Android 下载文件及写入SD卡,实例代码
Main.xml代码
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<Button
android:id="@+id/downloadTxt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="下载文本文件"
/>
<Button
android:id="@+id/downloadMp3"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="下载MP3文件"
/>
</LinearLayout>
Androidmanifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.learning.example"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".Download"
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-sdk android:minSdkVersion="8" />
<!-- 访问网络和操作SD卡 加入的两个权限配置-->
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
</manifest>
下载助手类httpdownloader 代码
package com.learning.example.util;
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 {
private URL url = null;
/**
* 根据URL下载文件,前提是这个文件当中的内容是文本,函数的返回值就是文本当中的内容
* 1.创建一个URL对象
* 2.通过URL对象,创建一个HttpURLConnection对象
* 3.得到InputStream
* 4.从InputStream当中读取数据
* @param urlStr
* @return
*/
public String download(String urlStr){
StringBuffer sb = new StringBuffer();
String line = null;
BufferedReader buffer = null;
try {
url = new URL(urlStr);
HttpURLConnection urlConn = (HttpURLConnection)url.openConnection();
buffer = new BufferedReader(new InputStreamReader(urlConn.getInputStream()));
while( (line = buffer.readLine()) != null){
sb.append(line);
}
}
catch (Exception e) {
e.printStackTrace();
}
finally{
try {
buffer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
/**
*
* @param urlStr
* @param path
* @param fileName
* @return
* -1:文件下载出错
* 0:文件下载成功
* 1:文件已经存在
*/
public int downFile(String urlStr, String path, String fileName){
InputStream inputStream = null;
try {
FileUtils fileUtils = new FileUtils();
if(fileUtils.isFileExist(path + fileName)){
return 1;
} else {
inputStream = getInputStreamFromURL(urlStr);
File resultFile = fileUtils.write2SDFromInput(path, fileName, inputStream);
if(resultFile == null){
return -1;
}
}
}
catch (Exception e) {
e.printStackTrace();
return -1;
}
finally{
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return 0;
}
/**
* 根据URL得到输入流
* @param urlStr
* @return
*/
public InputStream getInputStreamFromURL(String urlStr) {
HttpURLConnection urlConn = null;
InputStream inputStream = null;
try {
url = new URL(urlStr);
urlConn = (HttpURLConnection)url.openConnection();
inputStream = urlConn.getInputStream();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return inputStream;
}
}
文件操作类fileutils 代码
package com.learning.example.util;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.os.Environment;