java文件读写

.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();
         }
     }

  

.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;
     }

  

.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();
}

  

posted @ 2014-04-17 19:55  hwu_harry  阅读(178)  评论(0编辑  收藏  举报