以下代碼爲改良版。
public class ProducerConsumer {
static final int N = 3; // constant giving the buffer size
static producer p = new producer(); // instantiate a new producer thread
static consumer c = new consumer( ); // instantiate a new consumer thread
static our_monitor mon = new our_monitor( ); // instantiate a new monitor
public static void main(String args[]) {
p.start(); // start the producer thread
c.start(); // start the consumer thread
}
static class producer extends Thread {
public void run( ) {// run method contains the thread code
int item;
while (true) { //producer loop
item = produce_item( );
mon.insert(item);
}
}
private int produce_item( ) { // actually produce
return 0;
}
}
static class consumer extends Thread {
public void run( ) {//run method contains the thread code
int item;
while (true) { // consumer loop
item = mon.remove( );
consume_item (item);
}
}
private void consume_item(int item) {
}// actually consume
}
static class our_monitor {// this is a monitor
private int buffer[] = new int[N];
private int count = 0, lo = 0, hi = 0; // counters and indices
public synchronized void insert(int val){
if (count >= N) {
go_to_sleep(count,hi,"Insert"); // if the buffer is full, go to sleep
}
buffer[hi] = val; // insert an item into the buffer
System.out.println("Produce number:" + val + ",at position=" + hi+ "\r\n");
hi = (hi + 1) % N; // slot to place next item in
count = count + 1; // one more item in the buffer now
notify(); // if consumer was sleeping, wake it up
}
public synchronized int remove( ) {
int val;
if (count == 0) {
go_to_sleep(count,lo,"Remove"); // if the buffer is empty, go to sleep
}
val = buffer [lo]; // fetch an item from the buffer
System.out.println("Consume number:" + val+ ",at position=" + lo + "\r\n");
lo = (lo + 1) % N; // slot to fetch next item from
count = count - 1; // one few items in the buffer
notify( ); // if producer was sleeping, wake it up
return val;
}
private void go_to_sleep(int count,int val,String action) {
try{
System.out.println("Current total number:" + count+ ",value=" + val+",Action=" + action+ "\r\n");
wait( );
} catch(InterruptedException exc){
}
}
}
}
//Figure 2-35. A solution to the producer-consumer problem in Java,copy from <<Modern Operating System>> by Andrew S.Tanenbaum.先前從書中摘抄的，似乎不能正確執行。
public class ProducerConsumer {
static final int N = 3; // constant giving the buffer size
static producer p = new producer(); // instantiate a new producer thread
static consumer c = new consumer( ); // instantiate a new consumer thread
static our_monitor mon = new our_monitor( ); // instantiate a new monitor
public static void main(String args[]) {
p.start(); // start the producer thread
c.start(); // start the consumer thread
}
static class producer extends Thread {
public void run( ) {// run method contains the thread code
int item;
while (true) { //producer loop
item = produce_item( );
mon.insert(item);
}
}
private int produce_item( ) { // actually produce
return 0;
}
}
static class consumer extends Thread {
public void run( ) {//run method contains the thread code
int item;
while (true) { // consumer loop
item = mon.remove( );
consume_item (item);
}
}
private void consume_item(int item) {
}// actually consume
}
static class our_monitor {// this is a monitor
private int buffer[] = new int[N];
private int count = 0, lo = 0, hi = 0; // counters and indices
public synchronized void insert(int val){
if (count == N) go_to_sleep(); // if the buffer is full, go to sleep
buffer[hi] = val; // insert an item into the buffer
System.out.println("Produce number:" + val + ",at position=" + hi);
hi = (hi + 1) % N; // slot to place next item in
count = count + 1; // one more item in the buffer now
if (count == 1) notify(); // if consumer was sleeping, wake it up
}
public synchronized int remove( ) {
int val;
if (count == 0) go_to_sleep(); // if the buffer is empty, go to sleep
val = buffer [lo]; // fetch an item from the buffer
System.out.println("Consume number:" + val+ ",at position=" + lo);
lo = (lo + 1) % N; // slot to fetch next item from
count = count - 1; // one few items in the buffer
if (count == N - 1) notify( ); // if producer was sleeping, wake it up
return val;
}
private void go_to_sleep( ) {
try{
System.out.println("隊列不能滿足要求，掛起。。。\\n");
wait( );
} catch(InterruptedException exc){
}
}
}
}
//Figure 2-35. A solution to the producer-consumer problem in Java.