所以我有二进制 FRX 文件,我需要从中提取字符串到 Java 中。
我将其写入我的 Java 程序中,如下所示:
FileInputStream ReadFRX = null ;
FileOutputStream TempCapt = null ;
try{
// refNum is hex number on end of VB form property converted to decimal, ex: $"frmResidency.frx":0134
int refNum = Integer.parseInt(line.substring(line.length() - 4, line.length()), 16);
// FRXtemp.txt is created, to temporarily write FRX captions onto to be read from.
PrintWriter writer = new PrintWriter("FRXtemp.txt", "UTF-8");
writer.close();
//opens corresponding FRX file to read into
ReadFRX = new FileInputStream("FRXFiles\\"+curFrmName + ".frx");
//aLittleEndian... must be used to match readInt() little-endianness
LittleEndianDataInputStream ActReadFRX = new LittleEndianDataInputStream(ReadFRX);
TempCapt = new FileOutputStream("FRXtemp.txt");
ActReadFRX.skipBytes(refNum);
int length = ActReadFRX.readInt();
int c;
for (c = 0; c < length; c++) {
// first read byte and check for EOF
TempCapt.write(ActReadFRX.read());
}
}
//If caption is not read properly (ie. possibly wrong bytes), EOF Exception will occur and designer will break
catch (EOFException e){
System.out.println("ERROR : FRX Caption property was mishandled");
break;
}
//Read data from FRXtemp.txt into string
String actCaption = "\"" + new Scanner(new File("FRXtemp.txt")).useDelimiter("\\A").next() + " \" ";
这工作得很好,但是我认为写入临时文件以便我可以读取它是非常没有必要的。
为什么我想不出更有效的方法:
我觉得更实用的方法是使用 Byte[] Array
,然后将其转换为字符串,但是我必须只有其中的字节字符串被存储。研究使我相信,RandomAccessFile 是必要的,这样我就可以设置从 ReadInt 开始读取字节的偏移量,但是 RandomAccessFile 假设 big-字节序格式,而我有小字节序格式。我显然可以转换,但是此时我当前的解决方案似乎同样可行。
我的问题是,是否有一种有效的方法来转换与 4 字节整数对应的特定字节部分(来自小端格式的二进制文件) ) 转换为 Java 中的字符串?
我觉得我一定忽略了一些更简单的事情。谢谢:)
最佳答案
您可以通过多种方式执行此操作,但最简单的可能是。
try (DataInputStream dis = new DataInputStream(new FileInputStream(file))) {
dis.skip(bytesToSkip);
int length = Integer.reverseBytes(dis.readInt());
byte[] bytes = new bytes[length];
dis.readFully(bytes);
return new String(bytes, "UTF-8");
}
您可能一直在寻找的方法在Integer
中
/**
* Returns the value obtained by reversing the order of the bytes in the
* two's complement representation of the specified {@code int} value.
*
* @param i the value whose bytes are to be reversed
* @return the value obtained by reversing the bytes in the specified
* {@code int} value.
* @since 1.5
*/
public static int reverseBytes(int i) {
return ((i >>> 24) ) |
((i >> 8) & 0xFF00) |
((i << 8) & 0xFF0000) |
((i << 24));
}
关于java - 如何最有效地将二进制文件中的特定字节转换为字符串,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/28329098/