mars老师[Android开发视频教学].01_18 文件下载 源码

项目截图：

以下是项目各个文件的代码：

=>>Download.java

package mars.download;

import mars.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 Download extends Activity {

/** Called when the activity is first created. */

private Button downloadTxtButton;

private Button downloadMp3Button;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

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

downloadTxtButton.setOnClickListener(new DownloadTxtListener());

downloadMp3Button = (Button)findViewById(R.id.downloadMp3);

downloadMp3Button.setOnClickListener(new DownloadMp3Listener());

}

class DownloadTxtListener implements OnClickListener{

@Override

public void onClick(View v) {

HttpDownloader httpDownloader = new HttpDownloader();

String lrc = httpDownloader.download("http://192.168.1.107:8080/voa1500/a1.lrc");

System.out.println(lrc);

}

}

class DownloadMp3Listener implements OnClickListener{

@Override

public void onClick(View v) {

// TODO Auto-generated method stub

HttpDownloader httpDownloader = new HttpDownloader();

int result = httpDownloader.downFile("http://192.168.1.107:8080/voa1500/a1.mp3", "voa/", "a1.mp3");

System.out.println(result);

}

}

}

=>>HttpDownloader.java

package mars.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 {

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件当中的内容

* 1.创建一个URL对象

* 2.通过URL对象，创建一个HttpURLConnection对象

* 3.得到InputStram

* 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 {

// 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(new InputStreamReader(urlConn

.getInputStream()));

while ((line = buffer.readLine()) != null) {

sb.append(line);

}

} catch (Exception e) {

e.printStackTrace();

} finally {

try {

buffer.close();

} catch (Exception e) {

e.printStackTrace();

}

}

return sb.toString();

}

/**

* 该函数返回整形 -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

*/

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 (Exception e) {

e.printStackTrace();

}

}

return 0;

}

/**

* 根据URL得到输入流

*

* @param urlStr

* @return

* @throws MalformedURLException

* @throws IOException

*/

public InputStream getInputStreamFromUrl(String urlStr)

throws MalformedURLException, IOException {

url = new URL(urlStr);

HttpURLConnection urlConn = (HttpURLConnection) url.openConnection();

InputStream inputStream = urlConn.getInputStream();

return inputStream;

}

}

=>>FileUtils.java

package mars.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 {

private String SDPATH;

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

*

* @throws IOException

*/

public File creatSDFile(String fileName) throws IOException {

File file = new File(SDPATH + fileName);

file.createNewFile();

return file;

}

/**

* 在SD卡上创建目录

*

* @param dirName

*/

public File creatSDDir(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

*/

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

*/

public File write2SDFromInput(String path,String fileName,InputStream input){

File file = null;

OutputStream output = null;

try{

creatSDDir(path);

file = creatSDFile(path + fileName);

output = new FileOutputStream(file);

byte buffer [] = new byte[4 * 1024];

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

output.write(buffer);

}

output.flush();

}

catch(Exception e){

e.printStackTrace();

}

finally{

try{

output.close();

}

catch(Exception e){

e.printStackTrace();

}

}

return file;

}

}

=>>AndroidMainfest.xml

package="mars.download"

android:versionCode="1"

android:versionName="1.0">

android:label="@string/app_name">

=>>main.xml

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

>

android:id="@+id/downloadTxt"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="下载文本文件"

/>

android:id="@+id/downloadMp3"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="下载MP3文件 "

/>