package?com.imooc.io; import?java.io.File; import?java.io.IOException; import?java.io.RandomAccessFile; import?java.util.Arrays; public?class?RafDemo?{ ????public?static?void?main(String[]?args)?throws?IOException{ ????????File?demo?=new?File("demo"); ????????if(!demo.exists()) ????????????demo.mkdir(); ????????File?file?=new?File(demo,"raf.dat"); ????????if(!file.exists()) ????????????file.createNewFile(); ???????? ????????RandomAccessFile?raf=new?RandomAccessFile(file,?"rw"); ????????//指針的位置 ????????System.out.println(raf.getFilePointer()); ???????? ????????raf.write('A'); ????????System.out.println(raf.getFilePointer()); ????????raf.write('B'); ???????? ????????int?i=0x7fffffff; ????????//用write方法每次只能寫一個字節(jié)，如果要把i寫進去就得寫4次 ????????raf.write(i>>>24);//高八位 ????????raf.write(i>>>16); ????????raf.write(i>>>8); ????????raf.write(i); ????????System.out.println(raf.getFilePointer()); ???????? ????????//可以直接寫一個int ????????raf.writeInt(i); ???????? ????????String?s="中"; ????????byte[]?gbk=s.getBytes("gbk"); ????????raf.write(gbk); ????????System.out.println(raf.length()); ???????? ???????? ????????//讀文件，必須把指針移到頭部 ????????raf.seek(0); ????????//一次性讀取,把文件中的內(nèi)容都讀到字節(jié)數(shù)組 ????????byte[]?buf=new?byte[(int)raf.length()]; ????????raf.write(buf); ????????System.out.println(Arrays.toString(buf)); ???????? ???????? ???????? ????} }