import java.io.*;
class Person implements Serializable
{
public static final long serialVersionUID = 42L;//自己定义固定的UID,给类一个固定标识,
private String name;
transient int age;//保证其值在堆内存中存在,不被序列化【不再txt中存在】
static String country = "cn";//静态不能被序列化
Person(String name,int age,String country)
{
this.name = name;
this.age = age;
this.country = country;
}
public String toString()
{
return name+":"+age+":"+country;
}
}
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import java.io.*;
class ObjectStreamDemo
{
public static void main(String[] args) throws Exception
{
//writeObj();
readObj();
}
public static void readObj()throws Exception
{
ObjectInputStream ois = new ObjectInputStream(new FileInputStream("obj.txt"));
Person p = (Person)ois.readObject();
System.out.println(p);
ois.close();
}
public static void writeObj()throws IOException
{
ObjectOutputStream oos =
new ObjectOutputStream(new FileOutputStream("obj.txt"));
oos.writeObject(new Person("lisi0",399,"kr"));
oos.close();
}
}
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import java.io.*;
class Read implements Runnable
{
private PipedInputStream in;
Read(PipedInputStream in)
{
this.in = in;
}
public void run()
{
try
{
byte[] buf = new byte[1024];
System.out.println("读取前。。没有数据阻塞");
int len = in.read(buf);
System.out.println("读到数据。。阻塞结束");
String s= new String(buf,0,len);
System.out.println(s);
in.close();
}
catch (IOException e)
{
throw new RuntimeException("管道读取流失败");
}
}
}
class Write implements Runnable
{
private PipedOutputStream out;
Write(PipedOutputStream out)
{
this.out = out;
}
public void run()
{
try
{
System.out.println("开始写入数据,等待6秒后。");
Thread.sleep(6000);
out.write("piped lai la".getBytes());
out.close();
}
catch (Exception e)
{
throw new RuntimeException("管道输出流失败");
}
}
}
class PipedStreamDemo
{
public static void main(String[] args) throws IOException
{
PipedInputStream in = new PipedInputStream();
PipedOutputStream out = new PipedOutputStream();
in.connect(out);
Read r = new Read(in);
Write w = new Write(out);
new Thread(r).start();
new Thread(w).start();
}
}
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import java.io.*;
/*
RandomAccessFile
该类不是算是IO体系中子类。
而是直接继承自Object。
但是它是IO包中成员。因为它具备读和写功能。
内部封装了一个数组,而且通过指针对数组的元素进行操作。
可以通过getFilePointer获取指针位置,
同时可以通过seek改变指针的位置。
其实完成读写的原理就是内部封装了字节输入流和输出流。
通过构造函数可以看出,该类只能操作文件。
而且操作文件还有模式:只读r,,读写rw等。
如果模式为只读 r。不会创建文件。会去读取一个已存在文件,如果该文件不存在,则会出现异常。
如果模式rw。操作的文件不存在,会自动创建。如果存在则不会覆盖。
*/
class RandomAccessFileDemo
{
public static void main(String[] args) throws IOException
{
//writeFile();
//writeFile_2();
//readFile();
//System.out.println(Integer.toBinaryString(258));
}
public static void readFile()throws IOException
{
RandomAccessFile raf = new RandomAccessFile("ran.txt","r");
//调整对象中指针。
//raf.seek(8*1);//读取第二个人//寻找第八位--读取王五//一个人姓名+年龄=8字节----读取第n个人--8*n
//跳过指定的字节数
raf.skipBytes(8);//为了读下一个--向下跳8个字节
byte[] buf = new byte[4];
raf.read(buf);
String name = new String(buf);
int age = raf.readInt();
System.out.println("name="+name);
System.out.println("age="+age);
raf.close();
}
public static void writeFile_2()throws IOException//重点掌握!!!!!----多线程下载!
