黑马程序员——Java基础——IO流(下)

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IO流(下)
其他相关流

如图



1.FIle文件类

用于操作文件的类,详情请查看API

2.打印流

1)PrintStream (字节)

2)PrintWriter(字符)

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.io.PrintWriter;

class PrintDemo
{
public static void main(String[] args) throws Exception{
//输入
//BufferedInputStream cin = new BufferedInputStream(System.in);
BufferedReader cin = new BufferedReader(new InputStreamReader(System.in));
//字符输出流
PrintWriter out = new PrintWriter("a.txt");
//字节输出流
//PrintStream out = new PrintStream("a.txt");
String line = null;
while((line = cin.readLine())!=null){
out.println(line);
out.flush();

}
out.close();
cin.close();
}
}

3.管道流

import java.io.*;
//建议多线程
//读取
class Read implements Runnable
{
private PipedInputStream in;
Read(PipedInputStream in){
this.in = in;
}
public void run(){
try{
byte[] buf = new byte[1024];

int len = in.read(buf);

String s = new String(buf ,0,len);
System.out.println(s);
in.close();
}catch(Exception e){
}
}
}
//写入
class Write implements Runnable
{
private PipedOutputStream out;
Write(PipedOutputStream out){
this.out = out;
}
public void run(){
try{

out.write("管道".getBytes());
out.close();
}catch(Exception e){
}
}
}

class PipedIODemo
{
public static void main(String[] args) throws IOException{
PipedInputStream in = new PipedInputStream();
PipedOutputStream out = new PipedOutputStream();
in.connect(out);

Thread t1 = new Thread(new Read(in));
Thread t2 = new Thread(new Write(out));
t1.start();
t2.start();
}
}

4.序列流(合并流)

import java.io.*l
import java.util.*;

class SequenceInputStreamDemo
{
public static void main(String[] args) throws IOException {
//	File f = new File("e:");
//建立文件输入集合
Vector<FileInputStream> v = new Vector<FileInputStream>();
//输入文件
v.add("1.txt");
v.add("2.txt");
//获取文件
Enumeration<FileInputStream> en = v.elements();
//合并流
SequenceInputStream sis = new SequenceInputStream(en);
//合并后文件
FileOutputStream fos = new FileOutputStream("4.txt");

byte[] buf = new byte[1024];
int len = 0;
//合并操作
while((len = sis.read(buf))!=-1){
fos.write(buf,0,len);
}
fos.close();
sis.close();

}
}

5.对象序列化流

import java.io.*;

//准备写入的对象,必须实现Serializable接口,标记接口
class Student implements Serializable
{

public static final long serialVersionUID = 1L;//如果类发生改变,只要ID不变,默认为一个类

private String name;
transient private int age;//transient参数,有的话,就不写入
Student(String name ,int age){
this.name = name;
this.age = age;
}
public String toString(){
return name+"  "+age;
}
}

class ObjectIODemo
{
public static void main(String[] args) throws Exception{
//读取
//ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("Object.txt"));
//oos.writeObject(new Student("xiaoming",22));
//oos.close();
//输入
ObjectInputStream ois = new ObjectInputStream(new FileInputStream("Object.txt"));
Student p = (Student)ois.readObject();
System.out.println(p);
ois.close();
}
}

输入输出重定向
System类中的字段：in，out,是标准输入输出,默认的话是输入时键盘,输出是显示器

System.in的类型是InputSteam

System.out的类型是PrintSteam

1.输入重定向

import java.io.FileInputStream;

import java.io.IOException;

public class SystemIn {
//没处理异常
public static void main(String[] args) throws IOException {
//重定向输入,从文件输入
System.setIn(new FileInputStream("aa.txt"));
byte buff[] = new byte [1024];
int len = 0;
String str = null;
while((len=System.in.read(buff))!=-1){
str += new String(buff, 0, len);
}
System.out.println(str);
}
}

2.输出重定向

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.PrintStream;

public class SystemOut {
//没处理异常
public static void main(String[] args) throws FileNotFoundException {
//设置输出
System.setOut(new PrintStream(new FileOutputStream("out.txt")));
String str = "测试实验";
System.out.println(str);
}
}

三种键盘录入方式

A:main方法的args接收参数

B:System.in通过BufferedReader进行包装

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

C:Scanner

Scanner sc = new Scanner(System.in);