在手游开发过程中, 经常会用到需要异步的情况, 也就是多线程, cocos2d-x本身并没有关于线程的相关代码.但幸好ios 及 android系统都实现了Posix系统调用. 这里就利用posix手动开启线程方面,做一个总结,以备忘
先介绍一些基本的线程api
就像每个进程有一个进程ID一样，每个线程也有一个线程ID，进程ID在整个系统中是唯一的，但线程不同，线程ID只在它所属的进程环境中有效。线程ID用pthread_t数据类型来表示，实现的时候可以用一个结构来代表pthread_t数据类型，所以可以移植的操作系统不能把它作为整数处理。因此必须使用函数来对来对两个线程ID进行比较。
1．名称：pthread_equal
功能：比较两个线程ID
头文件：#include <pthread.h>
函数原形：int pthread_equal(pthread_t tid1,pthread_t tid2);
参数：tid1 进程1id, tid2 进程2id
返回值：若相等返回非0值，否则返回0
2．名称：pthread_self
功能：获取自身线程的id
头文件：#include <pthread.h>
函数原形：pthread_t pthread_self(void);
参数：无
返回值：调用线程的线程id
六．线程的创建
3．名称：pthread_create
功能：创建线程
头文件：#include <pthread.h>
函数原形：int pthread_create(pthread_t *restrict tidp,const pthread _attr_t *restrict attr,void *(*start_rtn)(void),void *restrict arg);
参数：
返回值：若成功返回则返回0，否则返回错误编号
举例:一个下载器的实例
DownLoader.h
//
// DownLoader.h
// MythLeague
//
// Created by raochongtao on 13-6-25.
//
//
/*
* 1.开线程
* 2.下载分配给自己的资源
* 3.监听自己是否下载完
* 4.和管理器交互
*/
#ifndef __MythLeague__DownLoader__
#define __MythLeague__DownLoader__
#include "Global/Constants.h"
typedef enum{
DownloadStatus_Init,
DownloadStatus_Loading,
DownloadStatus_Success,
DownloadStatus_FailedWhen_Init,
DownloadStatus_FailedWhen_GetHandle,
DownloadStatus_FailedWhen_GetInfo,
}Enum_DownloadStatus;
class DownLoader : public cocos2d::CCObject{
public:
DownLoader();
virtual ~DownLoader();
CREATE_FUNC(DownLoader);
bool init();
//下载资源
void downloadRes(Struct_DownLoadTask p_downloadTask);
//开线程
static void* startNewThread(void* args);
bool startDownload();
//处理下载数据
static size_t process_data(void *buffer, size_t size, size_t nmemb, std::string& user_p);
//监测下载完毕
void checkDownloadStatus(float p_delay);
public:
Struct_DownLoadTask m_downloadTask;
Enum_DownloadStatus m_iDownloadStatus;
};
#endif /* defined(__MythLeague__DownLoader__) */
DownLoader.cpp
//
// DownLoader.cpp
// MythLeague
//
// Created by raochongtao on 13-6-25.
