Android开发之下载Tomcat服务器的文件到模拟器的SD卡

    Tomcat服务器可以到Apache的官网去下载http://tomcat.apache.org/，如何配置和使用百度下也有很多介绍，只要把Java的SDK配下java_home环境变量就行了，因为Tomcat也是用Java程序写的所以需要依赖Java的库。如果配置成功在IE上输入：http://localhost:8080/回车就会出现Tomcat的主页

对SD卡进行操作需要新建一个工具类可以写入字节也可以写入字符  FileUitls.java

package com.example.utils;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.os.Environment;

/**
 * 文件管理类    在以后的开发中也可以使用这个工具类，提高代码的利用性
 * 只要是对SD卡的操作
 * 1、获取SD卡路径   getSDPATH
 * 2、在SD卡上根据传入的目录名创建目录  createSDDir
 * 3、在创建上目录后可以在该目录上创建文件    createSDFile
 * 4、检测文件是否存在  isFileExist
 * 5、将一个InputStream写入到SD卡中   write2SDFromInput
 * 6、将一个字符流写入到SD卡 write2SDFromWrite
 * 注：如果要写入SD卡，只要调用write2SDFromInput函数即可
 * @author Administrator
 *
 */
public class FileUitls {
	private static String SDPATH;
	
	public FileUitls(){
		//得到当前设备外部存储设备的目录
		SDPATH = Environment.getExternalStorageDirectory() + File.separator;
	}
	/**
	 * 获取当前SD卡的根目录
	 * @return
	 */
	public String getSDPATH(){
		return SDPATH;
	}
	/**
	 * SD卡上创建目录
	 */
	public File createSDDir(String dirName){
		File dir = new File(SDPATH + dirName);
		System.out.println("createSDDir " + SDPATH + dirName);
		dir.mkdir();
		return dir;
	}
	/**
	 * SD卡上创建文件
	 */
	public File createSDFile(String fileName)throws IOException{
		File file = new File(SDPATH + fileName);
		System.out.println("createSDFile " + SDPATH + fileName);
		file.createNewFile();
		return file;
	}
	
	
	/**
	 * 判断SD卡上的文件是否存在
	 */
	public boolean isFileExist(String fileName){
		File file = new File(SDPATH + fileName);
		return file.exists();
	}
	/**
	 * 将一个InputStream字节流写入到SD卡中
	 */
	public File write2SDFromInput(String Path, String FileName, InputStream input){
		File file = null;
		OutputStream output = null;   //创建一个写入字节流对象
		try{
			createSDDir(Path);    //根据传入的路径创建目录
			file = createSDFile(Path + FileName); //根据传入的文件名创建
			output = new FileOutputStream(file);
			byte buffer[] = new byte[4 * 1024];   //每次读取4K
			int num = 0;      //需要根据读取的字节大小写入文件
			while((num = (input.read(buffer))) != -1){
				output.write(buffer, 0, num);
			}
			output.flush();  //清空缓存
		}catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
		finally{
			try{
				output.close();
			}
			catch (Exception e) {
				// TODO: handle exception
				e.printStackTrace();
			}
		}
		return file;
	}
	
	/**
	 * 把传入的字符流写入到SD卡中
	 * @param Path
	 * @param FileName
	 * @param input
	 * @return
	 */
	public File write2SDFromWrite(String Path, String FileName, BufferedReader input){
		File file = null;
		FileWriter output = null;   //创建一个写入字符流对象
		BufferedWriter bufw = null;
		try{
			createSDDir(Path);    //根据传入的路径创建目录
			file = createSDFile(Path + FileName); //根据传入的文件名创建
			output = new FileWriter(file);
			bufw = new BufferedWriter(output);
			String line = null;
			while((line = (input.readLine())) != null){
				System.out.println("line = " + line);
				bufw.write(line);
				bufw.newLine();
			}
			bufw.flush();  //清空缓存
		}catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
		finally{
			try{
				bufw.close();
			}
			catch (Exception e) {
				// TODO: handle exception
				e.printStackTrace();
			}
		}
		return file;
	}
}

还需要创建一个下载工具类  HttpDownloader.java

对于下载类，要注意的就是下载文件变成乱码问题，如果有中文最好指定gb3212编码或UTF-8

package com.example.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(), "gb2312")); // 防止中文出现乱码  gb2312
			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();
	}

