java文件读写
一.获得控制台用户输入的信息
public String getInputMessage() throws IOException { System.out.println("请输入您的命令∶"); byte buffer[]=new byte[1024]; int count=System.in.read(buffer); char[] ch=new char[count-2];//最后两位为结束符,删去不要 for(int i=0;i<count-2;i++) ch[i]=(char)buffer[i]; String str=new String(ch); return str; }
二.复制文件
public void copyFile(String src,String dest) throws IOException { FileInputStream in=new FileInputStream(src); File file=new File(dest); if(!file.exists()) file.createNewFile(); FileOutputStream out=new FileOutputStream(file); int c; byte buffer[]=new byte[1024]; while((c=in.read(buffer))!=-1)...{ for(int i=0;i<c;i++) out.write(buffer[i]); } in.close(); out.close(); }
三.文件重命名
public void renameFile(String path,String oldname,String newname) { if(!oldname.equals(newname)) {//新的文件名和以前文件名不同时,才有必要进行重命名 File oldfile=new File(path+"/"+oldname); File newfile=new File(path+"/"+newname); if(newfile.exists())//若在该目录下已经有一个文件和新文件名相同,则不允许重命名 System.out.println(newname+"已经存在!"); else { oldfile.renameTo(newfile); } } }
四.转移文件目录
public void changeDirectory(String filename,String oldpath,String newpath,boolean cover) { if(!oldpath.equals(newpath)) { File oldfile=new File(oldpath+"/"+filename); File newfile=new File(newpath+"/"+filename); if(newfile.exists()) {//若在待转移目录下,已经存在待转移文件 if(cover)//覆盖 oldfile.renameTo(newfile); else System.out.println("在新目录下已经存在:"+filename); } else { oldfile.renameTo(newfile); } } }
五.创建文件(文件夹)
//创建文件夹 public void createDir(String path) { File dir=new File(path); if(!dir.exists()) dir.mkdir(); }
//创建新文件 public void createFile(String path,String filename) throws IOException { File file=new File(path+"/"+filename); if(!file.exists()) file.createNewFile(); }
六.删除文件(文件夹)
//删除文件 public void delFile(String path,String filename)...{ File file=new File(path+"/"+filename); if(file.exists()&&file.isFile()) file.delete(); }
//删除目录 public void delDir(String path) { File dir=new File(path); if(dir.exists()) { File[] tmp=dir.listFiles(); for(int i=0;i<tmp.length;i++) { if(tmp[i].isDirectory()) { //递归 delDir(path+"/"+tmp[i].getName()); } else { tmp[i].delete(); } } dir.delete(); } }
七.读文件
//利用FileInputStream读取文件 public String FileInputStreamDemo(String path) throws IOException { File file=new File(path); if(!file.exists()||file.isDirectory()) throw new FileNotFoundException(); FileInputStream fis=new FileInputStream(file); byte[] buf = new byte[1024]; StringBuffer sb=new StringBuffer(); while((fis.read(buf))!=-1) { sb.append(new String(buf)); buf=new byte[1024]; //重新生成,避免和上次读取的数据重复 } return sb.toString(); }
//利用BufferedReader读取 public String BufferedReaderDemo(String path) throws IOException { File file=new File(path); if(!file.exists()||file.isDirectory()) throw new FileNotFoundException(); BufferedReader br=new BufferedReader(new FileReader(file)); String temp=null; StringBuffer sb=new StringBuffer(); temp=br.readLine(); while(temp!=null) { sb.append(temp+" "); temp=br.readLine(); } return sb.toString(); }
//利用dom4j读取xml文件 public Document readXml(String path) throws DocumentException, IOException { File file=new File(path); BufferedReader bufferedreader = new BufferedReader(new FileReader(file)); SAXReader saxreader = new SAXReader(); Document document = (Document)saxreader.read(bufferedreader); bufferedreader.close(); return document; }
八.写文件
//利用PrintStream写文件 public void PrintStreamDemo()...{ try ...{ FileOutputStream out=new FileOutputStream("D:/test.txt"); PrintStream p=new PrintStream(out); for(int i=0;i<10;i++) p.println("This is "+i+" line"); } catch (FileNotFoundException e) { e.printStackTrace(); } }
//利用StringBuffer写文件 public void StringBufferDemo() throws IOException { File file=new File("/root/sms.log"); if(!file.exists()) file.createNewFile(); FileOutputStream out=new FileOutputStream(file,true); for(int i=0;i<10000;i++) { StringBuffer sb=new StringBuffer(); sb.append("这是第"+i+"行:前面介绍的各种方法都不关用,为什么总是奇怪的问题 "); out.write(sb.toString().getBytes("utf-8")); //write的参数可以是字节,也可以是字节数组 } out.close(); }