Android 12(S) ALooper AHandler AMessage（二）
作者：互联网
talk is cheap，show me the code！
来写个demo试试看到底是ALooper AHandler AMessage是怎么运行的，源文件以及Android.bp如下：
// EvenHandler.h
#ifndef __MESSAGE_TEST_H__
#define __MESSAGE_TEST_H__
#include <media/stagefright/foundation/AMessage.h>
#include <media/stagefright/foundation/AHandler.h>
#include <media/stagefright/foundation/ALooper.h>
#include <media/stagefright/foundation/ADebug.h>
namespace android{
class EventHandler : public AHandler
{
public:
EventHandler();
enum {
kWhatSetDataSource,
kWhatPrepare,
kWhatStart,
kWhatStop
};
void setDataSource(const char* url);
void prepare();
void start();
void stop();
protected:
virtual void onMessageReceived(const sp<AMessage> &msg);
private:
void onSetDataSource(const char* url);
void onPrepare();
void onStart();
void onStop();
};
}
#endif
// EventHandler.cpp
#define LOG_TAG "MyEventHandler"
#include "EventHandler.h"
#include <string.h>
namespace android{
EventHandler::EventHandler()
{
ALOGD("tid = %d, func = %s", gettid(), __func__);
}
void EventHandler::onMessageReceived(const sp<AMessage> &msg)
{
ALOGD("(%d)oMessageReceived: %s", gettid() ,msg->debugString().c_str());
switch(msg->what()){
case kWhatSetDataSource:
{
AString url;
CHECK(msg->findString("url", &url));
onSetDataSource(url.c_str());
break;
}
case kWhatPrepare:
{
sp<AReplyToken> replyID;
CHECK(msg->senderAwaitsResponse(&replyID));
onPrepare();
sp<AMessage> response = new AMessage;
response->setInt32("err", 0);
response->postReply(replyID);
break;
}
case kWhatStart:
{
onStart();
break;
}
case kWhatStop:
{
onStop();
break;
}
default:
break;
}
}
void EventHandler::setDataSource(const char* url)
{
ALOGD("tid = %d, func = %s", gettid(), __func__);
sp<AMessage> msg = new AMessage(kWhatSetDataSource, this);
msg->setString("url", url, strlen(url));
msg->post();
}
void EventHandler::prepare()
{
ALOGD("tid = %d, func = %s", gettid(), __func__);
sp<AMessage> msg = new AMessage(kWhatPrepare, this);
sp<AMessage> response;
msg->postAndAwaitResponse(&response);
int err;
CHECK(response->findInt32("err", &err));
ALOGD("tid = %d, func = %s, err = %d", gettid(), __func__, err);
}
void EventHandler::start()
{
ALOGD("tid = %d, func = %s", gettid(), __func__);
sp<AMessage> msg = new AMessage(kWhatStart, this);
msg->post();
}
void EventHandler::stop()
{
ALOGD("tid = %d, func = %s", gettid(), __func__);
sp<AMessage> msg = new AMessage(kWhatStop, this);
msg->post();
}
void EventHandler::onSetDataSource(const char *url)
{
ALOGD("tid = %d, func = %s, url = %s", gettid(), __func__, url);
}
void EventHandler::onPrepare()
{
ALOGD("tid = %d, func = %s", gettid(), __func__);
int cnt = 0;
while(cnt < 3)
{
ALOGD("tid = %d, func = %s, cnt = %d", gettid(), __func__, cnt);
sleep(1);
cnt++;
}
}
void EventHandler::onStart()
{
ALOGD("tid = %d, func = %s", gettid(), __func__);
int cnt = 0;
while(cnt < 10)
{
ALOGD("tid = %d, func = %s, cnt = %d", gettid(), __func__, cnt);
sleep(1);
cnt++;
}
}
void EventHandler::onStop()
{
ALOGD("tid = %d, func = %s", gettid(), __func__);
}
}
// main.cpp
#define LOG_TAG "MyEventHandlerTest"
#include "EventHandler.h"
using namespace android;
int main(int argc, char **argv)
{
ALOGD("tid = %d, func = %s", gettid(), __func__);
sp<EventHandler> handler = new EventHandler;
sp<ALooper> looper = new ALooper;
looper->setName("MyLooper");
looper->start();
looper->registerHandler(handler);
handler->setDataSource("ABC");
handler->prepare();
handler->start();
handler->stop();
int wait = 0;
while(wait < 20)
{
ALOGD("wait = %d", wait);
sleep(1);
wait++;
}
}
// Android.bp
cc_binary {
name: "EventHandlerTest",
srcs: [
"EventHandler.cpp",
"main.cpp"
],
shared_libs: [
"libstagefright_foundation",
"libutils",
"liblog"
],
include_dirs: [
