进度条是通过填充器导入pb.xml文件来显示的

java代码参照java栏目的多线程下载代码解释

package com.itheima.mutilethread;import java.io.BufferedReader;import java.io.File;import java.io.FileInputStream;import java.io.InputStream;import java.io.InputStreamReader;import java.io.RandomAccessFile;import java.net.HttpURLConnection;import java.net.URL;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.os.Bundle;import android.os.Environment;import android.os.Handler;import android.os.Message;import android.text.TextUtils;import android.view.View;import android.widget.EditText;import android.widget.LinearLayout;import android.widget.ProgressBar;import android.widget.Toast;public class MainActivity extends Activity {	protected static final int DOWNLOAD_ERROR = 1;	private static final int THREAD_ERROR = 2;	public static final int DWONLOAD_FINISH = 3;	private EditText et_path;	private EditText et_count;	/**	 * 存放进度条的布局	 */	private LinearLayout ll_container;		/**	 * 进度条的集合	 */	private List
    
      pbs;		/**	 * android下的消息处理器，在主线程创建，才可以更新ui	 */	private Handler handler = new Handler(){		public void handleMessage(Message msg) {			switch (msg.what) {			case DOWNLOAD_ERROR:				Toast.makeText(getApplicationContext(), "下载失败", 0).show();				break;			case THREAD_ERROR:				Toast.makeText(getApplicationContext(), "下载失败,请重试", 0).show();				break;			case DWONLOAD_FINISH:				Toast.makeText(getApplicationContext(), "下载完成", 0).show();				break;			}		};	};		/**	 * 线程的数量	 */	private int threadCount = 3;	/**	 * 每个下载区块的大小	 */	private long blocksize;	/**	 * 正在运行的线程的数量	 */	private  int runningThreadCount;	@Override	protected void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.activity_main);		et_path = (EditText) findViewById(R.id.et_path);		et_count = (EditText) findViewById(R.id.et_count);		ll_container = (LinearLayout) findViewById(R.id.ll_container);	}	/**	 * 下载按钮的点击事件	 * @param view	 */	public void downLoad(View view){		//下载文件的路径		final String path = et_path.getText().toString().trim();		if(TextUtils.isEmpty(path)){			Toast.makeText(this, "对不起下载路径不能为空", 0).show();			return;		}		String count = et_count.getText().toString().trim();		if(TextUtils.isEmpty(path)){			Toast.makeText(this, "对不起,线程数量不能为空", 0).show();			return;		}												threadCount = Integer.parseInt(count);		//清空掉旧的进度条		ll_container.removeAllViews();		//在界面里面添加count个进度条		pbs = new ArrayList
     
      ();		for(int j=0;j
      
        0) {// 判断是否有记录					FileInputStream fis = new FileInputStream(positionFile);					BufferedReader br = new BufferedReader(							new InputStreamReader(fis));					// 获取当前线程上次下载的总大小是多少					String lasttotalstr = br.readLine();					int lastTotal = Integer.valueOf(lasttotalstr);					System.out.println("上次线程" + threadId + "下载的总大小："							+ lastTotal);					startIndex += lastTotal;					total += lastTotal;// 加上上次下载的总大小。					fis.close();					//存数据库。					//_id path threadid total				}				conn.setRequestProperty("Range", "bytes=" + startIndex + "-"						+ endIndex);							conn.setConnectTimeout(5000);				int code = conn.getResponseCode();				System.out.println("code=" + code);				InputStream is = conn.getInputStream();				File file = new File(Environment.getExternalStorageDirectory(),getFileName(path));				RandomAccessFile raf = new RandomAccessFile(file, "rw");				// 指定文件开始写的位置。				raf.seek(startIndex);				System.out.println("第" + threadId + "个线程：写文件的开始位置："						+ String.valueOf(startIndex));				int len = 0;				byte[] buffer = new byte[1024];				while ((len = is.read(buffer)) != -1) {					RandomAccessFile rf = new RandomAccessFile(positionFile,							"rwd");					raf.write(buffer, 0, len);					total += len;					rf.write(String.valueOf(total).getBytes());					rf.close();										//total是当前下载量    更新到进度条中   内部包装好了Message，所以这里是子线程也可以直接更新UI					pbs.get(threadId-1).setProgress(total);														}				is.close();				raf.close();			} catch (Exception e) {				e.printStackTrace();				Message msg = Message.obtain();				msg.what = THREAD_ERROR;				handler.sendMessage(msg);			} finally {				// 只有所有的线程都下载完毕后 才可以删除记录文件。				synchronized (MainActivity.class) {					System.out.println("线程" + threadId + "下载完毕了");					runningThreadCount--;					if (runningThreadCount < 1) {						System.out.println("所有的线程都工作完毕了。删除临时记录的文件");						for (int i = 1; i <= threadCount; i++) {							File f = new File(Environment.getExternalStorageDirectory(),getFileName(path)+ i + ".txt");							System.out.println(f.delete());						}						Message msg = Message.obtain();						msg.what = DWONLOAD_FINISH;						handler.sendMessage(msg);					}				}			}		}	}	//http://192.168.1.100:8080/aa.exe	private String getFileName(String path){		int start = path.lastIndexOf("/")+1;		return path.substring(start);	}	}
      
     
    

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