org.apache.commons.io.FileUtils学习

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

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

API:http://commons.apache.org/io/api-release/org/apache/commons/io/FileUtils.html

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. InputStreamin = new URL ( "http://laoyu.info" ). openStream ( ) ;
2. try {
3. InputStreamReaderinR = new InputStreamReader (in ) ;
4. BufferedReaderbuf = new BufferedReader (inR ) ;
5. Stringline ;
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. InputStreamin = 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. Filefile = new File ( "c:/test.txt" ) ;
2. Listlines = FileUtils. readLines (file, "UTF-8" ) ;

FileSystemUtils 可以获得指定磁盘路径的可用空间

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

文件复制代码:

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

补充:
方便地下载文件到本地

1. InputStreamin = 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

 publicclassIoTest{

 /**
 *@paramargs
 */
 publicstaticvoidmain(String[]args)throwsException{
 //TODOAuto-generatedmethodstub
 Writerwrite=newFileWriter("c:\\kk.dat");

 InputStreamins=newFileInputStream(newFile("c:\\text.txt"));

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

 ins.close();
 }

 }

文本写入指定文件

 publicclassFileWirterTest{

 /**
 *@paramargs
 */
 publicstaticvoidmain(String[]args)throwsException{
 //TODOAuto-generatedmethodstub

 Stringname="mynameispanxiuyan";

 Filefile=newFile("c:\\name.txt");

 FileUtils.writeStringToFile(file,name);

 }

 }

将输入流转换成文本

 publicclassURLIoTest{

 /**
 *@paramargs
 */
 publicstaticvoidmain(String[]args)throwsException{
 //TODOAuto-generatedmethodstub
 URLurl=newURL("http://www.dimurmill.com");

 InputStreamins=url.openStream();

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


 }

 }

关闭相关流

 publicclassIoCloseTest{

 /**
 *@paramargs
 */
 publicstaticvoidmain(String[]args){
 //TODOAuto-generatedmethodstub

 Filefile=null;

 InputStreamins=null;
 try{
 file=newFile("C:\\Test.java");

 ins=newFileInputStream(file);
 }catch(Exceptione){
 e.printStackTrace();
 }finally{
 IOUtils.closeQuietly(ins);
 }

 }

 }

文件复制

 publicclassFileCopyTest{

 /**
 *@paramargs
 */
 publicstaticvoidmain(String[]args)throwsException{
 //TODOAuto-generatedmethodstub

 Filesrcfile=newFile("c:\\Test.java");

 Filedestfile=newFile("c:\\Test.java.bak");


 FileUtils.copyFile(srcfile,destfile);

 }

 }

文件复制指定的目录

 publicclassFileCopyTest{

 /**
 *@paramargs
 */
 publicstaticvoidmain(String[]args)throwsException{
 //TODOAuto-generatedmethodstub

 Filesrcfile=newFile("c:\\Test.java");

 FiledestDir=newFile("D:\\");


 FileUtils.copyFileToDirectory(srcfile,destDir);

 }

 }

网络流保存为文件

 publicclassURLToFileTest{

 /**
 *@paramargs
 */
 publicstaticvoidmain(String[]args)throwsException{
 //TODOAuto-generatedmethodstub

 URLurl=newURL("http://www.163.com");

 Filefile=newFile("c:\\163.html");

 FileUtils.copyURLToFile(url,file);

 }

 }

文件目录操作

 publicclassDirOper{

 /**
 *@paramargs
 */
 publicstaticvoidmain(String[]args)throwsException{
 //TODOAuto-generatedmethodstub

 Filedir=newFile("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

 longsize=FileUtils.sizeOfDirectory(dir);

目录操作

 FiletestFile=newFile("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

 Filetest=newFile("test.dat");

 //输出流的统计
 CountingOutputStreamcountStream=null;

 //输入流的统计
 //CountingInputStreamcountStream=null;




 try{

 FileOutputStreamfos=newFileOutputStream(test);

 countStream=newCountingOutputStream(fos);

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

 }catch(IOExceptionioe){

 System.out.println("Errorwritingbytestofile.");

 }finally{

 IOUtils.closeQuietly(countStream);

 }



 if(countStream!=null){

 intbytesWritten=countStream.getCount();

 System.out.println("Wrote"+bytesWritten+"bytestotest.dat");

 }

相同的内容写入不同的文本

 Filetest1=newFile("split1.txt");

 Filetest2=newFile("split2.txt");

 OutputStreamoutStream=null;



 try{

 FileOutputStreamfos1=newFileOutputStream(test1);

 FileOutputStreamfos2=newFileOutputStream(test2);

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



 outStream.write("OneTwoThree,Test".getBytes());

 outStream.flush();

 }catch(IOExceptionioe){

 System.out.println("Errorwritingtosplitoutputstream");

 }finally{

 IOUtils.closeQuietly(outStream);

 }

转自:http://www.cnblogs.com/hellofei/archive/2010/04/10/1707131.html