1. Flow Summary and demonstration cases
The input stream and the output stream are relative to the memory device.
Read data from peripherals into memory: input
Writes the number of memory to the peripheral: output.
The origin of the character stream:
Actually is: The byte stream reads the literal bytes data, does not direct operation but first checks the specified encoding table. Gets the corresponding text.
The text is being manipulated. Simple: Byte stream + encoding table
Two top-level parent class for byte stream:
1,inputstream 2,outputstream.
Two top-level parent classes of character streams:
1,reader 2,writer
String FilePath = "F:\\demo.txt";
FileWriter fw = new FileWriter (filepath,true);
/*
* writes the data by calling the write (string) method in the writer object.
*
* The data is actually written to the temporary storage buffer.
*
*/
Fw.write ("Abcdehahaha");
Fw.write ("Xixi");
/*
* Refreshes to write the data directly to the destination.
*/
Fw.flush ();
//1, creating a stream object that reads character data.
/*
* When you create a read stream object, you must explicitly read the file. Be sure that the file exists.
*
* Associates an existing file with a read stream.
*/
FileReader fr = new FileReader ("Demo.txt");
The first method reads
//int CH3 = 0;
while ((Ch3=fr.read ())!=-1) {//Use the Read () loop to read the
//system.out.print ((char) CH3) by a character-by-string;
}
//Second way read
//char[] buf = new char[1024];
int len = 0;
//while ((Len=fr.read (BUF))!=-1) {
//system.out.println (new String (Buf,0,len));
}
//Third Way read
BufferedReader bufr = new BufferedReader (FR);
String line = null;
while ((Line=bufr.readline ())!=null) {
System.out.println (line);
}
Fr.close ();
2. Use buffer method to read and write files
Read demo, write Demowrite
String Readfilepath = "F:\\demo.txt";
String Writefilepath = "F:\\demowrite.txt";
FileReader FR = new FileReader (Readfilepath);
BufferedReader bufr = new BufferedReader (FR);
FileWriter FW = new FileWriter (Writefilepath);
BufferedWriter BUFW = new BufferedWriter (FW);
String line = null;
while (line = Bufr.readline ()) = null) {
Bufw.write (line);
Bufw.newline ();
Bufw.flush ();
}
Bufw.close ();
Bufr.close ();
3.LineNumberReader
String Readfilepath = "F:\\demo.txt";
FileReader FR = new FileReader (Readfilepath);
LineNumberReader LNR = new LineNumberReader (FR);
String line = Null;//linenumberreader has a function more than BufferedReader, which is to return the current row number. In addition Setlinenumber can change the line number, but can not change the position of reading.
Lnr.setlinenumber (1);//getlinenumber () The line number shown will start at 2
while ((Line=lnr.readline ())!=null) {
System.out.println (Lnr.getlinenumber () + ":" +line);
}
Lnr.close ();
Use of 4.File class objects
File File = new file ("f:\\");
System.out.println ("Getfreespace:" +file.getfreespace ());//Get the remaining space of the F-disk
System.out.println ("Gettotalspace:" +file.gettotalspace ());
System.out.println ("Getusablespace:" +file.getusablespace ());
//
file[] files = file.listroots ();//Get the computer's disk
//
for (File file2:files) {
//
System.out.println (file2);
//
}
Rename, rename Demo.txt to Demowrite1
File F1 = new file ("F:\\demo.txt");
File F2 = new file ("F:\\demowrite1.txt");
Boolean B = F1.renameto (F2);
System.out.println ("b=" +b);
The creation and deletion of files.
File File = new file ("F:\\file.txt");
/*
* Unlike the output stream, if the file does not exist, it is created and is not created if the file exists.
*/
//
Boolean B = File.createnewfile ();
System.out.println ("b=" + b);
FileWriter writer = new FileWriter (file);
Writer.write ("AAA");
Writer.flush ();
Writer.close ();
Boolean B1 = File.delete ();
System.out.println ("b1=" + B1);
5.Serializable Marking interface
Serializable: Used to add an ID number to the class being serialized.
Used to determine if a class and an object are the same version.
public class Person implements Serializable {
/**
* Transient: Non-static data does not want to be serialized can be modified with this keyword.
*/
Private static final long serialversionuid = 9527l;
private transient String name;
private static int age;
Public person (String name, int age) {
THIS.name = name;
This.age = age;
}
Public String GetName () {
return name;
}
public void SetName (String name) {
THIS.name = name;
}
public int getage () {
return age;
}
public void Setage (int.) {
This.age = age;
}
}
ObjectOutputStream oos = new ObjectOutputStream (New FileOutputStream ("Obj.object"));
The serialization of the object. The serialized object must implement the Serializable interface.
Oos.writeobject (New Person ("Xiao Qiang", 30));
Oos.close ();
ObjectInputStream ois = new ObjectInputStream (New FileInputStream ("Obj.object"));
The deserialization of the object.
Person P = (person) ois.readobject ();
System.out.println (P.getname () + ":" + p.getage ());
Ois.close ();
A brief description of Java Basic Learning flow and demonstration case, buffer method to read and write files, use of File class object, serializable Tag interface (6)