java - Android保存文件到内存卡

Question

在下面的程序中，我得到了如下所示的异常。基本上我正在尝试做的是将文件从远程系统复制到设备。但是当保存到模拟器和设备上的存储卡时，我我遇到了异常。下面的异常来自模拟器，我可以说存储卡没有连接到模拟器，所以是异常。但是代码是否适用于物理设备。

如何让代码在模拟器和设备上运行

异常(exception):

 09-13 15:47:16.789: I/System.out(400): java.io.FileNotFoundException: /mnt/sdcard/Download/new.txt (Not a directory)

代码:

package com.scp2;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;

import com.jcraft.jsch.*;


import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.widget.Toast;

public class Scp2Activity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

            JSch jsch = new JSch();
            Session session = null;
            try {
                session = jsch.getSession("guest", "17.30.5.2", 22);

                session.connect();
                Toast.makeText(this,  "in try2" , Toast.LENGTH_SHORT).show();

                channel.connect();
                ChannelSftp sftpChannel = (ChannelSftp) channel;
                File ofile = new File(Environment.getExternalStoragePublicDirectory (Environment.DIRECTORY_DOWNLOADS),"new.txt");
                Toast.makeText(this, ofile.toString() , Toast.LENGTH_SHORT).show();
                                   try {
                    FileOutputStream f = new FileOutputStream(ofile);
                  sftpChannel.get("/root/a.txt","/mnt/sdcard/download/dd.txt");
                  /*OR What shoud the abobe statement be **/
              //sftpChannel.get("/root/a.txt",ofile); or this statement is correct

                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                         System.out.println(e.toString());
                }


                sftpChannel.exit();
                session.disconnect();
            } catch (JSchException e) {
                e.printStackTrace(); 

            } catch (SftpException e) {
                e.printStackTrace();

            }


    }
 }

Answer 1

这样做是为了创建文件；比你的更好更安全的方法

File dir = new File(Environment.getExternalStorageDirectory(),"/Downloads/");
dir.mkdirs();
String strFileName = "dd.html";
File file = new File(dir,strFileName);