java服务器端编程基础入门

1、import java.awt.*;import java.awt.event.*;import .*;import java.io.*;public class ChatServer public static void main(String args) boolean started = false; / 判断服务器是否启动了，先假定没有启动ServerSocket ss = null;DataInputStream dis = null;try ss = new ServerSocket(8888);started = true; / 服务器已经启动了，设置started为truewh

2、ile (started) /当服务器端启动时。boolean bConnect = false; /判断服务器和客户端的连接是否已经建立， 没有为false，连接成功返回trueSocket s = ss.accept(); /accept()与readUTF()方法一样，都是一个阻塞式方法，如果没有收到连接请求，则一直等待。bConnect = true; /连接成功，设置bConnect为trueSystem.out.println(一个连接已经建立!); / -dis = new DataInputStream(s.getInputStream();while (bConnect) S

3、tring str = null;str = dis.readUTF(); /如果客户端突然断开连接,该语句就会抛出异常EOFException，所以我们必须得对dis.readUTF();进行异常处理/readUTF()是阻塞式方法，如果得不到数据，则继续等待，直到读取到数据为止System.out.println(从客户端接受的数据是: + str);catch (BindException e)System.out.println(端口已被占用，其使用其他端口);System.out.println(请关闭相关程序，重新运行!);System.exit(-1);catch (EOFExc

4、eption e)System.out.println(客户端已经断开连接!);catch (IOException e) /e.printStackTrace();System.out.println(服务器端读写错误!);finallytryif (null != ss) /如果监听程序打开了，则关闭网络监听程序ss.close();ss = null;if (null != dis) /如果输入流打开了，则关闭输入流dis.close();dis = null;catch (Exception e)class Aint divide(int a, int b)int m = 0;trym

5、 = a/b;catch (ArithmeticException e)System.out.printf(除数不能为零!n);/System.out.printf(1111);return m;public class TestExcep_1public static void main(String args)new A().divide(6, 2);/System.out.printf(2222);public class TestExcep_2public static void main(String args)int m = 99;trym = 2;System.out.print

6、f(m = %dn, m);catch (Exception e)System.out.printf(m = %dn, m);import java.util.Scanner;import java.util.InputMismatchException;public class TestExcep_3public static void main(String args)int i;Scanner sc = new Scanner(System.in); /System.in 表示键盘tryi = sc.nextInt();System.out.printf(i = %dn, i);catc

7、h (InputMismatchException e)System.out.printf(输入数据不合法，程序被终止!n);class Aint divide(int a, int b)return a/b;public void f()g();public void g()divide(6, 0);public class TestExcep_4public static void main(String args)trynew A().f();catch (Exception e)e.printStackTrace();import java.io.*;class Apublic voi

8、d f() throws IOException throw new IOException(); /throw 抛出异常public void g()throw new ArithmeticException();public class TestExcep_5public static void main(String args) /throws IOExceptionA aa = new A();tryaa.f();catch (IOException e)class Aint divide(int a, int b)int m = 0;m = a / b;return m;public

9、 class TestExcep_6public static void main(String args)trynew A().divide(6, 0);catch (Exception e)System.out.printf(嘿嘿n);e.printStackTrace();finallySystem.out.printf(好久啊哈n);import java.io.*;class DivisorIsZeroException extends Exceptionpublic DivisorIsZeroException(String name)super(name);class Apubl

10、ic int divide(int a, int b) throws DivisorIsZeroExceptionint m = 0;if (0 = b)throw new DivisorIsZeroException(除数不能为零! O(_)O哈哈);elsem = a/b;return m;public class TestExcep_7public static void main(String args) /throws IOExceptionA aa = new A();tryaa.divide(6, 0);catch (Exception e)e.printStackTrace()

11、;import java.io.*;class Apublic void f() throws ArithmeticException /throw new ArithmeticException(); /throw 抛出异常public class TestExcep_8public static void main(String args) /throws IOExceptionA aa = new A();tryaa.f();catch (ArithmeticException e)System.out.printf(haha );class Personpublic int age;p

12、ublic class TestNullPointerExceptionpublic static void main(String args) Person p = null;System.out.println(p.age);class DivisorIsZeroException extends Exceptionpublic DivisorIsZeroException(String errorMessage)super(errorMessage);class Aint divide(int a, int b) throws DivisorIsZeroException/try/if

13、(0 = b)/throw new DivisorIsZeroException(除数不能为零!);/catch (DivisorIsZeroException e)/e.printStackTrace();/if (0 = b)throw new DivisorIsZeroException(除数不能为零!);int m = a / b;return m;public class TestApublic static void main(String args)A aa = new A();/aa.divide(6, 2);/*2009年1月21日21:55:05子类覆盖了基类方法时，子类方

14、法抛出异常的范围不能大于基类方法抛出的异常范围子类方法可以不抛出异常，也可以只抛出基类方法的部分异常但不可以抛出基类方法以外的异常*/自定义异常Aclass A extends Exception/自定义异常Bclass B extends Exception/自定义异常Cclass C extends Exceptionclass Mvoid f() throws A, Bclass N extends Mvoid f() throws A,B /可以throws A或B,也可以throws A,B 也可以不throws，但不可以throws C 即子类覆盖了基类方法时，子类方法抛出异常的范

15、围不能大于基类方法抛出的异常范围class Testpublic void k(M mm)trymm.f();catch (A aa)catch (B bb)class TestExtendExcepublic static void main(String args)M m = new M();N n = new N();/System.out.println(1111);/*在JDK 1.6中的运行结果是：-1111-*/class A public String toString()return 哈哈;public class TestObjectpublic static void m

16、ain(String args)A aa = new A();System.out.printf(%sn, aa.toString();class Dianpublic int x, y;public Dian(int x, int y)this.x = x; this.y = y;public String toString()return + x + , + y + ; /3, 5public class TestPointpublic static void main(String args)Dian d = new Dian(3, 5);/System.out.printf(%s, d

17、);System.out.println(d);class Apublic void f()System.out.printf(AAAAn);class B extends Apublic void f()System.out.printf(BBBBn);public void g()public class TestPoly_1public static void main(String args)A aa = new A();B bb = new B();/aa = bb;aa.f();B bb2 = (B)aa;class Apublic int i;public A(int i)thi

18、s.i = i;/public boolean equals(Object obj)/A aa = (A)obj;/if(this.i = aa.i) /if (当前对象的i和obj代表的i相等)/return true;/else/return false;/public class TestStringEquals_2public static void main(String args)A aa1 = new A(2);A aa2 = new A(2);System.out.println( aa1.equals(aa2) ); /true/*2009年3月14日9:34:11先catch子类异常再catch父类异常如果先catch父类异常再catch子类异常，则编译时会报错*/class A extends Exceptionclass B ex