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需要给 AndroidManifest.xml里加上权限：
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>源码：
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
public class Copy_File extends Activity
{
private Button m_btn = null;
private final static String FROMPATH = "/mnt/sdcard/A/";
private final static String TOPATH = "/mnt/sdcard/B/";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
m_btn = (Button)findViewById(R.id.button1);
m_btn.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
if(copy(FROMPATH, TOPATH)==0)
{
Toast.makeText(Copy_File.this,"文件拷贝成功！！！",20000).show();
}else
{
Toast.makeText(Copy_File.this,"文件拷贝失败！！！",20000).show();
}
}
});
}
public int copy(String fromFile, String toFile)
{
//要复制的文件目录
File[] currentFiles;
File root = new File(fromFile);
//如同判断SD卡是否存在或者文件是否存在
//如果不存在则 return出去
if(!root.exists())
{
return -1;
}
//如果存在则获取当前目录下的全部文件 填充数组
currentFiles = root.listFiles();
//目标目录
File targetDir = new File(toFile);
//创建目录
if(!targetDir.exists())
{
targetDir.mkdirs();
}
//遍历要复制该目录下的全部文件
for(int i= 0;i<currentFiles.length;i++)
{
if(currentFiles[i].isDirectory())//如果当前项为子目录 进行递归
{
copy(currentFiles[i].getPath() + "/", toFile + currentFiles[i].getName() + "/");
}else//如果当前项为文件则进行文件拷贝
{
CopySdcardFile(currentFiles[i].getPath(), toFile + currentFiles[i].getName());
}
}
return 0;
}
//文件拷贝
//要复制的目录下的所有非子目录(文件夹)文件拷贝
public int CopySdcardFile(String fromFile, String toFile)
{
try
{
InputStream fosfrom = new FileInputStream(fromFile);
OutputStream fosto = new FileOutputStream(toFile);
byte bt[] = new byte[1024];
int c;
while ((c = fosfrom.read(bt)) > 0)
{
fosto.write(bt, 0, c);
}
fosfrom.close();
fosto.close();
return 0;
} catch (Exception ex)
{
return -1;
}
}
}