Android 下载文件及写入SD卡_移动开发_编程开发_程序员俱乐部

Android 下载文件及写入SD卡,实例代码

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<?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>

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<?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> 

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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;
	}
}

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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];
			while((input.read(buffer)) != -1){
				output.write(buffer);
			}
			output.flush();
		} 
		catch (Exception e) {
			e.printStackTrace();
		}
		finally{
			try {
				output.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return file;
	}

}

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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"/>