多线程打印字符

╰半夏微凉° 2022-09-22 15:51 190阅读 0赞

写了一个多线程的打印，如一个线程打印12345，另一个线程打印ABCDE，最后结果是1A2B3C4D5E。

以下是代码及部分测试结果：

打印客户端类：PrinterCilent

package com.syz.thread.print;
    
    public class PrinterCilent {
        public static void main(String[] args) {
            String s1 = "1234567890";
            String s2 = "abcdefghij";
            String s3 = "ABCDEFGHIJ";
    
            Printer p = new Printer();
    
            Thread t1 = new PrinterThread(p, s1);
            Thread t2 = new PrinterThread(p, s2);
            Thread t3 = new PrinterThread(p, s3);
    
            t1.start();
            t2.start();
            t3.start();
        }
    }

真正负责打印字符的类：Printer

package com.syz.thread.print;
    
    public class Printer {
    
        private PrinterState who;// 打印谁，由打印状态决定
    
        public void setFirst(PrinterState state) {
            this.who = state;
        }
    
        /**
         * 打印，如果传过来的状态与要打印的状态一样，则打印，并设置要打印的状态为其它线程的状态；否则线程等待。
         * @Title: print
         * @Description: TODO
         * @param c 要打印的字符
         * @param state 当前状态
         * @param status 是否是最后一个要打印的字符，判定某批要打印字符串的结束标志
         * @return: void
         */
        public synchronized void print(char c, PrinterState state, int status) {
            while (who != state) {
                try {
                    this.wait();
                }
                catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            System.out.print(c);
            turn(state);
            if (status != 0) {
                state.setIdle(true);
            }
            this.notifyAll();
        }
    
        private void turn(PrinterState state) {
            PrinterState cur = state;
            if (!cur.getNext().isIdle()) {
                who = cur.getNext();
            }
            else {
                cur = state.getNext();
                turn(cur);
            }
        }
    
    }

打印线程类：PrinterThread

package com.syz.thread.print;
    
    import java.util.LinkedList;
    import java.util.List;
    
    public class PrinterThread extends Thread {
        private String s;
    
        private Printer p;
    
        private PrinterState state;
    
        private static List<PrinterState> spool = new LinkedList<>();
    
        private List<PrinterState> pool = spool;
    
        public PrinterThread(Printer p, String s) {
            if (s == null || "".equals(s)) {
                throw new RuntimeException(getName() + "\t所有打印的字符串不能为空！");
            }
            this.p = p;
            this.s = s;
            PrinterState state = new PrinterState();
            pool.add(state);
            freshPool();
            this.state = pool.get(pool.size() - 1);
            this.p.setFirst(pool.get(0));
        }
    
        /**
         * 重新给打印状态赋值，主要是指定当前状态的下个状态
         * @Title: freshPool
         * @Description: TODO
         * @return: void
         */
        private void freshPool() {
            if (pool.size() > 0) {
                for (int i = 0; i < pool.size(); i++) {
                    PrinterState p1 = pool.get(i);
                    PrinterState p2 = null;
                    if (i == pool.size() - 1) {
                        p2 = pool.get(0);
                    }
                    else {
                        p2 = pool.get(i + 1);
                    }
                    p1.setNext(p2);
                }
            }
        }
    
        public void run() {
            char[] ary = s.toCharArray();
            int len = ary.length;
            for (int i = 0; i < len; i++) {
                try {
                    Thread.sleep(100);
                }
                catch (InterruptedException e) {
                    e.printStackTrace();
                }
                if (i == len - 1) {
                    p.print(ary[i], state, 1);
                }
                else {
                    p.print(ary[i], state, 0);
                }
            }
        }
    }

测试用例1：

String s1 = "1234567890";  
String s2 = "abcdefghij";  
String s3 = "ABCDEFGHIJ";

启三个线程传入s1,s2,s3

结果1：

1aA2bB3cC4dD5eE6fF7gG8hH9iI0jJ

测试用例2：

String s4 = "1357";  
String s5 = "2468";

启两个线程传入s4,s5

结果2：

12345678

测试用例3：

String s1 = "1234567890";  
String s2 = "abc";  
String s3 = "ABCDEFG";