Android中多线程下载

[java]
public class MainActivity extends Activity {

    // 声明控件
    // 路径与线程数量
    private EditText et_url, et_num;
    // 进度条
    public static ProgressBar pb_thread;
    // 显示进度的操作
    private TextView tv_pb;

    // 线程的数量
    public static int threadNum = 3;
    // 每个线程负责下载的大小
    public int blockSize;

    public static int threadCount;// 数量

    // 访问的path
    public String path;

    public static boolean flag = true;

    // 记录进度条的值
    public static int pb_count = 0;

    public static Handler handler;

    public static final int TEXTVALUE = 1;

    public static int pb_num = 0;
    public static int size = 0;

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

        et_url = (EditText) findViewById(R.id.et_path);
        et_num = (EditText) findViewById(R.id.et_threadNum);
        pb_thread = (ProgressBar) findViewById(R.id.pb_down);
        tv_pb = (TextView) findViewById(R.id.tv_pb);

        handler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                switch (msg.what) {
                case TEXTVALUE:
                    System.out.println("-----------------------"
                            + MainActivity.pb_count + "//////"
                            + MainActivity.size);

                    // 改变TEXTView
                    pb_num = (MainActivity.pb_count * 100) / MainActivity.size;
                    tv_pb.setText("当前进度是+" + pb_num + "%");
                    break;

                default:
                    break;
                }
            }
        };

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
    // getMenuInflater().inflate(R.menu.down, menu);
        return true;
    }

    //下载操作
    public void downLoad(View v) {

        // 改变变量值：
        MainActivity.flag = true;
        MainActivity.pb_count = 0;

        path = et_url.getText().toString();
        String threadNum_et = et_num.getText().toString();
        if (TextUtils.isEmpty(path) || TextUtils.isEmpty(threadNum_et)) {
            Toast.makeText(this, "不能为空", Toast.LENGTH_LONG).show();
            return;
        }

        Toast.makeText(this, "url:" + path + "--" + threadNum_et,
                Toast.LENGTH_LONG).show();

        // 转换成数字
        threadNum = Integer.valueOf(threadNum_et);

        new Thread(new Runnable() {

            @Override
            public void run() {
                try {
                    // 创建出URL对象
                    URL url = new URL(path);
                    // 创建出 HttpURLConnection对象
                    HttpURLConnection httpURLConnection = (HttpURLConnection) url
                            .openConnection();

补充：移动开发 , Android ,