消息隊列是一個存放在內核中的消息鏈表，每個消息隊列由隊列標識符標識，與管道不同的是消息隊列是放在內核當中，只有在內核重啟，或者顯式的刪除一個消息隊列，該消息隊列才會被真正的刪除，以下會有幾個操作，

1.創(chuàng)建消息隊列

#include

#include

key_t ftok(const char* pathname,int proj_id);

根據傳入的參數的唯一性，創(chuàng)建一個消息隊列

int? msgget(key_t key,int msgflag);

該參數ley是即為ftok函數的返回值，mshflag是一個標識參數

IPC_CREATE：如果內核中不存在于key相等的消息隊列，則新建一個消息隊列

IPC_EXCL和IPC_CREATE一起使用，如果對應鍵值的消息對流已經存在，則出錯，返回-1

2.寫消息隊列

int msgsnd(int msgid,struct msgbuf* msgp,size_t msgz,int msgflag)

msgid是消息隊列的標識

msgp是發(fā)送的消息

msgz要發(fā)送的消息的大小

msgflag操作標識，當他是0的時候，當消息隊列已曼則，msgsnd則會阻塞，直到可以寫入，如果msgflag是

IPC_NOWAIT的時候，如果消息隊列已滿則，立即返回

3.讀消息隊列

int msgrcv(int msgid,struct msgbuf* msgp,size_t msglen,long msgtyp,int msgflag);

現(xiàn)在源代碼如下

msg_server.c

/*
?*?main.cpp
?*
?*??Created?on:?Jul?18,?2014
?*??????Author:?john
?*/

#include#include#include#include#include#include#include#include#include#include#include#define?BUF_SIZE?256
#define?PROJ_ID??32
#define?PATH_NAME?"/tmp"
#define?SERVER_MSG??1
#define?CLIENT_MSG?2
using?namespace?std;



int?main()
{
???struct?mymsg
???{
?????long?msgtype;
?????char?content[256];
???}msgbuf;
???
??//?var?define
???int?qid;//消息隊列標識
????int?msglen;//消息長度
???key_t?msgkey;
?
??//獲取鍵值
??msgkey=ftok(PATH_NAME,PROJ_ID);
??if(msgkey==-1)
???{
?????cout<<"sorry?key?create?failed:?"<<strerror(errno)<<endl;
?????exit(0);???
??}
??//獲取消息隊列
??cout<<"創(chuàng)建鍵值成功n";
??
??qid=msgget(msgkey,IPC_CREAT|0666);
??if(qid==-1)
???{
??????cout<<"get?msg?quen?failed?"<<strerror(errno)<<endl;
??????exit(0);
???}
??cout<<"獲取消息隊列成功"<<qid<<"n";
??//開始讀取和寫入消息
??while(1)
??{
?????cout<>msgbuf.content;
?????if(strncmp(msgbuf.content,"exit",4)==0)
?????{
????	?//獲取消息屬性，IPC——RMID從內核中刪除qid的消息隊列
?????????msgctl(qid,IPC_RMID,NULL);
?????????exit(0);
?????}
?????msgbuf.msgtype=SERVER_MSG;
??????if(?msgsnd(qid,&msgbuf,strlen(msgbuf.content)+1,0)==-1)
?????{
??????????cout<<"msg?send?failed"<<endl;
??????????exit(1);
?????}
??????cout<<"正在接收客戶端的消息n";
?????if(msgrcv(qid,&msgbuf,BUF_SIZE,CLIENT_MSG,0)==-1)
?????{
?????????cout<<"msg?rcv?failed"<<endl;
?????????exit(0);
?????}
?????cout<<"Client:?"<<msgbuf.content<<endl;
?????
??}
}

msg_client.c文件如下：

/*
?*?main.cpp
?*
?*??Created?on:?Jul?18,?2014
?*??????Author:?john
?*/

#include#include#include#include#include#include#include#include#include#include#include#define?BUF_SIZE?256
#define?PROJ_ID??32
#define?PATH_NAME?"/tmp"
#define?SERVER_MSG??1
#define?CLIENT_MSG?2
using?namespace?std;



int?main()
{
???struct?mymsg
???{
?????long?msgtype;
?????char?content[256];
???}msgbuf;

??//?var?define
???int?qid;//消息隊列標識
????int?msglen;//消息長度
???key_t?msgkey;

??//獲取鍵值
??msgkey=ftok(PATH_NAME,PROJ_ID);
??if(msgkey==-1)
???{
?????cout<<"sorry?key?create?failed:?"<<strerror(errno)<<endl;
?????exit(0);
??}
??cout<<"獲取鍵值成功n";
??//獲取消息隊列

??qid=msgget(msgkey,IPC_CREAT|0666);
??if(qid==-1)
???{
??????cout<<"get?msg?quen?failed?"<<strerror(errno)<<endl;
??????exit(0);
???}
??cout<<"獲取消息隊列成功"<<qid<<"n";
??//開始讀取和寫入消息
??while(1)
??{
	??cout<<"正在接收服務器給客戶段的消息n";
	??if(msgrcv(qid,&msgbuf,BUF_SIZE,SERVER_MSG,0)==-1)
	??????{
	??????????cout<<"msg?rcv?failed"<<endl;
	??????????exit(0);
	??????}
	??????cout<<"Server:?"<<msgbuf.content<<endl;
?????cout<>msgbuf.content;
?????if(strncmp(msgbuf.content,"exit",4)==0)
?????{
????	?//獲取消息屬性，IPC——RMID從內核中刪除qid的消息隊列
?????????msgctl(qid,IPC_RMID,NULL);
?????????exit(0);
?????}
?????msgbuf.msgtype=CLIENT_MSG;
??????if(?msgsnd(qid,&msgbuf,strlen(msgbuf.content)+1,0)==-1)
?????{
??????????cout<<"msg?send?failed"<<endl;
??????????exit(1);
?????}
??}
}

唯一需要注意的是，在msgrcv的參數中要寫入需要接收的消息的類型。