Java文件读取前中后200字节
Java文件读取前40+10字节，分两次读，一次读20字节
public static void main(String[] args) throws Exception {
//String hex = "0x0000000003F985B8";
/*String hex = "0x0000000003F9A790";
Long x = Long.parseLong(hex.substring(2),16);//从第2个字符开始截取
System.out.println(x);*/
//读取文件时缓冲区大小
//int BUFFER_SIZE = 1 * 1024 * 1024;
int BUFFER_SIZE = 20;
FileInputStream fis = new FileInputStream("E://扫描//2018-3-12//xwsun//addr.txt");
InputStream in = new BufferedInputStream(fis,BUFFER_SIZE);
byte[] buffer = new byte[BUFFER_SIZE];
byte[] lastByte = new byte[10];
long count = 0;
//int byteNum = 20;
//in.skip(byteNum); //跳过前byteNum的字节不扫描
int postion = in.read(buffer);
int perReadByte = postion;
while (perReadByte != -1)
{
byte[] tempBuffer = null;
if(count >0)
{
tempBuffer = new byte[buffer.length + lastByte.length];
for(int i =0;i<lastByte.length;i++)
{
tempBuffer[i] = lastByte[i];
}
for(int i =0;i<buffer.length;i++)
{
tempBuffer[i + lastByte.length] = buffer[i];
}
}else{
tempBuffer = buffer;
}
//输出一次读出的内容（一次读出20字节）
System.out.println(new String(tempBuffer,"UTF-8")+"==========================");
int available = in.available();
//最后300个字节
lastByte = new byte[available > 10 ? 10 : available];
for(int i=buffer.length - lastByte.length,j=0;i<buffer.length;i++,j++)
{
lastByte[j] = buffer[i];
}
buffer = new byte[BUFFER_SIZE];
count ++ ;
if(count == 2)
{
break;
}
perReadByte = in.read(buffer);
}
}
Java文件读取前40+10字节，分两次读，一次读20字节
