实验存档。
允许好几个人同时读，但是不允许在有人读的时候写，以及同一时间只能有一个人在写。
读者.java：
package operating.entity.readerwriter;
import operating.method.Semaphore;
public class Reader implements Runnable {
private static int total = 0;
private int id;
private Semaphore rmutex, wmutex;
private static int readCount = 0;
public Reader(Semaphore rmutex, Semaphore wmutex) {
id = ++total;
this.rmutex = rmutex;
this.wmutex = wmutex;
}
@Override
public void run() {
while (true) {
rmutex.p();
// 只有第一个读者进程需要执行 wmutex.p()
if (readCount == 0) wmutex.p();
readCount++;
rmutex.v();
// 执行读操作
try {
Thread.sleep(30);
} catch (InterruptedException e) {
e.printStackTrace();
}
rmutex.p();
readCount--;
System.out.println(id + " 号读者结束阅读：当前还剩 " + readCount + " 位读者在读");
if (readCount == 0) wmutex.v();
rmutex.v();
}
}
}写者.java：
package operating.entity.readerwriter;
import operating.method.Semaphore;
public class Writer implements Runnable {
private static int total = 0;
private int id;
private Semaphore wmutex;
public Writer(Semaphore wmutex) {
id = ++total;
this.wmutex = wmutex;
}
@Override
public void run() {
while (true) {
wmutex.p();
// 执行写操作
System.out.println(id + " 号写者正在写");
wmutex.v();
}
}
}主函数.java：
package operating.test; import operating.entity.readerwriter.Reader;
import operating.entity.readerwriter.Writer;
import operating.method.Semaphore; public class ReaderWriterTest {
public static void main(String[] args) {
// 实现写者与写者间、读者与写者间互斥
Semaphore wmutex = new Semaphore(1);
// 用于改变 readCount 变量时实现互斥
Semaphore rmutex = new Semaphore(1); for (int i = 0; i != 5; ++i) {
new Thread(new Writer(wmutex)).start();
new Thread(new Reader(rmutex, wmutex)).start();
}
}
}
/