Download(下载) 项目 详解
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本文地址: http://blog.csdn.net/caroline_wendy/article/details/22280461
环境: Android 0.5.2 + gradle 1.11 + kindle fire
Download, 下载项目, 从Internet上下载资源, 并存入本地SD卡.
点击Download按钮, 下载图片, 然后显示下载内容, 可以点击查看.
Download的具体设计:
1. 修改activity_main.xml
位置: res->layout->activity_main.xml
添加一个按钮(Button), 使"hello_world"在其下方, 使用layout_below属性;
2. 修改AndroidManifest.xml
位置: main->AndroidManifest.xml
需要
INTERNET, 连接互联网的权限;
WRITE_EXTERNAL_STORAGE, 写入存储器的权限;
3. 修改MainActivity.java
位置: java->package->MainActivity.java
package mzx.spike.download.app; import android.app.Activity; import android.app.DownloadManager; import android.content.Context; import android.content.Intent; import android.database.Cursor; import android.net.Uri; import android.os.Bundle; import android.util.Log; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.Button; import android.widget.Toast; import java.io.IOException; import java.net.MalformedURLException; import java.net.URL; import java.net.URLConnection; public class MainActivity extends Activity { private static final String TAG = "Download"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button buttonDownload = (Button)findViewById(R.id.download_button); buttonDownload.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { myDownload(); } }); } @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; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } private void myDownload() { String serviceString = Context.DOWNLOAD_SERVICE; DownloadManager downloadManager; downloadManager = (DownloadManager) getSystemService(serviceString); Uri uri = Uri.parse("http://bizhi.zhuoku.com/2014/03/26/TAHITI/TAHITI02.jpg"); DownloadManager.Request request = new DownloadManager.Request(uri); request.setDestinationInExternalPublicDir("/Download", "file.jpg"); request.setVisibleInDownloadsUi(true); long reference = downloadManager.enqueue(request); Log.d(TAG, "Download Reference: " + reference); Cursor c = downloadManager.query(new DownloadManager.Query().setFilterById(reference)); if (c == null) { Toast.makeText(this, "Download not found!", Toast.LENGTH_LONG).show(); } else { c.moveToFirst(); Log.d(getClass().getName(), "Column_id : " + c.getLong(c.getColumnIndex(DownloadManager.COLUMN_ID))); Log.d(getClass().getName(), "Column_bytes_downloaded so far : " + c.getLong(c.getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR))); Log.d(getClass().getName(), "Column last modified timestamp : " + c.getLong(c.getColumnIndex(DownloadManager.COLUMN_LAST_MODIFIED_TIMESTAMP))); Log.d(getClass().getName(), "Column local uri : " + c.getString(c.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI))); Log.d(getClass().getName(), "Column statue : " + c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS))); Log.d(getClass().getName(), "Column reason : " + c.getInt(c.getColumnIndex(DownloadManager.COLUMN_REASON))); Toast.makeText(this, statusMessage(c), Toast.LENGTH_LONG).show(); } startActivity(new Intent(DownloadManager.ACTION_VIEW_DOWNLOADS)); } private String statusMessage(Cursor c){ switch(c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS))){ case DownloadManager.STATUS_FAILED: return "Download failed"; case DownloadManager.STATUS_PAUSED: return "Download paused"; case DownloadManager.STATUS_PENDING: return "Download pending"; case DownloadManager.STATUS_RUNNING: return "Download in progress!"; case DownloadManager.STATUS_SUCCESSFUL: return "Download finished"; default: return "Unknown Information"; } } } 详解:1. 在创建界面中, 填写按钮(button)的点击事件(setOnClickListener), 触发下载方法(myDownload);
2. DownloadManager 获取下载的服务(Context.DOWNLOAD_SERVICE);
3. 设置下载的链接(uri), 设置存储位置(setDestinationInExternalPublicDir), 显示下载用户接口(setVisibleInDownloadsUi);
4. 放置下载队列, 开始下载, downloadManager.enqueue(request);
5. 通过游标获取下载信息, downloadManager.query();
6. 输出相应的下载信息(COLUMN_*), 和下载状态(STATUS_*);
7. 显示下载视图(DownloadManager.ACTION_VIEW_DOWNLOADS);
注意:
存储位置(setDestinationInExternalPublicDir), 需要提前设置, 否则无法查看文件, 存储至content位置;
4. 运行程序
下载地址: http://download.csdn.net/detail/u012515223/7106567
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