安卓中使用HTTP从网络下载文件到SD卡程序

程序实现在安卓中下载在PC端tomcat中的文件并将其存放到SD卡当中并显示。程序主要代码：

//HttpDownLoad类，该类提供了通过url得到一个http连接的方法和一个从指定url得到一个图片的方法，程序代码如下

package yingxian.HttpDownLoad;

import java.io.IOException;

import java.io.InputStream;

import java.net.HttpURLConnection;

import java.net.MalformedURLException;

import java.net.URL;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

public class HttpDownLoad {

protected String urlStr = null;

public HttpDownLoad()  {}

public HttpDownLoad(String downUrlStr)  {

this.urlStr = downUrlStr;

}

public String getUrlStr()  {

return this.urlStr;

}

public void setUrlStr(String url)  {

this.urlStr = url;

}

public HttpURLConnection getHttpConn()  {

URL myURL = null;

HttpURLConnection httpUrlConn = null;

try {

  myURL = new URL(urlStr);

}

catch(MalformedURLException mfex)  {

mfex.printStackTrace();

}

try{

  httpUrlConn = (HttpURLConnection)myURL.openConnection();

}

catch(IOException ioex)  {

ioex.printStackTrace();

}

return httpUrlConn;

}

public Bitmap getImageBitmap()  {

Bitmap bitmap = null;

try  {

HttpURLConnection urlConn = getHttpConn();

urlConn.setDoInput(true);

urlConn.connect();

InputStream is = urlConn.getInputStream();

bitmap = BitmapFactory.decodeStream(is);

is.close();

}

catch(IOException ex)  {

ex.printStackTrace();

}

return bitmap;

}

}

 
//FileToSDCard类，该类实现将输入流中的文件按照指定的文件名存放到SD卡指定的路径中，如果文件已存在则先执行删除然后新建，程序代码如下：

package yingxian.FileUtils;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import android.os.Environment;

public class FileToSDCard { 

   protected String fileName = null;

   protected String savePath = null;

   protected InputStream is = null;

   public FileToSDCard()  {  }

   public FileToSDCard(String fileNameTemp,String saveDir,InputStream isTemp)  {

  this.fileName = fileNameTemp;

  this.savePath = getSDCardPath() + File.separator + saveDir + File.separator;

  this.is = isTemp;

   }

   public String getFileName()  {

  return this.fileName;

   }

   public void setFileName(String strTemp)  {

  this.fileName = strTemp;

   }

   

   public String getSavePath()  {

  return this.savePath;

   }

   public void setSavePath(String saveDir)  {

  this.savePath = getSDCardPath() + File.separator + saveDir + File.separator;

   }

   public void setIS(InputStream isTemp)  {

  this.is = isTemp;

   }

   public InputStream getIS()  {

  return this.is;

   }

   

   public boolean isSDCardExits()  {

  if(Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState()))  {

  return true;

  }

  else {

  return false;

  }

   }

   

   public boolean isFileExits(String nameStr)  {

  File file = new File(nameStr);

  if(file.exists())  {

  return true;

  }

  else {

  return false;

  }

   }

   

   public String getFileNameFromURL(String URLStr)  {

  String fileNameStr = URLStr.substring(URLStr.lastIndexOf(File.separator) + 1);

  return fileNameStr;

   }

   

   public String getSDCardPath()  {

  String sdCardPath = Environment.getExternalStorageDirectory().getAbsolutePath();

  return sdCardPath;

   }

   

   /**创建目录文件的函数，当返回值1--文件已存在；0--文件创建成功；-1--文件创建失败*/

   public int createDir()  {

  if(isFileExits(savePath))  {

  return 1;

  }

  else {

  File fileDir =  new File(savePath);

  if(fileDir.mkdir())  {

  return 0;

  }

  else {

  return -1;

  }

  }

   }

   

   public boolean deleteFile()  {

 File file = new File((this.savePath + this.fileName));

 return file.delete();

   }

   

   public File createNewFile() throws IOException  {

  if(this.deleteFile())  {

  System.out.println("Delete old file...");

      return this.createSDFile();

  }

  else {

  return null;

  }

   }

   

   public File createSDFile() throws IOException {

   File file = new File((savePath + fileName));

if(file.createNewFile())  {

System.out.println("Create new file...");

  return file;

