io流读写及相关内容

列出某个目录下的所有文件：

File file = new File("e:\\总结");
File[] files = file.listFiles();
for(int i=0; i<files.length; i++){
 if(files[i].isFile()) System.out.println(files[i]);
}

列出某个目录下的所有子目录：

File file = new File("e:\\总结");
File[] files = file.listFiles();
for(int i=0; i<files.length; i++){
 if(files[i].isDirectory())
 System.out.println(files[i]);
}

如何读写文件，代码如下，有读取，复制，写入：

  1 public class ReadWriteCopy {
  2     public static void main(String args[]) {
  3         String from = "h:\\Android\\readtext.txt";
  4         String to = "h:\\Android\\writetext.txt";
  5         readline(from);
  6         copyText(from,to);
  7         writeText(to);
  8         //deletefile(from);
  9     }
 10
 11     public static void deletefile(String from){
 12         File fromFile=new File(from);
 13         if(fromFile.exists()){
 14             fromFile.delete();
 15         }
 16     }
 17     public static void readline(String from) {
 18         File fromFile = new File(from);
 19         BufferedReader reader=null;
 20         //FileReader fr=null;//可以用这个
 21         if (fromFile.exists()) {
 22             try {
 23                 //InputStreamReader isr=new InputStreamReader(new DataInputStream(new FileInputStream(fromFile)),"gb2312");
 24                 //或者
 25                 InputStreamReader isr=new InputStreamReader(new BufferedInputStream(new FileInputStream(fromFile),1024),"gb2312");
 26                 reader=new BufferedReader(isr);
 27                 List<users> userList=new ArrayList<users>();
 28                 String row="";
 29                 while ((row=reader.readLine()) != null) {
 30                     users u=new users();
 31                     String[] text=row.split(",");
 32                     u.setUserName(text[0]);
 33                     u.setUserId(text[1]);
 34                     u.setUserDate(text[2]);
 35                     userList.add(u);
 36                 }
 37                 for(users u:userList){
 38                     System.out.println("用户名："+u.getUserName()+"id:"+u.getUserId()+"date:"+u.getUserDate());
 39                 }
 40             }catch (IOException e1) {
 41                 // TODO Auto-generated catch block
 42                 e1.printStackTrace();
 43             }finally{
 44                 try {
 45                     reader.close();
 46                 } catch (IOException e) {
 47                     // TODO Auto-generated catch block
 48                     e.printStackTrace();
 49                 }
 50             }
 51         }
 52     }
 53
 54     public static void copyText(String from,String to){
 55         File fromFile = new File(from);
 56         File toFile = new File(to);
 57         BufferedInputStream fis=null;
 58         BufferedOutputStream fos=null;
 59         try {
 60             fis=new BufferedInputStream(new FileInputStream(fromFile));
 61             fos=new BufferedOutputStream(new FileOutputStream(toFile));
 62
 63             int num;
 64             while((num=fis.read())!=-1){
 65                 fos.write(num);
 66             }
 67         } catch (FileNotFoundException e) {
 68             // TODO Auto-generated catch block
 69             e.printStackTrace();
 70         } catch (IOException e) {
 71             // TODO Auto-generated catch block
 72             e.printStackTrace();
 73         }finally{
 74             try {
 75                 fis.close();
 76                 fos.close();
 77             } catch (IOException e) {
 78                 // TODO Auto-generated catch block
 79                 e.printStackTrace();
 80             }
 81         }
 82
 83     }
 84
 85     public static void writeText(String to){
 86         String text="往txt文件里写入该字符串";
 87         File toFile = new File(to);
 88         FileOutputStream fos=null;
 89         FileWriter fw=null;
 90         try {
 91             fos=new FileOutputStream(toFile);
 92             fos.write(text.getBytes());
 93
 94             fw=new FileWriter(toFile);
 95             fw.write(text);
 96         } catch (FileNotFoundException e) {
 97             // TODO Auto-generated catch block
 98             e.printStackTrace();
 99         } catch (IOException e) {
100             // TODO Auto-generated catch block
101             e.printStackTrace();
102         }
103     }
104 }