io流的学习4-编程知识

io流的学习4

字符缓冲流

原理：底层自带了长度为8192的缓冲区提高性能。

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;public class BufferedStringdemo01 {public static void main(String[] args) throws IOException {BufferedReader br=new BufferedReader(new FileReader("F:\\javaEE\\src\\MyCharset\\a.txt"));/*String s = br.readLine();System.out.println(s);*/String line;while((line=br.readLine())!=null){System.out.println(line);}br.close();}
}

package MyCharset;import java.io.*;public class BufferedStringdemo02 {public static void main(String[] args) throws IOException {BufferedWriter bw=new BufferedWriter(new FileWriter("F:\\javaEE\\src\\MyCharset\\a.txt"));bw.write("hhhhhhhh");bw.newLine();bw.write("aaaaaaa");bw.newLine();bw.close();}
}

转换流

是字符流和字节流之间的桥梁。

package myConvertstream;import java.io.*;public class mydemo01 {public static void main(String[] args) throws IOException {InputStreamReader isr=new InputStreamReader(new FileInputStream("myio\\gbkfile.txt"),"GBK") ;int ch;while((ch=isr.read())!=-1){System.out.println((char)ch);}isr.close();}
}

package myConvertstream;import java.io.*;
import java.nio.charset.Charset;public class mydemo01 {public static void main(String[] args) throws IOException {
/*   int ch;while((ch=isr.read())!=-1){System.out.println((char)ch);}isr.close();*/FileReader fr=new FileReader("myio\\gbkfile.txt", Charset.forName("GBK"));int ch;while((ch=fr.read())!=-1){System.out.println((char)ch);}fr.close();}
}

package myConvertstream;import java.io.*;public class mcdemo01 {public static void main(String[] args) throws IOException {OutputStreamWriter osw=new OutputStreamWriter(new FileOutputStream("myio\\b.txt"),"GBK");osw.write("hellohello");osw.close();}
}

package myConvertstream;import java.io.*;public class mcdemo02 {public static void main(String[] args) throws IOException {/*将本地GBK文件转换成UTF-8*///jdk11以前的方案InputStreamReader isr=new InputStreamReader(new FileInputStream("myio\\b.txt"),"GBK");OutputStreamWriter osw=new OutputStreamWriter(new FileOutputStream("myio\\d.txt"),"UTF-8");int b;while((b=isr.read())!=-1){osw.write(b);}osw.close();isr.close();}
}

package myConvertstream;import java.io.*;public class mcdemo03 {public static void main(String[] args) throws IOException {/*利用字节流读取文件中的数据，每次读一整行，而且不能出现乱码*/FileInputStream fis=new FileInputStream("myio\\a.txt");InputStreamReader isr=new InputStreamReader(fis);BufferedReader br=new BufferedReader(isr);String s = br.readLine();System.out.println(s);br.close();}
}

序列化流

可以把JAVA中的对象写到本地文件中。

import java.io.Serializable;public class Student implements Serializable {private int age;private String name;public Student() {}public Student(int age, String name) {this.age = age;this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}@Overridepublic String toString() {return "Student{" +"age=" + age +", name='" + name + '\'' +'}';}
}

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;public class odemo01 {public static void main(String[] args) throws IOException {
Student stu=new Student(24,"karry");ObjectOutputStream oos=new ObjectOutputStream(new FileOutputStream("myio\\a.txt"));oos.writeObject(stu);oos.close();}
}

反序列化流

可以把序列化到本地文件中的对象，读取到程序中来。

package myConvertstream;import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.ObjectInputStream;public class odemo02 {public static void main(String[] args) throws IOException, ClassNotFoundException {ObjectInputStream ois=new ObjectInputStream(new FileInputStream("myio\\a.txt"));Object o = ois.readObject();System.out.println(o);ois.close();}
}