Android 下载文件及写入SD卡

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代码


<?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;

public class FileUtils {

private String SDPATH;

private int FILESIZE = 4 * 1024;

public String getSDPATH(){

return SDPATH;

}

public FileUtils(){

//得到当前外部存储设备的目录( /SDCARD )

SDPATH = Environment.getExternalStorageDirectory() + "/";

}

/**

* 在SD卡上创建文件

* @param fileName

* @return

* @throws IOException

*/

public File createSDFile(String fileName) throws IOException{

File file = new File(SDPATH + fileName);

file.createNewFile();

return file;

}

/**

* 在SD卡上创建目录

* @param dirName

* @return

*/

public File createSDDir(String dirName){

File dir = new File(SDPATH + dirName);

dir.mkdir();

return dir;

}

/**

* 判断SD卡上的文件夹是否存在

* @param fileName

* @return

*/

public boolean isFileExist(String fileName){

File file = new File(SDPATH + fileName);

return file.exists();

}

/**

* 将一个InputStream里面的数据写入到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];

/*真机测试，这段可能有问题，请采用下面网友提供的

while((input.read(buffer)) != -1){

output.write(buffer);

}

*/

/* 网友提供 begin */

int length;

while((length=(input.read(buffer))) >0){

output.write(buffer,0,length);

}

/* 网友提供 end */

output.flush();

}

catch (Exception e) {

e.printStackTrace();

}

finally{

try {

output.close();

} catch (IOException e) {

e.printStackTrace();

}

}

return file;

}

}

主程序类download 代码


package com.learning.example;

import com.learning.example.util.HttpDownloader;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

public class Download extends Activity {

private Button downlaodTxtButton ;

private Button downlaodMP3Button ;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

downlaodTxtButton = (Button)findViewById(R.id.downloadTxt);

downlaodTxtButton.setOnClickListener(new DownloadTxtListener());

downlaodMP3Button = (Button)findViewById(R.id.downloadMp3);

downlaodMP3Button.setOnClickListener(new DownloadMP3Listener());

}

class DownloadTxtListener implements OnClickListener{

@Override

public void onClick(View v) {

HttpDownloader downloader = new HttpDownloader();

String lrc = downloader.download("http://172.16.11.9:8080/test/1.lrc");

System.out.println(lrc);

}

}

class DownloadMP3Listener implements OnClickListener{

@Override

public void onClick(View v) {

HttpDownloader downloader = new HttpDownloader();

int result = downloader.downFile("http://172.16.11.9:8080/test/1.mp3", "voa/", "1.map3");

System.out.println(result);

}

}

}

Notice:访问网络和操作SD卡 记得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"/>