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JAVA常用函数

字符串转列表

String ids = "1,2,3,4,5";
List<Integer> idsList = Arrays.stream(ids.split(",")).map(s -> Integer.parseInt(s.trim())).collect(Collectors.toList());

时间戳转日期格式

Long createdEnd = createTime;/毫秒时间戳
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
System.out.println(simpleDateFormat.format(createTime));

递归删除文件夹

public static void main(String[] args){
  File path = new File("/Users/Jeffrey/Desktop/willdelete");
  /递归删除
  boolean res = deletePath(path);
  if(res) System.out.println("success");
}

 private static boolean deletePath(File path) {
        if (path.exists()){
            File[] files = path.listFiles();
            assert files != null;
            for (File file : files) {
                if (file.isFile()){
                    /直接删除
                    file.delete();
                }else{
                    /如果是文件夹  继续打开文件夹，判断有没有文件
                    deletePath(file);
                }
            }
            return path.delete();
        }
        return true;
    }

文件写入

fileOutputStream(byte,boolean append)
fileOutputStream(byre[],boolean append)
/换行  "\r\n".getBytes()
FileOutputStream fileOutputStream = null;
try {
  fileOutputStream = new FileOutputStream("/Users/Jeffrey/Desktop/TTT.txt");
  fileOutputStream.write(99);
  fileOutputStream.close();
}catch (Exception e){
  e.printStackTrace();
}finally {
  if (fileOutputStream != null){
    try {
      fileOutputStream.close();
    }catch (Exception e){
      e.printStackTrace();
    }
  }
}

并行和并发、进程和线程

第一种开启线程

public class MyThread extends Thread{
    private String title;
    public MyThread(String title) {
        this.title = title;
    }

    @Override
    public void run(){
        for (int i = 0; i < 100; i++) {
            System.out.println(this.title + "开启了线程" + i);
        }
    }
}
/开启线程
MyThread myThread = new MyThread("Test1");
MyThread myThread1 = new MyThread("Test2");
myThread.start();
myThread1.start();

第二种开启线程【Runnable】

public class MyRunnable implements Runnable{
    @Override
    public void run() {
        for (int i = 0; i < 100; i++) {
            System.out.println("第二种方式开启线程 " + i);
        }
    }
}
/开启线程
MyRunnable myRunnable = new MyRunnable();
Thread thread = new Thread(myRunnable);
thread.start();

第三种看起线程【Callable和Future】

优点
- 扩展性强，实现该接口的同时可以继承其他的类
缺点
- 编程相对复杂，不能直接使用Thread类

public class MyCallable implements Callable<String> {
    @Override
    public String call() throws Exception {
        //返回值表示线程执行结束之后的返回结果
        for (int i = 0; i < 100; i++) {
            System.out.println("第三种开启下线程 " + (i + 1));
        }
        return "执行结束";
    }
}
//开启线程
MyCallable myCallable = new MyCallable();
FutureTask<String> stringFutureTask = new FutureTask<>(myCallable);
Thread thread1 = new Thread(stringFutureTask);
thread1.start();
String s = stringFutureTask.get();
System.out.println(s);

生产者、消费者

消费者

package cn.zhangfayuan.collection;

public class Eater extends Thread{
    @Override
    public void run() {
        while (true){
            synchronized (TableDesk.lock){
                if (TableDesk.count == 0){
                    break;
                }else{
                    if (TableDesk.flag){
                        System.out.println("消费者消费");
                        TableDesk.flag = false;
                        TableDesk.lock.notifyAll();
                        TableDesk.count--;
                    }else{
                        try {
                            TableDesk.lock.wait();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
    }
}

生产者

package cn.zhangfayuan.collection;


public class Cooker extends Thread{
    @Override
    public void run() {
        while (true){
            synchronized (TableDesk.lock){
                if (TableDesk.count == 0){
                    break;
                } else {
                   if (TableDesk.flag){
                       //有数据 就等待
                       try {
                           TableDesk.lock.wait();
                       } catch (InterruptedException e) {
                           e.printStackTrace();
                       }
                   }else{
                       //生产
                       System.out.println("生产者生产");
                       TableDesk.flag = true;
                       TableDesk.lock.notifyAll();
                   }
                }
            }
        }
    }
}

中间作用类

package cn.zhangfayuan.collection;

public class TableDesk {

    public static int count = 10;
    public static boolean flag = false;
    public static final Object lock  = new Object();


}

调用

Eater eater = new Eater();
Cooker cooker = new Cooker();
eater.start();
cooker.start();

//======================  处理结果   ==================
//生产者生产
//消费者消费
//生产者生产
//消费者消费
//生产者生产
//消费者消费
//生产者生产
//消费者消费
//生产者生产
//消费者消费
//生产者生产
//消费者消费
//生产者生产
//消费者消费
//生产者生产
//消费者消费
//生产者生产
//消费者消费 
//生产者生产
//消费者消费

redis-cli -h redis-k268b7ibip3s-proxy-nlb.jvessel-open-hb.jdcloud.com -p 6379 -a 4jq1QdugammK

zip

持枪

1.png

2.png

3.png

持棍

1.png

4.png

5.png

持刀

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