1. 数据来源
InputStream 本质上是byte[] ,input 意味者将数据从外部获取到内存,并封装到byte[]中。
子类:
FileInputStream流是从文件中获取数据(文件,不在内存中的数据);
ByteArrayInputStream从内存中获取数据(已经存在于内存的数据);
最终,都会产生一个InputStream类型的对象。
2. 代码解析
2.1 简单复制文件
public static void main(String[] args) throws IOException {
InputStream inputStream = new FileInputStream("D:\\DAY_WORK\\2020\\month_10\\10_月.txt");
OutputStream outputStream = new FileOutputStream("D:\\DAY_WORK\\2020\\month_10\\10_copy.txt");
byte[] bytes = new byte[inputStream.available()];
inputStream.read(bytes);
outputStream.write(bytes);
inputStream.close();
outputStream.close();
}
2.2 1024为单位复制文件
public static void main(String[] args) throws IOException {
InputStream inputStream = new FileInputStream("D:\\DAY_WORK\\2020\\month_10\\My Favorite 修改说明.docx");
OutputStream outputStream = new FileOutputStream("D:\\DAY_WORK\\2020\\month_10\\My Favorite 修改说明copy.docx");
byte[] bytes = new byte[1024];
int n;
final int end = -1;
while (end != (n = inputStream.read(bytes))) {
outputStream.write(bytes, 0, n);
}
inputStream.close();
outputStream.close();
}
2.3 文件内容追加一句话
public static void main(String[] args) throws IOException {
OutputStream outputStream = new FileOutputStream("D:\\DAY_WORK\\2020\\month_10\\10_copy.txt", true);
String content = "\n今天又是 nice 的一天";
byte[] bytes = content.getBytes();
outputStream.write(bytes);
outputStream.close();
}
3. outputstream 和 Writer/FileWriter 的区别
outPutStream 以byte为单位;
Writer/FileWriter 以字符为单位,存在编码问题。