当生活像一首歌那样轻快流畅时，笑颜常开乃易事；而在一切事都不妙时仍能微笑的人，是真正的乐观。——威尔科克斯
曾经我们使用java的IO流复制文件时是这么写的
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| package com.ruben;
import java.io.*;
import java.util.Optional;
public class FileDemo {
private static final String FILE_PATH = "D:/file/files/ps/2077.png";
private static final String TARGET_PATH = "D:/file/files/ps/1977.png";
public static void main(String[] args) {
InputStream dataInputStream = null;
OutputStream output = null;
try {
dataInputStream = new FileInputStream(FILE_PATH);
output = new FileOutputStream(TARGET_PATH);
byte[] buffer = new byte[1024];
int length;
while ((length = dataInputStream.read(buffer)) > 0) {
output.write(buffer, 0, length);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
Optional.ofNullable(output).ifPresent(outputStream -> {
try {
outputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
});
Optional.ofNullable(dataInputStream).ifPresent(inputStream -> {
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
});
}
}
}
|
可以看到在finally里我们关闭流的时候要写一大堆，非常麻烦
现在推荐使用这种写法
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| package com.ruben;
import java.io.*;
import java.util.Optional;
public class FileDemo {
private static final String FILE_PATH = "D:/file/files/ps/2077.png";
private static final String TARGET_PATH = "D:/file/files/ps/1977.png";
public static void main(String[] args) {
try (
InputStream dataInputStream = new FileInputStream(FILE_PATH);
OutputStream output = new FileOutputStream(TARGET_PATH)
) {
byte[] buffer = new byte[1024];
int length;
while ((length = dataInputStream.read(buffer)) > 0) {
output.write(buffer, 0, length);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
|
使用try()catch{}写法，可以自动关闭流