网络下载文件及存到sd卡--Android学习笔记

网络上下载东西的时候要记得在AndroidManifest.xml中申明<uses-permission  android:name="android.permission.INTERNET" />

1.string类型的内容下载

2.下载其他任意类型的文件如MP3。

package com.download;

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.URL;

import com.utils.FileUtils;

public class HttpDownloader {
    public String download(String urlStr) {
        StringBuffer sb = new StringBuffer();
        String line = null;
        BufferedReader buffer = null;
        try {
            /*
             * 创建URL,调用openConnection()方法打开连接，用getInputStream()
             * 获取字节流，转化成InputStreamReader的字符流，在套一个BufferedReader
             * 可以调用BufferedReader的readLine()方法，使用起来更方便
             */
            URL 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) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            try {
                buffer.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return sb.toString();
    }

    public int downFile(String urlStr, String path, String fileName) {
        InputStream inputstream = null;
        try {
            FileUtils fileUtils = new FileUtils();
            if (fileUtils.isFileExist(fileName, path))
                return 1;
            else {
                URL url = new URL(urlStr);
                HttpURLConnection urlconn = (HttpURLConnection) url
                        .openConnection();
                inputstream = urlconn.getInputStream();
                File result = fileUtils.write2SDFromInput(path, fileName,
                        inputstream);
                if (result == null)
                    return -1;
            }

        } catch (Exception e) {
            // TODO: handle exception
        } finally {
            try {
                inputstream.close();
            } catch (Exception e2) {
                // TODO: handle exception
            }
        }
        return 0;
    }
}

 

3.sd的操作

package mars.utils;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

import mars.model.Mp3Info;
import android.os.Environment;

public class FileUtils {
    private String SDCardRoot;

    public FileUtils() {
        // 得到当前外部存储设备的目录
        SDCardRoot = Environment.getExternalStorageDirectory()
                .getAbsolutePath()
                + File.separator;
        //SDCardRoot = Environment.getExternalStorageDirectory() + "/";
    }

    /**
     * 在SD卡上创建文件
     * 
     * @throws IOException
     */
    public File createFileInSDCard(String fileName, String dir)
            throws IOException {
        File file = new File(SDCardRoot + dir + File.separator + fileName);
        //File file = new File(SDCardRoot + fileName);
        System.out.println("file---->" + file);
        file.createNewFile();
        return file;
    }

    /**
     * 在SD卡上创建目录
     * 
     * @param dirName
     */
    public File creatSDDir(String dir) {
        File dirFile = new File(SDCardRoot + dir + File.separator);
        //File dirFile = new File(SDCardRoot + dir );
        System.out.println(dirFile.mkdirs());
        return dirFile;
    }

    /**
     * 判断SD卡上的文件夹是否存在
     */
    public boolean isFileExist(String fileName, String path) {
        File file = new File(SDCardRoot + path + File.separator + fileName);
        //File file = new File(SDCardRoot + 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 = createFileInSDCard(fileName, path);
            output = new FileOutputStream(file);
            byte buffer[] = new byte[4 * 1024];
            int temp;
            //int read( )读取一个字节，返回值为所读的字节 
            while ((temp = input.read(buffer)) != -1) {
            //void write( byte b[ ], int off, int len ),
            //把字节数组b中从下标off开始，长度为len的字节写入流中
                output.write(buffer, 0, temp);
            }
            output.flush();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                output.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return file;
    }

    /**
     * 读取目录中的Mp3文件的名字和大小
     */
    public List<Mp3Info> getMp3Files(String path) {
        List<Mp3Info> mp3Infos = new ArrayList<Mp3Info>();
        File file = new File(SDCardRoot + File.separator + path);
        File[] files = file.listFiles();
        FileUtils fileUtils = new FileUtils();
        for (int i = 0; i < files.length; i++) {
            if (files[i].getName().endsWith("mp3")) {
                Mp3Info mp3Info = new Mp3Info();
                mp3Info.setMp3Name(files[i].getName());
                mp3Info.setMp3Size(files[i].length() + "");
                String temp [] = mp3Info.getMp3Name().split("\\.");
                String eLrcName = temp[0] + ".lrc";
                if(fileUtils.isFileExist(eLrcName, "/mp3")){
                    mp3Info.setLrcName(eLrcName);
                }
                mp3Infos.add(mp3Info);
            }
        }
        return mp3Infos;
    }

}

 

2012-10-12