    }
}

• 定义一个MainActivity

public class MainActivity extends AppCompatActivity {

    private String path = "http://www.itceo.net/test/news.xml";
    private List<NewsItem> items  =null;
    private ListView lv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        lv = (ListView) findViewById(R.id.lv);

        items = NewsService.getAllNewsItem(path);

        // 将item中的数据绑定到屏幕显示
        loadData();

    }

    //声明adapter
    private MyAdapter myadapter;

    private void loadData() {

        if(myadapter==null){

            myadapter = new MyAdapter();
            lv.setAdapter(myadapter);
        }else{
            //通知数据改变
            myadapter.notifyDataSetChanged();
        }
    }

    private class MyAdapter extends BaseAdapter{

        //指定到底有多少个item要显示在 lv 中
        @Override
        public int getCount() {
            return items.size();
        }

        //这个方法是在每次显示一个item时会被调用到的
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View v ;
            if(convertView==null){
                v=View.inflate(MainActivity.this, R.layout.item, null);
            }else{
                v = convertView;
            }

            //拿到当前位置newsItem对象
            NewsItem newsItem = items.get(position);



            //找到item中每个 控件
            SmartImageView siv = (SmartImageView) v.findViewById(R.id.item_iv);
            TextView title= (TextView) v.findViewById(R.id.item_title);
            TextView desc = (TextView) v.findViewById(R.id.item_desc);
            TextView type = (TextView) v.findViewById(R.id.item_type);

            title.setText(newsItem.getTitle());
            desc.setText(newsItem.getDescription());

            String tp = newsItem.getType();
            if("1".equals(tp)){
                //就是评论
                type.setText("评论: "+ newsItem.getComment());
                type.setTextColor(Color.YELLOW);

            }else if("2".equals(tp)){

                //就是视频
                type.setText("视频");
                type.setTextColor(Color.RED);

            }else if("3".equals(tp)){

                // 就是直播
                type.setText("Live直播 ");
                type.setTextColor(Color.BLUE);
            }
              //利用开源图片显示库
            siv.setImageUrl(newsItem.getImage());

            return v;
        }


        @Override
        public Object getItem(int position) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public long getItemId(int position) {
            // TODO Auto-generated method stub
            return 0;
        }

    }

}

• activity_main.xml与item.xml的编写

activity_main.xml:

<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"
    tools:context=".MainActivity" >

    <ListView
        android:id="@+id/lv"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        ></ListView>
</LinearLayout>

item.xml:

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

    <com.loopj.android.image.SmartImageView
        android:id="@+id/item_iv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true" />

    <TextView
        android:id="@+id/item_title"
        android:text="标题"
        android:layout_toRightOf="@id/item_iv"
        android:layout_width="fill_parent"
        android:textSize="20sp"
        android:layout_height="wrap_content"
        />
    <TextView
        android:id="@+id/item_desc"
        android:textSize="15sp"
        android:layout_below="@id/item_title"
        android:lines="2"
        android:text="描述xxxxxxxxxxxxxxxx"
        android:textColor="#55000000"
        android:layout_toRightOf="@id/item_iv"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        />
    <TextView
        android:id="@+id/item_type"
        android:layout_below="@id/item_desc"
        android:textSize="15sp"
        android:text="类型:"
        android:textColor="#55000000"
        android:layout_alignParentRight="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />
    <View
        android:background="#44ffffff"
        android:layout_width="fill_parent"
        android:layout_height="1dip"
        />
</RelativeLayout>

2. get与post的关系

2.1 get的关系

如果在发送数据的过程中,传输了中文数据,那么是需要进行url编码的,否则带不过去.

http://192.168.1.100:8080/web_login/login?number=%E5%93%88%E5%93%88&pwd=520
http://192.168.1.100:8080/web_login/login?number=5201314&pwd=520

path = path+"number="+URLEncoder.encode(number, "UTF-8")+"&pwd="+URLEncoder.encode(pwd, "UTF-8");

2.2 post的关系

URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();

conn.setRequestMethod("POST");
conn.setConnectTimeout(5000);

// Content-Type: application/x-www-form-urlencoded
conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");

//准备好数据  ---- number=erwan&pwd=456
String data = "number="+URLEncoder.encode(number, "utf-8")+"&pwd="+URLEncoder.encode(pwd, "utf-8");

