第九节：详细讲解Java中的泛型，多线程，网络编程

拼搏现实的明天。 2021-09-15 03:36 305阅读 0赞

### 前言 ###

大家好，我是 `Vic`，今天给大家带来`详细讲解Java中的泛型，多线程，网络编程`的概述，希望你们喜欢

### 泛型 ###

泛型格式：ArrayList<Type> list= new ArrayList<Type>();  
ArrayList<Type> list= new ArrayList<>();  
Type可以为类，接口  
使用泛型可以使加入的，不用被强制

### 通配符 ###

ArrayList<? extends Type> list= new ArrayList<>();  
代表任意泛型

### 多线程 ###

在同一时间,做多件事情.

### 创建线程的方法 ###

继承类Thread并重写run()，run()称为线程体；用这种方法定义的类不能再继承其他类。

class FirstThread extends Thread{ public void run(){ for(int i=0;i<100;i++){ System.out.println("FirstThread"+i); } } } class Test{ public static void main(Sting args[]){ FirstThread ft = new FirstThread(); ft.start(); for(int i = 0; i<100;i++){ System.out.println("main"+i): } } }

### 接口Runnable的类作为线程的目标对象 ###

class Test implements Runnable{ public void run(){ for(int i = 0;i<100;i++){ System.out.println("Runnable"+i); } } } class Test{ public static void main(String args[]){ Test test = new Test(); Thread t = new Thread(test); System.out.println(t.getPriority()); t.start(); } }

### 中断线程 ###

Thread.sleep();  
Thread.yield();//让出自己正在使用的CPU

### 设置线程的优先级 ###

getPriority(); setPriority(); class Test implements Runnable{ public void run(){ for(int i = 0;i<100;i++){ System.out.println("Runnable"+i); if(i==50){ try{ Thread.sleep(2000); } catch(Exception e){ System.out.println(e); } } } } } class Test{ public static void main(String args[]){ RunnableImp1 ri = new RunnableImp1(); Thread t = new Thread(ri); t.setPriority(Thread.MAX_PRIORITY); //t.setPriority(Thread.MIN_PRIORITY); t.start(); System.out.println(t.getPriority()); } } class Test{ public static void main(String args[]){ MyThread myThread = new MyThread(); Thread t1 = new Thread(myThread); Thread t2 = new Thread(myThread); t1.setName("线程1"); t2.setName("线程2"); //分别启动 t1.start(); t2.start(); } } class MyThread implements Runnable{ int i = 100; public void run(){ while(true){ System.out.println(Thread.currentThread().getName()+i); i--; Thread.yield(); if(i<0){ break; } } } } //同步代码块 class MyThread implements Runnable{ int i = 100; public void run(){ while(true){ synchronized(this){ System.out.println(Thread.currentThread().getName()+i); i--; Thread.yield(); if(i<0){ break; } } } } } 深入synchronized关键字 class Service{ public void fun1(){ synchronized(this){ try{ Thread.sleep(3*1000); } catch(Exception e){ System.out.println("fun1"); } } public void fun2(){ synchronized(this){ System.out.println("fun2"); } } } class MyThread1 implements Runnable{ private Service service; public MyThread1(Service service){ this.service = service; } public void run(){ service.fun1(); } } class MyThread2 implements Runable{ private Service service; public MyThread2(Service service){ this.service = service; } public void run(){ service.fun2(); } } class Test{ public static void main(String args[]){ Service service = new Service(); Thread t1=new Thread(new MyThread1(service)); Thread t2=new Thread(new MyThread2(service)); t1.start(); t2.start(); } }

