Android演示如何下载文件

演示Android下如何下载文件。先奉上代码下载地址。

点击打开链接

分析如下：

Downloader.java

public int downloadFile(String link) {int resultcode = -1;String filename = null;InputStream input = getInputStream(link);if (input != null) {File file = new File(link);if (file.isDirectory()) {file.list();} else {filename = file.getName();}if (filename != null) {FileUtility fu = new FileUtility();resultcode = fu.writeStreamToFile(true, true, DIR_NAME, filename,input);}}return resultcode;}}

步骤：

1. 根据String类型URL得到InputStream；
2. 创建目录、文件；
3. 写入Stream。
   

其中文件操作类代码如下FileUtility.java：

package com.freesoft.utility;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import android.os.Environment;import android.util.Log;public class FileUtility {private static int BUF_SIZE = 1024 * 4;private static String TAG = "FileUtility";private File createDir(String dirname) throws IOException {File dir = new File(dirname);if (dir.exists() != true)if (dir.mkdir() != true)throw new IOException();return dir;}private File createFile(boolean deleteIfExsit, String dirname, String filename) throws IOException {File file = new File(dirname + "/" + filename);if (file.exists() != true) {if (file.createNewFile() != true)throw new IOException();} else {if (deleteIfExsit) {if (!file.delete())throw new IOException();} else {if (!file.createNewFile())throw new IOException();}}return file;}public int writeStreamToFile(boolean toSDCard, boolean deleteIfExsit,String dirname, String filename, InputStream input) {int resultcode = -1;int len = 0;if (toSDCard == true)dirname = Environment.getExternalStorageDirectory() + "/" + dirname;try {createDir(dirname);File file = createFile(deleteIfExsit, dirname, filename);OutputStream output = new FileOutputStream(file);byte buf[] = new byte[BUF_SIZE];while ((len = input.read(buf)) != -1) {output.write(buf, 0, len);}output.flush();resultcode = 0;} catch (IOException e) {Log.v(TAG, "文件操作错误。");e.printStackTrace();}return resultcode;}}