//Content-Length: 20
conn.setRequestProperty("Content-Length", data.length()+"");

//这个地方表示告诉加了一个标志, 要给服务器写数据了
conn.setDoOutput(true);			
conn.getOutputStream().write(data.getBytes());

2.3 apache-httpclient-get

//客户端浏览器
HttpClient client = new DefaultHttpClient();

//get 方式请求的必要的参数
HttpGet get = new HttpGet(path);

//http://192.168.1.100:8080/web_login/login

//收到的来自于服务器端的响应的 数据
HttpResponse response = client.execute(get);

// HTTP/1.1 200 OK
int code = response.getStatusLine().getStatusCode();

2.4 apache-httpclient-post

//客户端浏览器
HttpClient client = new DefaultHttpClient();

//指定了发送的请求的方式
HttpPost post = new HttpPost(path);

//传递给服务器要带过去的参数的信息 				
List<NameValuePair> list = new ArrayList<NameValuePair>();

//将带过去的参数放到一个nameValuePair 中, 然后再放到 一个list 中,然后再将这个list给要带过去的数据实体
list.add(new BasicNameValuePair("number", number));
list.add(new BasicNameValuePair("pwd", pwd));

//设置带给服务器的参数的信息
//number=5201314&pwd=123

//设置要带给服务器的数据实体
post.setEntity(new UrlEncodedFormEntity(list,"UTF-8"));

//http://192.168.1.100:8080/web_login/login

//收到的来自于服务器端的响应的数据
HttpResponse response = client.execute(post);
//http 的相应分为响应行,响应头,响应体

//HTTP/1.1 200 OK
int code = response.getStatusLine().getStatusCode();

2.5 开源android-async-http-master-get

String path = "http://192.168.1.100:8080/web_login/login?number="+number+"&pwd="+pwd;
AsyncHttpClient client = new AsyncHttpClient();

client.get(path, new AsyncHttpResponseHandler() {

	//请求成功的时候  会被调用的
	@Override
	public void onSuccess(int statusCode, Header[] headers,
			byte[] responseBody) {
		tv_status.setText(new String(responseBody));
	}

	//请求失败的时候会被调用的
	@Override
	public void onFailure(int statusCode, Header[] headers,
			byte[] responseBody, Throwable error) {
		error.printStackTrace(System.out);
		Toast.makeText(MainActivity.this, "对不起, 俺错误了...", 0).show();
	}
});

2.6 开源android-async-http-master-post

String path = "http://192.168.1.100:8080/web_login/login";
AsyncHttpClient client = new AsyncHttpClient();

//封装了api , 使用到了handler 去 处理了 这些事儿 ...
RequestParams params = new RequestParams();

// number=5201314&pwd=123
params.add("number", number);
params.add("pwd", pwd);

client.post(path, params, new AsyncHttpResponseHandler(){
	@Override
	public void onSuccess(int statusCode, Header[] headers,
			byte[] responseBody) {
		tv_status.setText(new String(responseBody));
	}

	@Override
	public void onFailure(int statusCode, Header[] headers,
			byte[] responseBody, Throwable error) {
		error.printStackTrace(System.out);
		Toast.makeText(MainActivity.this, "出错误了 ", 0).show();
	}

});

3. 多线程与断点续传实现

public class ThreadDownload {
	//规定下载服务端的资源使用3条线程去下载

	private static int threadCount = 3;
	private static int currentRunningThread = 3;

	private static String path = "http://down.qq.com/cf/dltools/CrossFire_OBV4.0.5.0_Full_QQVIPDL_speeded_signed.exe";
	public static void main(String[] args) {

		try{
			URL url = new URL(path);
			HttpURLConnection conn = (HttpURLConnection) url.openConnection();

			conn.setConnectTimeout(5000);
			conn.setRequestMethod("GET");

			int code = conn.getResponseCode();

			if(code==200){
				//拿到文件的长度大小
				int length = conn.getContentLength();
				File file = new File(getFileName(path));

				RandomAccessFile raf = new RandomAccessFile(file, "rw");
				raf.setLength(length);
				raf.close();