{
RandomAccessFile raf = new RandomAccessFile("ran.txt","rw");
raf.seek(8*0);
raf.write("周期".getBytes());
raf.writeInt(103);
raf.close();
}
public static void writeFile()throws IOException
{
RandomAccessFile raf = new RandomAccessFile("ran.txt","rw");//读写模式
raf.write("李四".getBytes());
//raf.write();//结果:a
raf.writeInt(97);//写入整型--结果:三个空格+a【共四个字节】
raf.write("王五".getBytes());
raf.writeInt(99);
raf.close();
}
}
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/*
DataInputStream与DataOutputStream
可以用于操作基本数据类型的数据的流对象。
*/
import java.io.*;
class DataStreamDemo
{
public static void main(String[] args) throws IOException
{
//writeData();
//readData();
//writeUTFDemo();
//转换流----//"utf.txt"
//OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream("gbk.txt"),"gbk");
//
//osw.write("你好");
//osw.close();
readUTFDemo();
}
public static void readUTFDemo()throws IOException//只能这样读utf
{
DataInputStream dis = new DataInputStream(new FileInputStream("utfdate.txt"));//结果:你哈
//DataInputStream dis = new DataInputStream(new FileInputStream("utf.txt"));//结果:出现异常!
String s = dis.readUTF();
System.out.println(s);
dis.close();
}
public static void writeUTFDemo()throws IOException
{
DataOutputStream dos = new DataOutputStream(new FileOutputStream("utfdate.txt"));
dos.writeUTF("你好");
dos.close();
}
public static void readData()throws IOException
{
DataInputStream dis = new DataInputStream(new FileInputStream("data.txt"));
int num = dis.readInt();
boolean b = dis.readBoolean();
double d = dis.readDouble();
System.out.println("num="+num);
System.out.println("b="+b);
System.out.println("d="+d);
dis.close();
}
public static void writeData()throws IOException
{
DataOutputStream dos = new DataOutputStream(new FileOutputStream("data.txt"));
dos.writeInt(234);
dos.writeBoolean(true);
dos.writeDouble(9887.543);
dos.close();
//ObjectOutputStream oos = null;
//oos.writeObject(new O());
}
}
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/*
用于操作字节数组的流对象。
ByteArrayInputStream :在构造的时候,需要接收数据源,。而且数据源是一个字节数组。
ByteArrayOutputStream: 在构造的时候,不用定义数据目的,因为该对象中已经内部封装了可变长度的字节数组。
这就是数据目的地。
因为这两个流对象都操作的数组,并没有使用系统资源。
所以,不用进行close关闭。
在流操作规律讲解时:
源设备,
键盘 System.in,硬盘 FileStream,内存 ArrayStream。
目的设备:
控制台 System.out,硬盘FileStream,内存 ArrayStream。
用流的读写思想来操作数据。
*/
import java.io.*;
class ByteArrayStream
{
public static void main(String[] args)
{
//数据源。
ByteArrayInputStream bis = new ByteArrayInputStream("ABCDEFD".getBytes());
//数据目的
ByteArrayOutputStream bos = new ByteArrayOutputStream();
int by = 0;
while((by=bis.read())!=-1)
{
bos.write(by);
}
System.out.println(bos.size());
System.out.println(bos.toString());
//bos.writeTo(new FileOutputStream("a.txt"));
}
}
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import java.io.*;
class EncodeStream
{
public static void main(String[] args) throws IOException
{
//writeText();
readText();
}
public static void readText()throws IOException
{
InputStreamReader isr = new InputStreamReader(new FileInputStream("utf.txt"),"gbk");
char[] buf = new char[10];
int len = isr.read(buf);
String str = new String(buf,0,len);
System.out.println(str);
isr.close();
}
public static void writeText()throws IOException
{
OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream("utf.txt"),"UTF-8");
osw.write("你好");
osw.close();
}
}
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/*
编码:字符串变成字节数组。
解码:字节数组变成字符串。
String-->byte[]; str.getBytes(charsetName);
byte[] -->String: new String(byte[],charsetName);
*/
import java.util.*;
class EncodeDemo
{
public static void main(String[] args)throws Exception
{
String s = "哈哈";
byte[] b1 = s.getBytes("GBK");
System.out.println(Arrays.toString(b1));
String s1 = new String(b1,"utf-8");
System.out.println("s1="+s1);
//对s1进行iso8859-1编码。
byte[] b2 = s1.getBytes("utf-8");
System.out.println(Arrays.toString(b2));
String s2 = new String(b2,"gbk");
