利用 org.apache.commons.io.FileUtils快速读写文件

利用 org.apache.commons.io.FileUtils快速读写文件

http://php.11519.net/5jblog/?p=475

  String fileName = "C://11.txt";
  File file = new File(fileName);
  String fileContent = "";
  try {
   fileContent = org.apache.commons.io.FileUtils.readFileToString(file, "GBK");
  } catch (IOException e) {
   e.printStackTrace();
  }
  fileContent +="Helloworld";
  try {
   org.apache.commons.io.FileUtils.writeStringToFile(file, fileContent, "GBK");
  } catch (IOException e) {
   e.printStackTrace();
  }

 

其他参考

Commons IO方便读写文件的工具类:http://laoyu.info/archives/282.html

Commons IO是apache的一个开源的工具包,封装了IO操作的相关类,使用Commons IO可以很方便的读写文件,url源代码等.

普通地读取一个网页的源代码的代码可能如下

1. InputStream  in =   new   URL (   "http://laoyu.info"   ). openStream ( ) ;
2.   try   {
3.     InputStreamReader  inR =   new   InputStreamReader (  in   ) ;
4.     BufferedReader  buf =   new   BufferedReader (  inR   ) ;
5.     String  line ;
6.     while   (   (  line = buf. readLine ( )   )   !=   null   )   {
7.       System. out. println (  line   ) ;
8.     }
9.   }   finally   {
10.    in. close ( ) ;
11.   }

使用了Commons IO,则可以大大简化代码.如下:

1. InputStream  in =   new   URL (   "http://laoyu.info"   ). openStream ( ) ;
2.   try   {
3.     System. out. println (  IOUtils. toString (  in   )   ) ;
4.   }   finally   {
5.    IOUtils. closeQuietly (in ) ;
6.   }

Commons IO里的常用类

FileUtils包含了文件操作的相关方法.
下面的代码用于读取磁盘上的某个文件:

1. File  file =   new   File ( "c:/test.txt" ) ;
2. List  lines = FileUtils. readLines (file,   "UTF-8" ) ;

FileSystemUtils 可以获得指定磁盘路径的可用空间

1. long  freeSpace = FileSystemUtils. freeSpace ( "d:/" ) ;

文件复制代码:

1. File  src =   new   File ( "src.txt" ) ;
2. File  dest =   new   File ( "dest.txt" ) ;
3. FileUtils. copyFile (src, dest ) ;

补充:
方便地下载文件到本地

1. InputStream  in =   new
2. URL ( "http://www.baidu.com/img/baidu_logo.gif" ). openStream ( ) ;
3.     byte   [ ]  gif = IOUtils. toByteArray (in ) ;
4.     //IOUtils.write(gif,new FileOutputStream(new File("c:/test.gif")));
5.   FileUtils. writeByteArrayToFile ( new   File ( "c:/test.gif" ),gif ) ;
6.   IOUtils. closeQuietly (in ) ;

 

 

分享 commons io 工具类 代码:http://www.javaeye.com/topic/575996

输入流复制到输出流 

 public class IoTest {

     /**
      * @param args
      */
     public static void main(String[] args) throws Exception {
         // TODO Auto-generated method stub
         Writer write = new FileWriter("c:\\kk.dat");

         InputStream ins = new FileInputStream(new File("c:\\text.txt"));

         IOUtils.copy(ins, write);
         write.close();

         ins.close();
     }

 }

文本写入指定文件 

 public class FileWirterTest {

     /**
      * @param args
      */
     public static void main(String[] args) throws Exception{
         // TODO Auto-generated method stub

         String name = "my name is panxiuyan";

         File file =  new File("c:\\name.txt");

         FileUtils.writeStringToFile(file, name);

     }

 }

将输入流转换成文本 

 public class URLIoTest {

     /**
      * @param args
      */
     public static void main(String[] args) throws Exception {
         // TODO Auto-generated method stub
         URL url = new URL("http://www.dimurmill.com");

         InputStream ins = url.openStream();

         String contents = IOUtils.toString(ins,"UTF-8");
         System.out.println( "Slashdot: " + contents );


     }

 }

关闭相关流

 public class IoCloseTest {

     /**
      * @param args
      */
     public static void main(String[] args) {
         // TODO Auto-generated method stub

         File file = null;

         InputStream ins = null;
         try{
             file = new File("C:\\Test.java");

             ins = new FileInputStream(file);
         }catch(Exception e){
             e.printStackTrace();
         }finally{
             IOUtils.closeQuietly(ins);
         }

     }

 }

文件复制

 public class FileCopyTest {

     /**
      * @param args
      */
     public static void main(String[] args) throws Exception{
         // TODO Auto-generated method stub

         File srcfile = new File("c:\\Test.java");

         File destfile = new File("c:\\Test.java.bak");


         FileUtils.copyFile(srcfile, destfile);

     }

 }

文件复制指定的目录 

 public class FileCopyTest {

     /**
      * @param args
      */
     public static void main(String[] args) throws Exception{
         // TODO Auto-generated method stub

         File srcfile = new File("c:\\Test.java");

         File destDir = new File("D:\\");


         FileUtils.copyFileToDirectory(srcfile, destDir);

     }

 }

网络流保存为文件 

 public class URLToFileTest {

     /**
      * @param args
      */
     public static void main(String[] args) throws Exception{
         // TODO Auto-generated method stub

         URL url = new URL("http://www.163.com");

         File file = new File("c:\\163.html");

         FileUtils.copyURLToFile(url, file);

     }

 }

文件目录操作 

 public class DirOper {

     /**
      * @param args
      */
     public static void main(String[] args) throws Exception {
         // TODO Auto-generated method stub

         File dir = new File("c:\\test");

         FileUtils.cleanDirectory(dir);//清空目录下的文件

         FileUtils.deleteDirectory(dir);//删除目录和目录下的文件

     }

 }

目录大小 

 long size = FileUtils.sizeOfDirectory(dir);

目录操作 

 File testFile = new File( "testFile.txt" );

      //如果不存在,新建

     // 如果存在,修改文件修改时间

     FileUtils.touch( testFile );

记录流的读取写入字节数 

 File test = new File( "test.dat" );

 //输出流的统计
 CountingOutputStream countStream = null;

 //输入流的统计
 //CountingInputStream countStream = null;




 try {

     FileOutputStream fos = new FileOutputStream( test );

     countStream = new CountingOutputStream( fos );

     countStream.write( "Hello".getBytes( ) );

 } catch( IOException ioe ) {

     System.out.println( "Error writing bytes to file." );

 } finally {

     IOUtils.closeQuietly( countStream );

 }



 if( countStream != null ) {

     int bytesWritten = countStream.getCount( );

     System.out.println( "Wrote " + bytesWritten + " bytes to test.dat" );

 }

相同的内容写入不同的文本 

 File test1 = new File("split1.txt");

 File test2 = new File("split2.txt");

 OutputStream outStream = null;



 try {

     FileOutputStream fos1 = new FileOutputStream( test1 );

     FileOutputStream fos2 = new FileOutputStream( test2 );

     //包含不同的文本
     outStream = new TeeOutputStream( fos1, fos2 );



     outStream.write( "One Two Three, Test".getBytes( ) );

     outStream.flush( );

 } catch( IOException ioe ) {

     System.out.println( "Error writing to split output stream" );

 } finally {

     IOUtils.closeQuietly( outStream );

 }