				//启动线程去下载文件

				//获得每块线程的平均大小
				int blockSize = length / threadCount; //总文件长度大小/3

				//threadId:线程的id	threadcount:几条线程下载
				for(int threadId=0;threadId<threadCount;threadId++){

					int startIndex = threadId * blockSize; //0~2
					int endIndex = (threadId+1)*blockSize-1;//3~5

					//如果线程是最后的一个线程
					if(threadId==(threadCount-1)){
						endIndex = length-1;
					}
					new DownloadFilePartThread(threadId,startIndex,endIndex).start();

				}
			}
		}catch (Exception e) {
			e.printStackTrace();
		}
	}

	private static class DownloadFilePartThread extends Thread{
		//线程的id号
		private int threadId;
		//线程的下载开始位置
		private int startIndex;
		//线程的下载的结束位置
		private int endIndex;
		//当前线程下载到的位置
		private int currentPostion;

		public DownloadFilePartThread(int threadId,int startIndex,int endIndex){
			this.threadId = threadId;
			this.startIndex = startIndex;
			this.endIndex = endIndex;
			currentPostion = startIndex;
		}

		public void run(){
			System.out.println("第 " + threadId + "线程开始 下载了   : 下载  从 "
					+ startIndex + "~ " + endIndex);
			try{
				URL url = new URL(path);
				HttpURLConnection conn = (HttpURLConnection) url.openConnection();
				conn.setConnectTimeout(5000);
				conn.setRequestMethod("GET");

				// 在多线程下载的时候,每条线程只需要目标文件的一部分的数据
				// 需要告诉服务器,只需要那一段的数据
				// 通过设置 http的请求头可以去实现 ,告诉 服务器,只需要目标 段的数据

				// startIndex ---- endIndex
				conn.setRequestProperty("range", "bytes="+startIndex+"-"+endIndex);

				//获得服务器返回的目标段的数据
				File file = new File(getFileName(path));
				RandomAccessFile raf = new RandomAccessFile(file, "rw");

				File ilf = new File(threadId+".position");

				if(ilf.exists()&&ilf.length()>0){
					BufferedReader br = new BufferedReader(new FileReader(ilf));
					String vl = br.readLine();

					int alreadyWritePosition = Integer.parseInt(vl);
					//告诉服务器要数据的时候 ,从这个位置开始要
					conn.setRequestProperty("range", "bytes="+alreadyWritePosition+"-"+endIndex);

					raf.seek(alreadyWritePosition);
					System.out.println("下载过了!");
				}else{
					System.out.println("没下载过!");
					conn.setRequestProperty("range", "bytes="+startIndex+"-"+endIndex);

					//表示从哪里开始
					raf.seek(startIndex);
				}

				int code = conn.getResponseCode();
				if(code == 206){
					//拿到数据
					InputStream in = conn.getInputStream();

					int len = 0;
					byte[]buf = new byte[1024*1024*1024*1024*1024*1024*1024*1024*1024];
					while((len=in.read(buf))>0){
						raf.write(buf,0,len);
						//将实时的位置记录了之后,方便下面紧接着去往文件中去写
						currentPostion = currentPostion + len;
						File info = new File(threadId+".position");

						RandomAccessFile rf = new RandomAccessFile(info, "rwd");
						rf.write(String.valueOf(currentPostion).getBytes());
						rf.close();
					}
					in.close();
					raf.close();
				}
				System.out.println("第 " + threadId + "线程下载 结束了");
				// 等着所有的线程都下载完成再删文件
				// 弄一个 计数器,记住总共有多少条线程正在下载,每当一条线程下载完成,走到这里的时候,就将计数器-1 一下
				// 当发现计数器小于或者等于0 的时候,说明没有线程正在下载,所以这个时候,再去删记录了下载位置的文件
				synchronized (ThreadDownload.class) {
					currentRunningThread--;


					if(currentRunningThread<=0){
						//将记录下载位置的文件删除
						for(threadId=0;threadId<threadCount;threadId++){
							File fff = new File(threadId+".position");
							fff.renameTo(new File(threadId+".position.finish"));
							File fll = new File(threadId+".position.finish");
							fll.delete();
						}

					}
				}
			}catch (Exception e) {
				e.printStackTrace();
			}
		}

	}
	private static String getFileName(String path) {
		int index = path.lastIndexOf("/");
		return path.substring(index+1);
	}
}

4. 总结

多线程下载还需要深入了解.