Hi Team,我试图在二进制文件中找到一个String“Henry”,并将String更改为另一个字符串。 FYI文件是对象序列化的输出。 Original Question here
我是新手搜索字节,想象这个代码会搜索我的byte []并交换它。但它并没有接近工作它甚至找不到匹配。
{
byte[] bytesHenry = new String("Henry").getBytes();
byte[] bytesSwap = new String("Zsswd").getBytes();
byte[] seekHenry = new byte[bytesHenry.length];
RandomAccessFile file = new RandomAccessFile(fileString,"rw");
long filePointer;
while (seekHenry != null) {
filePointer = file.getFilePointer();
file.readFully(seekHenry);
if (bytesHenry == seekHenry) {
file.seek(filePointer);
file.write(bytesSwap);
break;
}
}
}
好的,我看到了bytesHenry==seekHenry
问题并将换成Arrays.equals( bytesHenry , seekHenry )
我想每次读取5个字节时,我需要移动-4个字节的位置。
宾果它现在找到它
while (seekHenry != null) {
filePointer = file.getFilePointer();
file.readFully(seekHenry);;
if (Arrays.equals(bytesHenry,
seekHenry)) {
file.seek(filePointer);
file.write(bytesSwap);
break;
}
file.seek(filePointer);
file.read();
}
答案 0 :(得分:1)
以下内容适用于您,请参阅返回第一个匹配项匹配的索引的方法search(byte[] input, byte[] searchedFor)
,或-1。
public class SearchBuffer {
public static void main(String[] args) throws UnsupportedEncodingException {
String charset= "US-ASCII";
byte[] searchedFor = "ciao".getBytes(charset);
byte[] input = "aaaciaaaciaojjcia".getBytes(charset);
int idx = search(input, searchedFor);
System.out.println("index: "+idx); //should be 8
}
public static int search(byte[] input, byte[] searchedFor) {
//convert byte[] to Byte[]
Byte[] searchedForB = new Byte[searchedFor.length];
for(int x = 0; x<searchedFor.length; x++){
searchedForB[x] = searchedFor[x];
}
int idx = -1;
//search:
Deque<Byte> q = new ArrayDeque<Byte>(input.length);
for(int i=0; i<input.length; i++){
if(q.size() == searchedForB.length){
//here I can check
Byte[] cur = q.toArray(new Byte[]{});
if(Arrays.equals(cur, searchedForB)){
//found!
idx = i - searchedForB.length;
break;
} else {
//not found
q.pop();
q.addLast(input[i]);
}
} else {
q.addLast(input[i]);
}
}
return idx;
}
}
答案 1 :(得分:0)
来自Fastest way to find a string in a text file with java:
我在MIMEParser中发现的最佳实现:https://github.com/samskivert/ikvm-openjdk/blob/master/build/linux-amd64/impsrc/com/sun/xml/internal/org/jvnet/mimepull/MIMEParser.java
/**
* Finds the boundary in the given buffer using Boyer-Moore algo.
* Copied from java.util.regex.Pattern.java
*
* @param mybuf boundary to be searched in this mybuf
* @param off start index in mybuf
* @param len number of bytes in mybuf
*
* @return -1 if there is no match or index where the match starts
*/
private int match(byte[] mybuf, int off, int len) {
还需要:
private void compileBoundaryPattern();