編輯:關於Android編程
通過URL來獲取網絡資源並下載資源簡單實例:
package com.android.xiong.urltest; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.MalformedURLException; import java.net.URL; import android.app.Activity; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.Menu; import android.widget.ImageView; public class MainActivity extends Activity { ImageView show; Bitmap bitmap; Handler handler = new Handler() { @Override public void handleMessage(Message msg) { if (msg.what == 0x123) { // 使用ImageView顯示該圖片 show.setImageBitmap(bitmap); } } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); show = (ImageView) findViewById(R.id.show); new Thread() { @Override public void run() { // 定義一個URL對象 URL url; try { url = new URL( "http://img1.gtimg.com/news/pics/hv1/37/195/1468/95506462.jpg"); // 打開該URL的資源輸入流 InputStream is = url.openStream(); // 從InputStream中解析出圖片 bitmap = BitmapFactory.decodeStream(is); // 發送消息 handler.sendEmptyMessage(0x123); is.close(); // 再次打開RL對應的資源輸入流 is = url.openStream(); // 打開手機文件對應的輸出流 OutputStream os = openFileOutput("KEQIANG.JPG", MODE_APPEND); byte[] buff = new byte[1024]; int hasRead = 0; // 將URL資源下載到本地 while ((hasRead = is.read(buff)) > 0) { os.write(buff, 0, hasRead); } is.close(); os.close(); } catch (MalformedURLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }.start(); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } }
<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" android:orientation="vertical" tools:context=".MainActivity" > <ImageView android:id="@+id/show" android:layout_width="match_parent" android:layout_height="match_parent" android:contentDescription="@string/hello_world"/> </LinearLayout>
網絡資源多線程下載:
package com.example.threaddown; import java.util.Timer; import java.util.TimerTask; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.Menu; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.ProgressBar; public class MainActivity extends Activity { EditText url; EditText target; Button downBn; ProgressBar bar; DownUtil downUtil; private int mDownStatus; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // 獲取程序界面中的三個界面控制 url = (EditText) findViewById(R.id.url); target = (EditText) findViewById(R.id.target); downBn = (Button) findViewById(R.id.downBn); bar = (ProgressBar) findViewById(R.id.br); // 創建一個Handler對象 final Handler handler = new Handler() { @Override public void handleMessage(Message msg) { if (msg.what == 0x123) { bar.setProgress(mDownStatus); } } }; downBn.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { // 初始化DownUtil對象 downUtil = new DownUtil(url.getText().toString(), target .getText().toString(), 6); new Thread() { @Override public void run() { try { // 開始下載 downUtil.download(); } catch (Exception e) { e.printStackTrace(); } // 定義每秒調度獲取一次系統的完成進度 final Timer timer = new Timer(); timer.schedule(new TimerTask() { @Override public void run() { // 獲取下載任務的完成比例 double completeRate = downUtil .getCompleteRate(); mDownStatus = (int) (completeRate * 1000); // 發送消息通知屆滿更新的進度條 handler.sendEmptyMessage(0x123); // 下載完成之後取消任務進度 if (mDownStatus >= 100) { timer.cancel(); } } }, 0, 1000); } }.start(); } }); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } }
package com.example.threaddown; import java.io.IOException; import java.io.InputStream; import java.io.RandomAccessFile; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; public class DownUtil { // 定義下載資源的路徑 private String path; // 指定所下載的文件的保存位置 private String targetFile; // 定義需要使用多少線程下載資源 private int threadNum; // 定義下載的線程對象 private DownThread[] threads; // 定義下載的文件總大小 private int fileSize; public DownUtil(String path, String targetFile, int threadNum) { this.path = path; this.targetFile = targetFile; this.threadNum = threadNum; } public void download() throws IOException { URL url = new URL(path); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setConnectTimeout(5000); conn.setRequestMethod("GET"); conn.setRequestProperty("Accept", "*/*"); conn.setRequestProperty("Accept-Language", "zh-CN"); conn.setRequestProperty("Charset", "UTF-8"); conn.setRequestProperty("Connection", "Keep-Alive"); // 得到文件的大小 fileSize = conn.getContentLength(); conn.disconnect(); int currentPartsSize = fileSize / threadNum + 1; RandomAccessFile file = new RandomAccessFile(targetFile, "rw"); // 設置本地文件的大小 file.setLength(fileSize); file.close(); for (int i = 0; i < threadNum; i++) { // 計算每條線程的下載位置 int startPos = i * currentPartsSize; // 每個線程使用一個RandomAccessFile進行下載 RandomAccessFile current = new RandomAccessFile(targetFile, "rw"); // 定義該線程的下載位置 current.seek(startPos); // 創建下載線程 threads[i] = new DownThread(startPos, currentPartsSize, current); // 啟動線程下載 threads[i].start(); } } // 獲取下載的完成百分比 public double getCompleteRate() { // 統計多條線程已經下載的總大小 int sumSize = 0; for (int i = 0; i < threadNum; i++) { sumSize += threads[i].length; } return sumSize * 1.0 / fileSize; } private class DownThread extends Thread { // 定義當前線程下載的位置 private int startPos; // 定義當前線程下載文件的大小 private int currentPartsSize; // 當前線程下載的文件塊 private RandomAccessFile currentPart; // 定義該線程已下載的字節數 private int length; public DownThread(int startPos, int currentPartsSize, RandomAccessFile currentPart) { this.startPos = startPos; this.currentPart = currentPart; this.currentPartsSize = currentPartsSize; } @Override public void run() { try { URL url = new URL(path); HttpURLConnection conn = (HttpURLConnection) url .openConnection(); conn.setConnectTimeout(5000); conn.setRequestMethod("GET"); conn.setRequestProperty("Accept", "*/*"); conn.setRequestProperty("Accept-Language", "zh-CN"); conn.setRequestProperty("Charset", "UTF-8"); conn.setRequestProperty("Connection", "Keep-Alive"); InputStream in = conn.getInputStream(); in.skip(startPos); int hasRead = 0; byte[] buffer = new byte[1024]; // 讀取網絡數據,並寫入本地文件 while (length < currentPartsSize && (hasRead = in.read(buffer)) > 0) { currentPart.write(buffer, 0, hasRead); // 累計該線程下載的總大小 length += hasRead; } currentPart.close(); in.close(); } catch (Exception e) { e.printStackTrace(); } } } }
<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" android:orientation="vertical" tools:context=".MainActivity" > <EditText android:id="@+id/url" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="http://ksoap2-android.googlecode.com/svn/m2-repo/com/google/code/ksoap2-android/ksoap2-android-assembly/3.1.0/ksoap2-android-assembly-3.1.0-jar-with-dependencies.jar" /> <EditText android:id="@+id/target" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="/mnt/sdcard/"/> <Button android:id="@+id/downBn" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="down" /> <ProgressBar android:id="@+id/br" android:layout_width="match_parent" android:layout_height="wrap_content" /> </LinearLayout>
<!-- 在SD卡中創建與刪除文件的權限 --> <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" /> <!-- 在SD開中寫入數據的權限 --> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <!-- 訪問網路的權限 --> <uses-permission android:name="android.permission.INTERNET" />
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