同步锁 锁住的是service  
同步方法，同步代码块锁住this

class Service{ public synchronized void fun1(){ try{ Thread.sleep(3*1000); } catch(Exception e){ System.out.println(e); } System.out.println("fun1"); } public void fun2(){ synchronized(this){ System.out.println("fun2"); } } } 数组 class Test{ public static void main(String args[]){ //数组的静态声明 int arr [] = { 5,2,7,8,9,0}; arr[3] = 10; //System.out.println(arr[3]); for(int i = 0;i<5;i++){ System.out.println(arr[i]); } } } class Test{ public static void main(String args[]){ int arr[] = { 2,4,6,7,8}; System.out.println(arr.length); } } 数组的动态声明 class Test{ public static void main(String args[]){ //动态声明 int arr [] = new int [10]; System.out.println("arr数组长度"+arr.length); for(int i = 0;i<arr.length;i++){ System.out.println(arr[i]); } } } 二维数组 class Test{ public static void main(String args[]){ //二维数组的定义方法，长度为3 int arr [][] = { { 1,2,3},{ 4,5,6},{ 7,8,9}}； System.out.println(arr[1][1]); for(int i = 0; i < 3; i++){ for(int j = 0; j < 3; j++){ System.out.println(arr[i][j]); } } } } 优化 class Test{ public static void main(String args[]){ //二维数组的定义方法，长度为3 int arr [][] = { { 1,2,3},{ 4,5,6},{ 7,8}}； System.out.println(arr[1][1]); for(int i = 0; i < arr.length; i++){ for(int j = 0; j < arr[i].length; j++){ System.out.println(arr[i][j]); } } } } 动态 class Test{ public static void main(String args[]){ //int arr [][] = { {1,2,3},{4,5,6},{7,8}}； int arr [][] = new int[3][5]; System.out.println(arr[1][1]); for(int i = 0; i < arr.length; i++){ for(int j = 0; j < arr[i].length; j++){ System.out.println(arr[i][j]); } } } }

线程概念  
进程：就是执行一个任务；  
线程：就是在进程内部同时做的事情。

## 网络开发Socket和ServerSocket ##

Socket为“孔”或“插座”，创建Socket，打开连接Socket的输入或输出流，对Socket进行读写，关闭Socket。

Accept方法用于产生“阻塞”，这里有getInputStream方法和getOutInputStream方法，会产生一个IOException，

在Java.net包中，有Socket和ServerSocket两个类。以JDK1.6介绍：

public Socket() public Socket(String host, int port) //host - 主机名，或者为 null，表示回送地址 //port - 端口号 public Socket(InetAddress address,int port) //address - IP 地址 //port - 端口号

ServerSocket(int port) ServerSocket(int port,int backlog) ServerSocket(int port,int backlog,InetAddress binAddr)

## 服务器与客户端通信 ##

package two; import java.io.DataInputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.PrintStream; import java.net.ServerSocket; import java.net.Socket; public class ServerSocket1 { public static void main(String[] args) { // TODO Auto-generated method stub try { ServerSocket ss = new ServerSocket(2007); while(true) { Socket s = ss.accept(); InputStream is = s.getInputStream(); OutputStream os = s.getOutputStream(); PrintStream ps = new PrintStream(os); ps.println("helloworld, i am server thinkpad"); DataInputStream dis = new DataInputStream(is); String str = dis.readLine(); System.out.println(str); s.close(); } } catch(IOException ee) { System.out.println(ee); } catch(Exception e) { System.out.println(e); } } }

package two; import java.io.DataInputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.PrintStream; import java.net.ConnectException; import java.net.Socket; public class ClientSocket { public static void main(String[] args) { // TODO Auto-generated method stub try { Socket s = new Socket("########",2007); InputStream is = s.getInputStream(); OutputStream os = s.getOutputStream(); PrintStream ps = new PrintStream(os); ps.println("hello , i am client"); DataInputStream dis = new DataInputStream(is); String str = dis.readLine(); System.out.println(str); s.close(); } catch(ConnectException eee) { System.out.println(eee); } catch(IOException ee) { System.out.println(ee); } catch(Exception e) { System.out.println(e); } } }

### 总结 ###

*  本文讲了详细讲解Java中的泛型，多线程，网络编程，如果您还有更好地理解，欢迎沟通
 *  定位：分享 `Android`&`Java`知识点，有兴趣可以继续关注