}else {

  return null;

}

   }

   public File writeToSDFromInput()  {

  File file = null;

  FileOutputStream output = null;

  int readCount = 0;

  try {

  if(!isSDCardExits())  {

  System.out.println("SDcard is not exits***");

  return null;

  }

  if(this.createDir() == -1)  {

  System.out.println("dir create fail***");

  return null;

  }

  if(!isFileExits(savePath + fileName))  {

  System.out.println("create file...");

  file = createSDFile();

  }

  else {

  System.out.print("create file exits***\n");

  file = this.createNewFile();

  }

  output = new FileOutputStream(file);

  byte[] buffer = new byte[1024];

  while((readCount = is.read(buffer)) != -1)  {

  output.write(buffer,0,readCount);

  }

  output.flush();

}

  catch(IOException ioex)  {

  ioex.printStackTrace();

  }

  catch(Exception ex)  {

  ex.printStackTrace();

  }

  finally  {

  try {

  if(output != null)  {

     output.close();

  }

  if(is != null)  {

  is.close();

  }

  }

  catch(Exception ex)  {

  ex.printStackTrace();

  }

  }

  return file;

   }

}

// MainActivity 中有三个按钮和一个imageView，按钮my_Btn_Update 实现从网络下载图片并直接将其显示而不存到SD卡。按钮my_Btn_Down 将网络上的图片下载后存到SD卡上。按钮my_Btn_Show 实现将SD卡上的图片显示到imageView中。程序代码如下：

package yingxian.httpdownloadstudy;

import java.io.IOException;

import java.net.HttpURLConnection;

import yingxian.FileUtils.FileToSDCard;

import yingxian.HttpDownLoad.HttpDownLoad;

import android.os.Bundle;

import android.os.StrictMode;

import android.app.Activity;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.ImageView;

public class MainActivity extends Activity {

private ImageView my_IV_Photo = null;

private Button my_Btn_Update = null;

private Button my_Btn_Down = null;

private Button my_Btn_Show = null;

private FileToSDCard writeToSD = null;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());

StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder().detectLeakedSqlLiteObjects().detectLeakedClosableObjects().penaltyLog().penaltyDeath().build());

this.initComponent();

}

@Override

protected void onStop() {

super.onStop();

MainActivity.this.finish();

}

private void initComponent()  {

this.my_IV_Photo = (ImageView)findViewById(R.id.myIV01);

this.my_Btn_Update = (Button)findViewById(R.id.myBtn01);

this.my_Btn_Down = (Button)findViewById(R.id.myBtn02);

this.my_Btn_Show = (Button)findViewById(R.id.myBtn03);

this.my_Btn_Update.setOnClickListener(new OnClickListener() {

@Override

public void onClick(View v) {

HttpDownLoad httpDown = new HttpDownLoad("http://192.168.43.105:8080/MP3/jbfc.png");

my_IV_Photo.setImageBitmap(httpDown.getImageBitmap());

}

});

this.my_Btn_Down.setOnClickListener(new OnClickListener() {

@Override

public void onClick(View v) {

try  {

  HttpDownLoad httpDown = new HttpDownLoad("http://192.168.43.105:8080/MP3/sckxc.png");

  HttpURLConnection httpURLConn = httpDown.getHttpConn();

  httpURLConn.connect();

  writeToSD = new FileToSDCard("yxrs.jpg", "testDir", httpURLConn.getInputStream());

  System.out.print("filename="+ writeToSD.getFileName() + "savepath="+ writeToSD.getSavePath()+"\n");

  writeToSD.writeToSDFromInput();

}

catch(IOException ioex)  {

ioex.printStackTrace();

}

catch (Exception ex) {

ex.printStackTrace();

}

}

});

this.my_Btn_Show.setOnClickListener(new OnClickListener() {

@Override

public void onClick(View v) {

String myJPGPath = "/mnt/local/testDir/yxrs.jpg";

BitmapFactory.Options option = new BitmapFactory.Options();

option.inSampleSize = 1;

Bitmap bm = BitmapFactory.decodeFile(myJPGPath, option);

my_IV_Photo.setImageBitmap(bm);

}

});

}

}

 

 注意：在程序manifest中需要添加程序SD卡读写权利和使用网络的权利