redis C接口函數

原創

2020-02-21 09:58

hiredis是redis數據庫的C接口，目前只能在linux下使用，幾個基本的函數就可以操作redis數據庫了。

函數原型：redisContext *redisConnect(const char *ip, int port)
說明：該函數用來連接redis數據庫，參數爲數據庫的ip地址和端口，一般redis數據庫的端口爲6379
該函數返回一個結構體redisContext。

函數原型：void *redisCommand(redisContext *c, const char *format, …);
說明：該函數執行命令，就如sql數據庫中的SQL語句一樣，只是執行的是redis數據庫中的操作命令，第一個參數爲連接數據庫時返回的redisContext，剩下的參數爲變參，就如C標準函數printf函數一樣的變參。返回值爲void*，一般強制轉換成爲redisReply類型的進行進一步的處理。

函數原型void freeReplyObject(void *reply);
說明：釋放redisCommand執行後返回的redisReply所佔用的內存

函數原型：void redisFree(redisContext *c);
說明：釋放redisConnect()所產生的連接。

下面用一個簡單的例子說明：

#include <stdio.h>  
#include <stdlib.h>  
#include <stddef.h>  
#include <stdarg.h>  
#include <string.h>  
#include <assert.h>  
#include <hiredis/hiredis.h>  

void doTest()  
{  
    //redis默認監聽端口爲6387 可以再配置文件中修改  
    redisContext* c = redisConnect("127.0.0.1", 6379);  
    if ( c->err)  
    {  
        redisFree(c);  
        printf("Connect to redisServer faile\n");  
        return ;  
    }  
    printf("Connect to redisServer Success\n");  

    const char* command1 = "set stest1 value1";  
    redisReply* r = (redisReply*)redisCommand(c, command1);  

    if( NULL == r)  
    {  
        printf("Execut command1 failure\n");  
        redisFree(c);  
        return;  
    }  
    if( !(r->type == REDIS_REPLY_STATUS && strcasecmp(r->str,"OK")==0))  
    {  
        printf("Failed to execute command[%s]\n",command1);  
        freeReplyObject(r);  
        redisFree(c);  
        return;  
    }     
    freeReplyObject(r);  
    printf("Succeed to execute command[%s]\n", command1);  

    const char* command2 = "strlen stest1";  
    r = (redisReply*)redisCommand(c, command2);  
    if ( r->type != REDIS_REPLY_INTEGER)  
    {  
        printf("Failed to execute command[%s]\n",command2);  
        freeReplyObject(r);  
        redisFree(c);  
        return;  
    }  
    int length =  r->integer;  
    freeReplyObject(r);  
    printf("The length of 'stest1' is %d.\n", length);  
    printf("Succeed to execute command[%s]\n", command2);  


    const char* command3 = "get stest1";  
    r = (redisReply*)redisCommand(c, command3);  
    if ( r->type != REDIS_REPLY_STRING)  
    {  
        printf("Failed to execute command[%s]\n",command3);  
        freeReplyObject(r);  
        redisFree(c);  
        return;  
    }  
    printf("The value of 'stest1' is %s\n", r->str);  
    freeReplyObject(r);  
    printf("Succeed to execute command[%s]\n", command3);  

    const char* command4 = "get stest2";  
    r = (redisReply*)redisCommand(c, command4);  
    if ( r->type != REDIS_REPLY_NIL)  
    {  
        printf("Failed to execute command[%s]\n",command4);  
        freeReplyObject(r);  
        redisFree(c);  
        return;  
    }  
    freeReplyObject(r);  
    printf("Succeed to execute command[%s]\n", command4);     


    redisFree(c);  

}  

int main()  
{  
    doTest();  
    return 0;  
}