java对文件进行CRC32校验

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import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.zip.CRC32;
import java.util.zip.CheckedInputStream;

public class ChecksumCRC32 {

public static long doChecksum(File file) {
long checksum=0;
try {
CheckedInputStream cis = null;
long fileSize = 0;
try {
// Computer CRC32 checksum
cis = new CheckedInputStream(new FileInputStream(file),
new CRC32());
fileSize = file.length();
} catch (FileNotFoundException e) {
System.err.println("File not found.");
System.exit(1);
}
byte[] buf = new byte[128];
while (cis.read(buf) >= 0) {
}
checksum = cis.getChecksum().getValue();
System.out.println(checksum + " " + fileSize + " " + file.getName());
} catch (IOException e) {
e.printStackTrace();
}

return checksum;
}
}