System.out.println("s2="+s2);
}
}
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class EncodeDemo2
{
public static void main(String[] args) throws Exception
{
String s = "��ͨ";
byte[] by = s.getBytes("gbk");
for(byte b : by)
{
System.out.println(Integer.toBinaryString(b&255));
}
System.out.println("Hello World!");
}
}
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/*
有五个学生,每个学生有3门课的成绩,
从键盘输入以上数据(包括姓名,三门课成绩),
输入的格式:如:zhagnsan,30,40,60计算出总成绩,
并把学生的信息和计算出的总分数高低顺序存放在磁盘文件"stud.txt"中。
1,描述学生对象。
2,定义一个可操作学生对象的工具类。
思想:
1,通过获取键盘录入一行数据,并将该行中的信息取出封装成学生对象。
2,因为学生有很多,那么就需要存储,使用到集合。因为要对学生的总分排序。
所以可以使用TreeSet。
3,将集合的信息写入到一个文件中。
*/
import java.io.*;
import java.util.*;
class Student implements Comparable<Student>
{
private String name;
private int ma,cn,en;
private int sum;
Student(String name,int ma,int cn,int en)
{
this.name = name;
this.ma = ma;
this.cn = cn;
this.en = en;
sum = ma + cn + en;
}
public int compareTo(Student s)
{
int num = new Integer(this.sum).compareTo(new Integer(s.sum));
if(num==0)
return this.name.compareTo(s.name);
return num;
}
public String getName()
{
return name;
}
public int getSum()
{
return sum;
}
public int hashCode()
{
return name.hashCode()+sum*78;
}
public boolean equals(Object obj)
{
if(!(obj instanceof Student))
throw new ClassCastException("类型不匹配");
Student s = (Student)obj;
return this.name.equals(s.name) && this.sum==s.sum;
}
public String toString()
{
return "student["+name+", "+ma+", "+cn+", "+en+"]";
}
}
class StudentInfoTool
{
public static Set<Student> getStudents()throws IOException
{
return getStudents(null);
}
public static Set<Student> getStudents(Comparator<Student> cmp)throws IOException
{
BufferedReader bufr =
new BufferedReader(new InputStreamReader(System.in));
String line = null;
Set<Student> stus = null;
if(cmp==null)
stus = new TreeSet<Student>();
else
stus = new TreeSet<Student>(cmp);
while((line=bufr.readLine())!=null)
{
if("over".equals(line))
break;
String[] info = line.split(",");
Student stu = new Student(info[0],Integer.parseInt(info[1]),
Integer.parseInt(info[2]),
Integer.parseInt(info[3]));
stus.add(stu);
}
bufr.close();
return stus;
}
public static void write2File(Set<Student> stus)throws IOException
{
BufferedWriter bufw = new BufferedWriter(new FileWriter("stuinfo.txt"));
for(Student stu : stus)
{
bufw.write(stu.toString()+"\t");
bufw.write(stu.getSum()+"");
bufw.newLine();
bufw.flush();
}
bufw.close();
}
}
class StudentInfoTest
{
public static void main(String[] args) throws IOException
{
Comparator<Student> cmp = Collections.reverseOrder();
Set<Student> stus = StudentInfoTool.getStudents(cmp);
StudentInfoTool.write2File(stus);
}
}
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/*
猜数字游戏:
1,产生随机数。
2,获取键盘录入。
3,将录入数据变成数字,和随机数比较。
给出提示信息。
4,重复这个过程,如果猜中,程序就结束。
注意:对于输入1~100以外的数字,,以及非数字要给出提示。
*/
import java.io.*;
import java.util.*;
class GuessNumber
{
private int ranNum;
GuessNumber()
{
Random r = new Random();
ranNum = r.nextInt(100)+1;//(int)Math.random()*100+1;
}
public void play()
{
System.out.println("游戏开始:输入1~100之间的数字:");
boolean b = false;
while(!b)
{
try
{
int num = getNum();
if(num>=1 && num<=100)
b = isLuck(num);
else
System.out.println("数值超出范围");
}
catch (IOException e)
{
throw new RuntimeException("录入数据失败");
}
catch(NumberFormatException e)
{
System.out.println("输入了非法数据");
}
}
}
//获取键盘的数字
private int getNum()throws IOException,NumberFormatException
{
BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));
int num = Integer.parseInt(bufr.readLine());
return num;
}
//和随机数比较
private boolean isLuck(int num)
{
boolean b = false;
if(num>ranNum)
System.out.println("大了,继续");
else if(num<ranNum)
System.out.println("小了,继续");
else
{
System.out.println("中了,恭喜");
b = true;
}
return b;
}
}
class GuessNumberDemo
{
public static void main(String[] args)
{
new GuessNumber().play();
}
}