	/**
	 * 可以下载字节流文件到SD卡中
	 * 
	 * @param urlstr  要下载文件的URI地址
	 * @param Path  在SD卡上文件夹的路径
	 * @param FileName  在SD卡上文件的名称
	 * @return 该函数返回整型：-1代表下载失败，0代表下载成功，1代表文件已经存在
	 */
	public int download(String urlstr, String Path, String FileName) {
		InputStream inputstream = null;
		BufferedReader buffer = null;
		try {
			FileUitls fileUitls = new FileUitls();
			System.out.println(Path + FileName);
			if (fileUitls.isFileExist(Path + FileName)) {
				return 1;
			} else {
				// 获取URI中的字节流
				inputstream = getInputStreamFromUrl(urlstr);
				// 把字节流转换成字符流
				buffer = new BufferedReader(new InputStreamReader(inputstream,
						"gb2312")); // 防止中文出现乱码   UTF-8
				File resultFile = fileUitls.write2SDFromWrite(Path, FileName,
						buffer);
				if (resultFile == null) {
					return -1;
				}
			}

		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
			return -1;
		} finally {
			try {
				if(buffer != null)
					buffer.close();
			} catch (Exception e) {
				// TODO: handle exception
				e.printStackTrace();
			}
		}
		return 0;
	}

	/**
	 * 可以下载字符流和字节流文件到SD卡中
	 * 
	 * @param urlstr
	 * @param Path
	 * @param FileName
	 * @return 该函数返回整型：-1代表下载失败，0代表下载成功，1代表文件已经存在
	 */
	public int downFile(String urlstr, String Path, String FileName) {
		InputStream inputstream = null;
		try {
			FileUitls fileUitls = new FileUitls();
			if (fileUitls.isFileExist(Path + FileName)) {
				return 1;
			} else {
				inputstream = getInputStreamFromUrl(urlstr);
				File resultFile = fileUitls.write2SDFromInput(Path, FileName,
						inputstream);
				if (resultFile == null) {
					return -1;
				}
			}

		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
			return -1;
		} finally {
			try {
				inputstream.close();
			} catch (Exception e) {
				// TODO: handle exception
				e.printStackTrace();
			}
		}
		return 0;
	}

	/**
	 * 根据URL得到输入流
	 * 
	 * @param urlstr
	 * @return
	 * @throws MalformedURLException
	 * @throws IOException
	 */
	private InputStream getInputStreamFromUrl(String urlstr)
			throws MalformedURLException, IOException {
		// TODO Auto-generated method stub
		url = new URL(urlstr);
		HttpURLConnection urlConn = (HttpURLConnection) url.openConnection();
		InputStream inputStream = urlConn.getInputStream();
		return inputStream;
	}
}

在主界面上有添加两个按钮，分别下载歌词和歌曲

package com.example.download;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

import com.example.utils.HttpDownloader;

public class Download extends Activity {

	private Button downloadtxt;
	private Button downloadmp3;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		downloadtxt = (Button) findViewById(R.id.download_txt);
		downloadtxt.setOnClickListener(new DownLoadTxt());
		downloadmp3 = (Button) findViewById(R.id.download_mp3);
		downloadmp3.setOnClickListener(new DownLoadMp3());
	}

	/**
	 * 下载文本文件，主要是字符流
	 * @author Administrator
	 *
	 */
	class DownLoadTxt implements OnClickListener {

		@Override
		public void onClick(View v) {

			// TODO Auto-generated method stub
			HttpDownloader httpDownloader = new HttpDownloader();
			int result = httpDownloader.download(
					"http://192.168.0.152:8080/mp3/a1.lrc", "mp3Test/abc/",
					"a1.lrc");
			System.out.println("down load txt result = " + result);
			// String lrc =
			// httpDownloader.download("http://192.168.0.152:8080/mp3/a1.lrc");
			// System.out.println("down load txt = " + lrc);
		}

	}

	/**
	 * 下载字节流文件，也可以下载字符流文件
	 * @author Administrator
	 *
	 */
	class DownLoadMp3 implements OnClickListener {

		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			HttpDownloader httpDownloader = new HttpDownloader();
			int result = httpDownloader.downFile(
					"http://192.168.0.152:8080/mp3/a1.mp3", "mp3Test/",
					"a1.mp3");
			System.out.println("downfile load txt result = " + result);
		}
	}
}

其中192.168.0.152是本地IP地址8080是Tomcat的端口号

下载后的两个文件如图

样例代码

点击打开链接