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();
}