android平台上的文件下载,文件和文件的操作

android平台上对文件的操作和java基本上是相同的

注意用Environment.getExternalStorageDirectory()+"/"获得的SD目录最好

package duohuo.teng.net;

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 FileUtil {

	private String SDPATH;

	public FileUtil() {
		//获得SD卡的路劲
		SDPATH=Environment.getExternalStorageDirectory()+"/";	
	}
	
	
	/*创建文件
	 * 
	 * */
	public File createFile(String fileName) throws IOException{
	File file=new File(SDPATH+fileName);
	file.createNewFile();
		return file;
	}
	/*创建文件夹
	 * 
	 * */
	public File createDirs(String dirName){
		File file=new File(SDPATH+dirName);
		Boolean b=file.mkdirs();
		System.out.println(b);
		return file;
	}
	/*判断文件(夹)是否存在
	 * 
	 * */	
	public boolean isFileExist(String path){
		return new File(SDPATH+path).exists();
		
	}
	public File writeToSDFromInputStream(String path,String fileName,InputStream in){
		File file=null;
		OutputStream out = null;
		
		createDirs(path);
		try {
			 path=path+"/"+fileName;
			System.out.println(path);
		file=createFile(path);
		out=new FileOutputStream(file);
		byte[] buffer=new byte[4*1024];
		while(in.read(buffer)!=-1){
			out.write(buffer);

		}
		
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			try {
				if(out!=null)
				out.close();
				if(in!=null)
				in.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
			
		}
		
		
		return file;
	}
	/*delete file
	 * @return 0 文件不存在 1删除成功
	 * */
	public int deleteFile(String fileAllName){
		File file=new File(SDPATH+fileAllName);
	if(isFileExist(file.getPath())){
		return 0;
	}
	
	file.delete();
	return 1;

		
		
		
		
		
	}
	
}

下面是下载 

package duohuo.teng.net;

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;
import java.net.URLConnection;


public class HttpDownloadUtil {

	
	/*将文件保存为String
	 * @param urlStr 本机测试是不是ip不是localhost和127.0.0.1,这是指android的IP,电脑是10.0.2.2
	 * */
	public String downloadString(String urlStr){
		StringBuffer result=new StringBuffer();;
		URL url;
		InputStream in = null;
		BufferedReader reader=null;
		try {
			 url=new URL(urlStr);
			 HttpURLConnection con=(HttpURLConnection)url.openConnection();
			 in=con.getInputStream();
			
		reader=new BufferedReader(new InputStreamReader(in));
		
		String line;
		while((line=reader.readLine())!=null){
			result.append(line);
		}	
			
		} catch (MalformedURLException e) {
			e.printStackTrace();
		}catch (IOException e) {
			e.printStackTrace();
		}finally{
			try {
				if(reader!=null)
					reader.close();
				if(in!=null)
					in.close();
				
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
		}
		return result.toString();
	}
	/*将文件写入SD卡
	 * @return -1 写入失败 0存在 1写入成功
	 * @param urlStr 本机测试是不是ip不是localhost和127.0.0.1,这是指android的IP,电脑是10.0.2.2
	 * */
	
	
	public int downloadFile(String urlStr,String toPath,String fileName){
		try {
			URL url=new URL(urlStr);
		URLConnection con=url.openConnection();
		InputStream in=con.getInputStream();
		FileUtil fileUtil=new FileUtil();
		if(fileUtil.isFileExist(toPath+fileName)){
			
			return 0;
		}
		
		File file=fileUtil.writeToSDFromInputStream(toPath, fileName, in);
			
		if(file==null){
			return -1;
		}
		
		} catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return -1;
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return -1;
		}
		
		return 1;
		
		
		
		
	}
	
	
	
	
}