8.2学习笔记

知识点

1.TCP/IP

服务器server

public class MyServer {    public static void main(String[] args) {        try {            ServerSocket server = new ServerSocket(8080);            System.out.println("服务器启动");            Socket client = server.accept();            InputStream is = client.getInputStream();            BufferedReader br = new BufferedReader(new InputStreamReader(is));            OutputStream os = client.getOutputStream();            OutputStreamWriter osw = new OutputStreamWriter(os);            BufferedWriter bw = new BufferedWriter(osw);            String rWord;            Scanner scanner = new Scanner(System.in);            String tWord;            while(true){                rWord = br.readLine();                System.out.println(rWord);                tWord = scanner.next();                bw.write("褚文斌服务器："+tWord+"\n");                bw.flush();            }        } catch (IOException e) {            System.err.println("客户端已经关闭");        }    }}

客户端client

public class MyClient {    public static void main(String[] args) {        Socket client = null;        try {            client = new Socket("192.168.0.30", 8080);            System.out.println("客户端启动");            InputStream is = client.getInputStream();            BufferedReader br = new BufferedReader(new InputStreamReader(is));            OutputStream os = client.getOutputStream();            OutputStreamWriter osw = new OutputStreamWriter(os);            BufferedWriter bw = new BufferedWriter(osw);            Scanner scanner = new Scanner(System.in);            String tWord;            String rWold;            while(true){                tWord=scanner.next();                bw.write("褚文斌客户端："+tWord+"\n");                bw.flush();                rWold = br.readLine();                System.out.println(rWold);            }        } catch (UnknownHostException e) {            e.printStackTrace();        } catch (IOException e) {            System.out.println("服务器没有运行");        } finally {            try {                client.close();            } catch (IOException e) {                e.printStackTrace();            }        }    }}

UDP

接收方

public class UDPReceiver {    public static void main(String[] args) {        try {            DatagramSocket receiver = new DatagramSocket(8080, InetAddress.getLocalHost());            byte[] array = new byte[1024];            DatagramPacket packet = new DatagramPacket(array, 1024);            receiver.receive(packet);            System.out.println(new String(packet.getData()));            receiver.close();        } catch (SocketException e) {            e.printStackTrace();        } catch (UnknownHostException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }}

发送方

public class UDPSend {    public static void main(String[] args) {        try {            DatagramSocket send = new DatagramSocket();            String s = "你能接收到我吗";            byte[] array = s.getBytes();            DatagramPacket packet = new DatagramPacket(array,array.length, InetAddress.getLocalHost(), 8080);            System.out.println("正在发送数据...");            send.send(packet);            System.out.println("数据发送完毕");            send.close();        } catch (SocketException e) {            e.printStackTrace();        } catch (UnknownHostException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }}

集合

• 集合
  
  • collection
    
    • List
      
      • ArrayList
      • LinkedList（链表结构）
    • Set
      
      • HashSet
      • TreeSet
  • map
    
    • HashMap
    • TreeMap

ArrayList

    /*相对于LinkedList     *ArrayList遍历容易，添加、删除麻烦     *     */    List<String> list = new ArrayList<>();    list.add("李涛");//原第0个元素    list.add("李海萌");//原第1个元素    list.add("李大嘴");//原第2个元素    list.add(1, "陈冠希");//添加，后面依次后移一位。添加后是第1个元素    for(String m:list){        System.out.println(m);    }

Set

    /*     * Set 中不能放置重复的元素     * HashSet无序    TreeSet有序     */    Set<Integer> set = new HashSet<>();    Random random = new Random();    int count = 0;    while(count<10){        int num = random.nextInt(90)+10;        set.add(num);        System.out.println("放完第"+count+"个数:"+num);        count++;    }    System.out.println("已经放置完毕");    Iterator<Integer> it = set.iterator();//迭代器方法    while(it.hasNext()){        int i = it.next();        System.out.println(i);    }

Map

    Map<String, Student> map = new HashMap<>();    //第一个参数是键值对，第二个参数是被添加的内容    map.put("张三", new Student("张三"));    map.put("李四", new Student("李四"));    map.put(null, new Student("张王五"));    Set<String> keys = map.keySet();    //第一种方法    System.out.println("方法一：");    Iterator<String> it = keys.iterator();    while(it.hasNext()){        String key = it.next();        System.out.println(key+"||"+map.get(key).getName());    }    //第二种方法    System.out.println("方法二：");    for(String key:map.keySet()){        System.out.println(key+"||"+map.get(key).getName());    } 

Collections的排序方法sort()

    List<Student> list = new ArrayList<>();//尖括号里面的叫泛型    list.add(new Student("战三",19));    list.add(new Student("李四", 20));    list.add(new Student("王五", 23));    list.add(new Student("赵六", 21));    list.add(new Student("马奇", 18));    list.add(new Student("小明", 22));    Collections.sort(list, new StuComparator());//升序    Collections.reverse(list);//排列倒置    for(Student stu:list){        System.out.println(stu.getName()+"/"+stu.getAge());    }

泛类型

泛型方法的写法

public class Student<C,P extends Pet> {//可以给尖括号中的泛类型限定范围    private String name;    private int age;    private C clothes;//泛类型    private P p;    public C getClothes() {        return clothes;    }    public void setClothes(C clothes) {        this.clothes = clothes;    }    public P getP() {        return p;    }    public void setP(P p) {        this.p = p;    }    public Student(String name,int age，P p) {        this.name = name;        this.age = age;        this.p = p;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }}

随便写几个类充当泛型

public class Dog extends Pet{    public void bite(){        System.out.println("咬死你！");    }}

public class Cat extends Pet{    public void miao(){        System.out.println("喵喵喵");    }}

public class NanZhuang {}

public class NvZhuang {}

实现泛型方法的试例

public static void main(String[] args) {    //尖括号内的叫做泛型    Student<NanZhuang,Dog> xiaoming = new Student<>("小明", 19,new Dog());//此处只能填写Dog类，否则会出错    xiaoming.getP().bite();//用的是狗的方法    xiaoming.getClothes();//返回类型的女装    Student<NvZhuang, Cat> xiaohong = new Student<>("小红", 17,new Cat());    Cat cat = xiaohong.getP();    cat.miao();}