1.文件下载步骤：
1.1创建一个HttpURLConnection对象：HttpURLConnection urlConn = (HttpURLConnection)url.openConnection();
1.2获得一个InputStream对象：urlConn.getInputStream()
1.3访问网络权限:android:permission.INTERNET
2代码：
2.1 DownloadActivity：
package com.van.Download;
import com.van.utils.HttpDownloader;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class DownloadActivityextends Activity
{
privateButton downloadTextButton;
privateButton downloadMp3Button;
@Override
publicvoid onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
downloadTextButton = (Button) findViewById(R.id.downloadText);
downloadTextButton.setOnClickListener(listener);
downloadMp3Button = (Button) findViewById(R.id.downloadMp3);
downloadMp3Button.setOnClickListener(listener);
}
OnClickListenerlistener = new OnClickListener()
{
@Override
public voidonClick(View arg0)
{
switch (arg0.getId())
{
case R.id.downloadText:
HttpDownloader httpDownloader1 =new HttpDownloader();
String lrc1 = httpDownloader1.download("http://wenku.baidu.com/submit");
System.out.println(lrc1);
break;
caseR.id.downloadMp3:
HttpDownloader httpDownloader =new HttpDownloader();
String lrc = httpDownloader.download("");
System.out.println(lrc);
break;
}
}
};
}
2.2 HttpDownloader：
package com.van.utils;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class HttpDownloader
{
privateURL url = null;
publicString download(String urlStr)
{
StringBuffer sb =new StringBuffer();
String line =null;
BufferedReader buffer =null;
try
{
// 创建一个URL对象
url = new URL(urlStr);
// 创建一个Http连接
HttpURLConnection urlConn = (HttpURLConnection)url.openConnection();
// 使用IO流读取数据
buffer =new BufferedReader(newInputStreamReader(urlConn.getInputStream()));
while ((line = buffer.readLine()) != null)
{
sb.append(line);
}
}
catch (MalformedURLException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
try
{
buffer.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
return sb.toString();
}
publicint downFile(String urlStr, String path, String fileName)
{
InputStream inputStream =null;
try
{
FileUtils fileUtils =new FileUtils();
if (fileUtils.isFileExist(path + fileName))
{
return 1;
}
else
{
inputStream = getInputStreamFromFUrl(urlStr);
}
File resultFile = fileUtils.write2SDFromInput(path, fileName, inputStream);
if (resultFile == null)
{
return -1;
}
}
catch (IOException e)
{
e.printStackTrace();
return -1;
}finally{
try
{
inputStream.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
return 0;
}
publicInputStream getInputStreamFromFUrl(String urlStr)throws IOException
{
url = new URL(urlStr);
HttpURLConnection urlConn = (HttpURLConnection)url.openConnection();
InputStream inputStream = urlConn.getInputStream();
return inputStream;
}
}
2.3 FileUtils：
package com.van.utils;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.os.Environment;
public class FileUtils
{
privateString SDPATH;
publicString getSDPATH()
{
return SDPATH;
}
publicFileUtils()
{
// 的到当前外部存储设备的目录
SDPATH = Environment.getExternalStorageDirectory() +"/";
}
publicFile creatSDFile(String fileName) throwsIOException
{
File file =new File(SDPATH + fileName);
file.createNewFile();
return file;
}
publicFile creatSDDir(String dirName)
{
File dir =new File(SDPATH + dirName);
dir.mkdir();
return dir;
}
publicboolean isFileExist(String fileName)
{
File file =new File(SDPATH + fileName);
return file.exists();
}
publicFile write2SDFromInput(String path, String fileName, InputStream inputSteam)
{
File file =null;
OutputStream output =null;
try
{
creatSDDir(path);
File f = creatSDFile(path + fileName);
output =newFileOutputStream(f);
byte buffer[] = new byte[4 * 1024];
while ((inputSteam.read(buffer)) != -1)
{
output.write(buffer);
}
System.out.println(path);
file =new File(path);
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
try
{
output.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
return file;
}
}
2.4 AndroidManifest.xml:
<?xmlversion="1.0"encoding="utf-8"?>
<manifestxmlns:android="http://schemas.android.com/apk/res/android"
package="com.van.Download"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="8"/>
<application android:icon="@drawable/icon"android:label="@string/app_name">
<activity android:name=".DownloadActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>
<uses-permissionandroid:name="android.permission.INTERNET"/>[jhoo1]
<uses-permissionandroid:name="android.permission.WRITE_EXTERNAL_STORAGE"/>[jhoo2]
</manifest>
