Other streams in Java classes and File IO package

File Deliverable (Package java.io)

　　For the operation of the class file.

　　Common methods: 1 Constructors:. Public  File ( String  pathname); // incoming file path and file name;

　　　　　　　2.public  boolean  isFile (); // determine whether the incoming path of the file;

　　　　　　　3.public boolean createNewFile () throws IOException; // create a file, if the file exists creation failed, and IO streams are not the same;

　　　　　　　4. public  Boolean  the isDirectory (); // determines whether the incoming path to the folder;

　　　　　　　5. public  boolean  mkdirs (); // create multi-level directory, if the directory exists creation fails;

　　　　　　　6. public  boolean  the Delete (); // delete failed return false;

　　　　　　　7. public  void  deleteOnExit (); // delete the specified file when the program exits;

　　　　　　　8. The public  Boolean  EXISTS (); // determine the file or folder exists;

Package second.study; 

Import java.io.BufferedWriter;
 Import java.io.File;
 Import java.io.FileWriter;
 Import java.io.IOException;
 Import of java.util.ArrayList;
 Import java.util.List; 

/ ** 
 * the absolute path of the folder stored in the specified file 
 * 
 * @param args
  * / 

public  class the Test { 

    public  static  void main (String [] args) throws IOException { 
        file the dir = new new file ( "F.: \\ \\ JAVA_study Code " ); 
        List <File> List =new new the ArrayList <File> ();
         IF (! dir.exists ()) {
             the throw  new new a RuntimeException ( "folder does not exist" ); 
        } 
        file2List (the dir, List); 
        File desFile = new new File (the dir, "dirname.txt " ); 
        list2File (List, desFile.toString ()); 
    } 

    / ** 
     * the content folder stored in the development of the collection 
     * 
     * @param dir 
     * @param List
      * / 
    public  static  void file2List (file dir, List <File> List) { 

        File [] Files= Dir.listFiles ();
         for (File File: Files) {
             IF (file.isDirectory ()) { 
                file2List (File, List); 
            } the else { 
                List.add (File); 
            } 
        } 
    } 

    / ** 
     * list the files stored in the specified file 
     * @param List 
     * @param desString
      * / 
    public  static  void list2File (List <file> List, String desString) { 
        BufferedWriter, BUFW = null ;
         the try  {
            BUFW= new BufferedWriter(new FileWriter(desString));
            for (File file : list) {
                bufw.write(file.getAbsolutePath());
                bufw.newLine();
                bufw.flush();
            }
        } catch (Exception ex) {
            throw new RuntimeException("目的地文件创建错误");
        } finally {
            try {
                if (bufw != null)
                    bufw.close();
            } catch(Exception EX) {
                 the throw  new new a RuntimeException ( "file close destination error" ); 
            } 
        } 
    } 
}

 Object stream (ObjectInputStream, ObjectOutputStream)

　　That is the object persistence

　　ObjectInputStream

　　Main method: 1 constructor: public  the ObjectInputStream ( the InputStream  in) throws IOException ; // stream associated with the object file;

　　　　　　　2. public Final Object readObject () throws IOException, ClassNotFoundException; // read the object file;

　　ObjectOutputStream

　　Main method: 1 constructor: public  the ObjectOutputStream ( the OutputStream  OUT) throws IOException ; // the stream associated with the object file;

　　　　　　　 2. public Final  void  the writeObject ( Object  obj) throws IOException ; // object is written to a file;

Package Penalty for second.study; 

Import the java.io.Serializable; 

public  class the Person the implements Serializable { 
    
//     current understanding: generally should not be covered, but will not cover the eclipse yellow exclamation mark. 
    Private  static  Final  Long serialVersionUID = 1L ;
     Private String name;
 //     if you do not want the value of other sequences can be used transient keyword. 
    transient  Private  int Age;
 //     now serialization methods zone data up? 
    static String Country = "CN" ;
     public the Person (String name, int Age, String Country) {
         Super();
        this.name = name;
        this.age = age;
        Person.country = country;
    }
    @Override
    public String toString() {
        return "Person [name=" + name + ", age=" + age + ", country=" + country + "]";
    }
    
}

package second.study;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

public class Test {

    public static void main(String[] args) throws Exception {

        writeObj();
        readObj();
    }

    public static void writeObj() throws Exception {
        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("obj.txt"));
        oos.writeObject(new Person("Zhangsan", 20, "kr"));
        oos.close();
    }

    public static void readObj() throws Exception {
        ObjectInputStream oin = new ObjectInputStream(new FileInputStream("obj.txt"));
        Person p = (Person)oin.readObject();
        oin.close();
        System.out.println(p);
    }
}

RandomAccessFile

　　This class is not a subclass of IO system, but directly inherit the Object class. But it is a member of the IO package, because it has to read and write methods. An array inside the package, can be operated by means by elements of the array for obtaining the getFilePointer position of the pointer () method , and can use the seek () method sets the position of the pointer .

　　Main methods: 1 Constructors:. Public  RandomAccessFile ( File  File, String  the MODE) throws FileNotFoundException ; // can only manipulate files, mode: "r", " rw", "rws", "rwd".

　　　　　　　2.构造函数：public RandomAccessFile​(String name, String mode) throws FileNotFoundException;

　　　　　　　3. public  Long  the getFilePointer () throws IOException ; // Get pointer location

　　　　　　　4. public  void  Seek ( Long POS) throws IOException ; // set the position of the pointer

　　　　　　　5. The public  int  the skipBytes ( int n-) throws IOException ; // number of bytes to skip, returns the number of bytes actually skipped

DataInputStream（java.io）

　　For operating the basic data types. The basic data types can be directly written to the file without having to convert the basic data types into bytes.