android下载实例
1、Androidmanifest.xml的文件一定要加上权限
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="chester.download"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="4" />
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:label="@string/app_name"
android:name=".DownLoadexample" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
2、activity代码如下：
package chester.download;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
import chester.utils.HttpDownloader;
/**
*
*@title DownLoadexample
*@describe TODO 使用http协议下载txt文件和mp3文件
*@author Chester
*@date 2011-11-4
*@version V1.0
*/
public class DownLoadexample extends Activity {
private Button downloadtxtButton =null;
private Button downloadfilebuButton=null;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
/**
* 得到两个button控件对象
*/
downloadtxtButton=(Button)findViewById(R.id.downloadtxtbutton);
downloadfilebuButton=(Button)findViewById(R.id.downloadmp3button);
downloadtxtButton.setOnClickListener(new TxtButtonListener());
downloadfilebuButton.setOnClickListener(new FileButtonListener());
}
/**
*
*@title TxtButtonLinstener
*@describe TODO 使用内部类实现TxtButtonLinstener监听器
*@author Chester
*@date 2011-11-4
*@version V1.0
*/
class TxtButtonListener implements OnClickListener{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
//HttpDownloader 是自己写的类，封装起来，以后使用方便
HttpDownloader httpDownloader=new HttpDownloader();
//根据URL得到文件
String str=httpDownloader.downloadfile("http://3g.sina.com.cn/");
//得到的是sina的wap包wml语言
System.out.println(str);
Toast.makeText(DownLoadexample.this, str, Toast.LENGTH_LONG).show();
}
}
/**
*
*@title FileButtonListener
*@describe TODO 使用内部类实现Mp3ButtonLinstener监听器
*@author Chester
*@date 2011-11-4
*@version V1.0
*/
class FileButtonListener implements OnClickListener{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
HttpDownloader httpDownloader=new HttpDownloader();
int mp3int=httpDownloader.downloadFile("http://u.androidgame-store.com/android1/new/game1/24/110424/kwplayer_1.apk", "mymp3", "chester.apk");
Toast.makeText(DownLoadexample.this, mp3int+"/", Toast.LENGTH_SHORT).show();
}
}
}
3、HttpDownloader类的代码
package chester.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;
/**
*
*@title HttpDownloader
*@describe TODO 根据URL下载文件类
* 1、首先创建一个URL对象
* 2、根据URL对象，创建一个HttpURLConnection对象
* 3、得到IputStream
* 4、从IputStream当中读取数据
*@author Chester
*@date 2011-11-4
*@version V1.0
*/
public class HttpDownloader {
private URL url=null;
/**
*
*@title download
*@describe TODO 根据url下载文件，前提是这个文件当中的内容是文本，函数返回值是这个文件的文本内容
*@param @param urlsString
*@param @return
*@throws
*/
public String downloadfile(String urlString) {
StringBuffer stringBuffer=new StringBuffer();
String line=null;
BufferedReader bufferedReader=null;
try {
//创建一个URL对象
url=new URL(urlString);
//创建一个http连接
HttpURLConnection urlConnection=(HttpURLConnection)url.openConnection();
//使用IO流读取数据
bufferedReader=new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
while ((line=bufferedReader.readLine())!=null) {
stringBuffer.append(line);
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally{
//下面还有加上try，有可能关不了
try {
bufferedReader.close();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
return stringBuffer.toString();
}
/**
*
*@title downFile
*@describe TODO 该函数可以下载任意文件。返回-1：代表下载文件出错，0：代表下载文件成功，1：代表文件已经存在
*@param @param urString 网络地址
*@param @param path 存放路径
*@param @param fileName 存放文件名
*@param @return
*@throws
*/
public int downloadFile(String urlStr,String path,String fileName) {
InputStream inputStream=null;
try {
FileUtils fileUtils=new FileUtils();
//判断文件是否存在，存在则返回1 path+"/"+fileName这个参数一定要写对。
if (fileUtils.isFileExist(path+"/"+fileName)) {
return 1;
}else {
//根据URL得到输入流
inputStream=getInputStreamFromUrl(urlStr);
File resultFile=fileUtils.write2SDFromInput(path, fileName, inputStream);
if (resultFile==null) {
//文件是空的就返回-1
return -1;
}
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally{
try {
inputStream.close();
} catch (Exception e2) {
// TODO: handle exception
e2.printStackTrace();
}
}
return 0;
}
/**
*
*@title getInputStreamFromUrl
*@describe TODO 根据URL得到输入流
*@param @param urlstr
*@param @return
*@param @throws MalformedURLException
*@param @throws IOException
*@throws
*/
public InputStream getInputStreamFromUrl(String urlstr) throws MalformedURLException,IOException{
url=new URL(urlstr);
HttpURLConnection httpURLConnection=(HttpURLConnection)url.openConnection();
InputStream inputStream=httpURLConnection.getInputStream();
return inputStream;
}
}
4、FileUtils代码
package chester.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;
/**
*
*@title FileUtils
*@describe TODO
*@author Chester
*@date 2011-11-4
*@version V1.0
*/
public class FileUtils {
//路径
private String SDPATH;
/**
*
*@title getSDPATH
*@describe TODO
*@param @return
*@throws
*/
public String getSDPATH() {
return SDPATH;
}
/**
*
*@Title
*@describe TODO 构造函数，得到SD当前目录
*@param
*/
public FileUtils(){
//得到当前外部存储设备的目录
// /SDCARD
SDPATH=Environment.getExternalStorageDirectory()+"/";
}
/**
*
*@title createSDFile
*@describe TODO 在SD卡中创建文件
*@param @param fileName
*@param @return
*@param @throws IOException
*@throws
*/
public File createSDFile(String fileName) throws IOException{
File file = new File(SDPATH + fileName);
file.createNewFile();
return file;
}
/**
*
*@title createSDDir
*@describe TODO 在SD卡上创建目录
*@param @param fileName
*@param @return
*@throws
*/
public File createSDDir(String fileName) {
File dir =new File(SDPATH+fileName);
dir.mkdir();
return dir;
}
/**
*
*@title isFileExist
*@describe TODO 判定SD卡中的文件夹是否存在
*@param @param fileName
*@param @return
*@throws
*/
public boolean isFileExist(String fileName) {
File file = new File(SDPATH + fileName);
return file.exists();
}
/**
*
*@title write2SDFromInput
*@describe TODO 将一个inputstream的数据写入到SD卡中
*@param @param path
*@param @param fileName
*@param @param inputStream
*@param @return
*@throws
*/
public File write2SDFromInput(String path,String fileName,InputStream inputStream) {
File file=null;
OutputStream outputStream=null;
try {
//创建文件夹
createSDDir(path);
//在path文件夹下创建文件,+"/"这个必须加
file=createSDFile(path+"/"+fileName);
outputStream=new FileOutputStream(file);
//每一个以4K的速度写入
byte buffer[]=new byte[4*1024];
while ((inputStream.read(buffer))!=-1) {
outputStream.write(buffer);
}
//清空一下缓存
outputStream.flush();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally{
try {
//把打开的流关闭掉
outputStream.close();
} catch (Exception e2) {
// TODO: handle exception
e2.printStackTrace();
}
}
return file;
}
}