//
//
#include "DownLoader.h"
#include "DownloadMgr.h"
#include "Global/Tools.h"
#define FILE_EXIST (200)
#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
#include "CURL/curl.h"
#elif (CC_TARGET_PLATFORM == CC_PLATFORM_WIN32)
#include "platform/third_party/win32/curl/curl.h"
#elif (CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID)
#include "platform/third_party/android/modules/libcurl/include/curl/curl.h"
#endif
using namespace std;
using namespace cocos2d;
#define DownLoader_Check_Interval (0.5f)
DownLoader::DownLoader(){
m_iDownloadStatus = DownloadStatus_Init;
}
DownLoader::~DownLoader(){
}
bool DownLoader::init(){
return true;
}
//下载资源
void DownLoader::downloadRes(Struct_DownLoadTask p_downloadTask){
m_downloadTask = p_downloadTask;
pthread_t l_pid;
pthread_attr_t l_attr;
pthread_attr_init(&l_attr);
int l_iPriority = sched_get_priority_max(SCHED_OTHER);
pthread_attr_setschedpolicy(&l_attr, l_iPriority);
pthread_create(&l_pid, &l_attr, DownLoader::startNewThread, this);
CCDirector::sharedDirector()->getScheduler()->scheduleSelector(schedule_selector(DownLoader::checkDownloadStatus), this, DownLoader_Check_Interval, false);
}
//开线程(静态方法)
void* DownLoader::startNewThread(void* p_args){
//线程独立
pthread_detach(pthread_self());
//自己新线程里下载
DownLoader* l_thisDownloader = (DownLoader*)p_args;
l_thisDownloader->startDownload();
return NULL;
}
bool DownLoader::startDownload(){
m_iDownloadStatus = DownloadStatus_Loading;
#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS || CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID)
// 初始化libcurl
CURLcode return_code;
return_code = curl_global_init(CURL_GLOBAL_ALL);
if (CURLE_OK != return_code)
{
CCLog("init libcurl failed.");
curl_global_cleanup();
m_iDownloadStatus = DownloadStatus_FailedWhen_Init;
return false;
}
// 获取easy handle
CURL *easy_handle = curl_easy_init();
if (NULL == easy_handle)
{
CCLog("get a easy handle failed.");
curl_easy_cleanup(easy_handle);
curl_global_cleanup();
m_iDownloadStatus = DownloadStatus_FailedWhen_GetHandle;
return false;
}
// 设置easy handle属性
return_code = curl_easy_setopt(easy_handle, CURLOPT_URL, m_downloadTask.resUrl.c_str());
//设置回调函数
//return_code = curl_easy_setopt(easy_handle, CURLOPT_WRITEFUNCTION, &process_data);
curl_easy_setopt(easy_handle, CURLOPT_WRITEFUNCTION, process_data);
//回调函数的额外参数
std::string connectx;
return_code = curl_easy_setopt(easy_handle, CURLOPT_WRITEDATA, &connectx);
// 执行数据请求
return_code = curl_easy_perform(easy_handle);
//判断获取响应的http地址是否存在,若存在则返回200,400以上则为不存在,一般不存在为404错误
int retcode = 0;
return_code = curl_easy_getinfo(easy_handle, CURLINFO_RESPONSE_CODE , &retcode);
if (CURLE_OK == return_code && FILE_EXIST == retcode)
{
double length = 0;
return_code = curl_easy_getinfo(easy_handle, CURLINFO_CONTENT_LENGTH_DOWNLOAD , &length);
string l_fullPath = Tools::getWritableFilePath(m_downloadTask.fileName.c_str());
FILE *fp = fopen(l_fullPath.c_str(), "wb+");
if(fp != NULL){
fwrite(connectx.c_str(), 1, length, fp); //返回实际写入文本的长度,若不等于length则写文件发生错误.
fclose(fp);
}else{
CCLog("error here file: %s line: %d", __FILE__, __LINE__);
}
}
else
{
CCLog("......url文件不存在!");
curl_easy_cleanup(easy_handle);
curl_global_cleanup();
m_iDownloadStatus = DownloadStatus_FailedWhen_GetInfo;
return false;
}
// 释放资源
curl_easy_cleanup(easy_handle);
curl_global_cleanup();
#endif
m_iDownloadStatus = DownloadStatus_Success;
return 0;
}
//处理下载数据
size_t DownLoader::process_data(void *buffer, size_t size, size_t nmemb, std::string& user_p){
user_p.append((char*)buffer, size*nmemb);
return size*nmemb;
}
//监测下载完毕
void DownLoader::checkDownloadStatus(float p_delay){
if (m_iDownloadStatus >= DownloadStatus_Success) {
CCDirector::sharedDirector()->getScheduler()->unscheduleSelector(schedule_selector(DownLoader::checkDownloadStatus), this);
//成功回调
if (m_iDownloadStatus == DownloadStatus_Success) {
DownloadMgr::sharedMgr()->callWhenDownloaderFinish_success(this);
}
//失败回调
else{
DownloadMgr::sharedMgr()->callWhenDownloaderFinish_failed(this);
}
}
}
这样实现了，一个下载器的基本功能，但在处理异常方面还有待完善。
其它需要做的还有，需要写一个下载管理器，管理器的基本功能要包括:
/*
* 1.管理下载器,一个或多个
* 2.显示DownLoading及进度
* 并屏蔽事件
* 3.与外部交互的接口
*/
另外，还需要一个用于显示下载内容及下载进度的显示层。
这两个层，会陆续传上来。