Android 下載文件及寫入SD卡,實例代碼
Main.xml代碼
<?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="下載文本文件"
/>
<Button
android:id="@+id/downloadMp3"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="下載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" />
<!-- 訪問網絡和操作SD卡 加入的兩個權限配置-->
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
</manifest>
下載助手類httpdownloader 代碼
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;
/**
* 根據URL下載文件,前提是這個文件當中的內容是文本,函數的返回值就是文本當中的內容
* 1.創建一個URL對象
* 2.通過URL對象,創建一個HttpURLConnection對象
* 3.得到InputStream
* 4.從InputStream當中讀取數據
* @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:文件下載出錯
* 0:文件下載成功
* 1:文件已經存在
*/
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;
}
/**
* 根據URL得到輸入流
* @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;
}
}
文件操作類fileutils 代碼
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;
public class FileUtils {
private String SDPATH;
private int FILESIZE = 4 * 1024;
public String getSDPATH(){
return SDPATH;
}
public FileUtils(){
//得到當前外部存儲設備的目錄( /SDCARD )
SDPATH = Environment.getExternalStorageDirectory() + "/";
}
/**
* 在SD卡上創建文件
* @param fileName
* @return
* @throws IOException
*/
public File createSDFile(String fileName) throws IOException{
File file = new File(SDPATH + fileName);
file.createNewFile();
return file;
}
/**
* 在SD卡上創建目錄
* @param dirName
* @return
*/
public File createSDDir(String dirName){
File dir = new File(SDPATH + dirName);
dir.mkdir();
return dir;
}
/**
* 判斷SD卡上的文件夾是否存在
* @param fileName
* @return
*/
public boolean isFileExist(String fileName){
File file = new File(SDPATH + fileName);
return file.exists();
}
/**
* 將一個InputStream裡面的數據寫入到SD卡中
* @param path
* @param fileName
* @param input
* @return
*/
public File write2SDFromInput(String path,String fileName,InputStream input){
File file = null;
OutputStream output = null;
try {
createSDDir(path);
file = createSDFile(path + fileName);
output = new FileOutputStream(file);
byte[] buffer = new byte[FILESIZE];
/*真機測試，這段可能有問題，請采用下面網友提供的
while((input.read(buffer)) != -1){
output.write(buffer);
}
*/
/* 網友提供 begin */
int length;
while((length=(input.read(buffer))) >0){
output.write(buffer,0,length);
}
/* 網友提供 end */
output.flush();
}
catch (Exception e) {
e.printStackTrace();
}
finally{
try {
output.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return file;
}
}
更多詳情見請繼續閱讀下一頁的精彩內容： http://www.linuxidc.com/Linux/2014-04/100541p2.htm