如何在android中制作文件的副本?
问题
在我的应用程序中,我想保存具有不同名称的某个文件的副本(我从用户那里获得)
我真的需要打开文件的内容并将其写入另一个文件吗?
这样做的最佳方法是什么?
#1 热门回答(280 赞)
要复制文件并将其保存到目标路径,你可以使用以下方法。
public static void copy(File src, File dst) throws IOException {
InputStream in = new FileInputStream(src);
try {
OutputStream out = new FileOutputStream(dst);
try {
// Transfer bytes from in to out
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
} finally {
out.close();
}
} finally {
in.close();
}
}
在API 19上,你可以使用Java自动资源管理:
public static void copy(File src, File dst) throws IOException {
try (InputStream in = new FileInputStream(src)) {
try (OutputStream out = new FileOutputStream(dst)) {
// Transfer bytes from in to out
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
}
}
}
#2 热门回答(114 赞)
或者,你可以使用87563559复制文件。复制大文件时,它比字节复制方法更快.You can't use it if your file is bigger than 2GB though.
public void copy(File src, File dst) throws IOException {
FileInputStream inStream = new FileInputStream(src);
FileOutputStream outStream = new FileOutputStream(dst);
FileChannel inChannel = inStream.getChannel();
FileChannel outChannel = outStream.getChannel();
inChannel.transferTo(0, inChannel.size(), outChannel);
inStream.close();
outStream.close();
}
#3 热门回答(14 赞)
这对我很好
public static void copyFileOrDirectory(String srcDir, String dstDir) {
try {
File src = new File(srcDir);
File dst = new File(dstDir, src.getName());
if (src.isDirectory()) {
String files[] = src.list();
int filesLength = files.length;
for (int i = 0; i < filesLength; i++) {
String src1 = (new File(src, files[i]).getPath());
String dst1 = dst.getPath();
copyFileOrDirectory(src1, dst1);
}
} else {
copyFile(src, dst);
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void copyFile(File sourceFile, File destFile) throws IOException {
if (!destFile.getParentFile().exists())
destFile.getParentFile().mkdirs();
if (!destFile.exists()) {
destFile.createNewFile();
}
FileChannel source = null;
FileChannel destination = null;
try {
source = new FileInputStream(sourceFile).getChannel();
destination = new FileOutputStream(destFile).getChannel();
destination.transferFrom(source, 0, source.size());
} finally {
if (source != null) {
source.close();
}
if (destination != null) {
destination.close();
}
}
}