public int peek() throws IOException{
        peekindex = 0;
        int v = peek(peekindex ++);
        if(v == -1){
            end = true;
        }
        return v;
    }
public int peek() throws IOException{
        peekindex = 0;
        int v = peek(peekindex ++);
        if(v == -1){
            end = true;
        }
        return v;
    }
public int peek ( ) throws IOException { peekindex = 0 ; int v = peek ( peekindex ++ ) ; if ( v == - 1 ) { end = true ; } return v ; }
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@return 头部字节
@throws IOException
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