"frameworks/av/media/libstagefright/foundation/include"
],
cflags: [
"-Wno-unused-parameter"
]
}
来看执行结果吧，试验了两种情况：
1、先说失败的，将looper->start(true)，这个时候好像直接卡住不动了，
2、直接调用looper->start()，这里的参数默认为false，也就是会在一个新的线程当中做消息处理。从log中来看onMessageReceived方法都是在子线程中完成，在非阻塞的情况下是和主线程并行执行的。
这边还有个现象，main函数最后没有加while循环等待时，子线程执行完onStart方法进程就结束了，并没有等待处理完stop消息
03-25 17:08:23.437 16962 16962 D MyEventHandlerTest: tid = 16962, func = main
03-25 17:08:23.437 16962 16962 D MyEventHandler: tid = 16962, func = EventHandler
03-25 17:08:23.437 16962 16962 D MyEventHandler: tid = 16962, func = setDataSource
03-25 17:08:23.438 16962 16962 D MyEventHandler: tid = 16962, func = prepare
03-25 17:08:23.438 16962 16963 D MyEventHandler: (16963)oMessageReceived: AMessage(what = 0x00000000, target = 1) = {
03-25 17:08:23.438 16962 16963 D MyEventHandler: string url = "ABC"
03-25 17:08:23.438 16962 16963 D MyEventHandler: }
03-25 17:08:23.438 16962 16963 D MyEventHandler: tid = 16963, func = onSetDataSource, url = ABC
03-25 17:08:23.438 16962 16963 D MyEventHandler: (16963)oMessageReceived: AMessage(what = 0x00000001, target = 1) = {
03-25 17:08:23.438 16962 16963 D MyEventHandler: RefBase *replyID = 0xf5b01180
03-25 17:08:23.438 16962 16963 D MyEventHandler: }
03-25 17:08:23.438 16962 16963 D MyEventHandler: tid = 16963, func = onPrepare
03-25 17:08:23.438 16962 16963 D MyEventHandler: tid = 16963, func = onPrepare, cnt = 0
03-25 17:08:24.438 16962 16963 D MyEventHandler: tid = 16963, func = onPrepare, cnt = 1
03-25 17:08:25.438 16962 16963 D MyEventHandler: tid = 16963, func = onPrepare, cnt = 2
03-25 17:08:26.438 16962 16962 D MyEventHandler: tid = 16962, func = prepare, err = 0
03-25 17:08:26.439 16962 16962 D MyEventHandler: tid = 16962, func = start
03-25 17:08:26.439 16962 16962 D MyEventHandler: tid = 16962, func = stop
03-25 17:08:26.439 16962 16962 D MyEventHandlerTest: wait = 0
03-25 17:08:26.439 16962 16963 D MyEventHandler: (16963)oMessageReceived: AMessage(what = 0x00000002, target = 1) = {
03-25 17:08:26.439 16962 16963 D MyEventHandler: }
03-25 17:08:26.439 16962 16963 D MyEventHandler: tid = 16963, func = onStart
03-25 17:08:26.439 16962 16963 D MyEventHandler: tid = 16963, func = onStart, cnt = 0
03-25 17:08:27.439 16962 16962 D MyEventHandlerTest: wait = 1
03-25 17:08:27.439 16962 16963 D MyEventHandler: tid = 16963, func = onStart, cnt = 1
03-25 17:08:28.439 16962 16962 D MyEventHandlerTest: wait = 2
03-25 17:08:28.439 16962 16963 D MyEventHandler: tid = 16963, func = onStart, cnt = 2
03-25 17:08:29.439 16962 16963 D MyEventHandler: tid = 16963, func = onStart, cnt = 3
03-25 17:08:29.439 16962 16962 D MyEventHandlerTest: wait = 3
03-25 17:08:30.439 16962 16963 D MyEventHandler: tid = 16963, func = onStart, cnt = 4
03-25 17:08:30.439 16962 16962 D MyEventHandlerTest: wait = 4
03-25 17:08:31.439 16962 16963 D MyEventHandler: tid = 16963, func = onStart, cnt = 5
03-25 17:08:31.440 16962 16962 D MyEventHandlerTest: wait = 5
03-25 17:08:32.439 16962 16963 D MyEventHandler: tid = 16963, func = onStart, cnt = 6
03-25 17:08:32.440 16962 16962 D MyEventHandlerTest: wait = 6
03-25 17:08:33.440 16962 16963 D MyEventHandler: tid = 16963, func = onStart, cnt = 7
03-25 17:08:33.440 16962 16962 D MyEventHandlerTest: wait = 7
03-25 17:08:34.440 16962 16963 D MyEventHandler: tid = 16963, func = onStart, cnt = 8
03-25 17:08:34.440 16962 16962 D MyEventHandlerTest: wait = 8
03-25 17:08:35.440 16962 16963 D MyEventHandler: tid = 16963, func = onStart, cnt = 9
03-25 17:08:35.440 16962 16962 D MyEventHandlerTest: wait = 9
03-25 17:08:36.440 16962 16963 D MyEventHandler: (16963)oMessageReceived: AMessage(what = 0x00000003, target = 1) = {
03-25 17:08:36.440 16962 16963 D MyEventHandler: }
03-25 17:08:36.440 16962 16963 D MyEventHandler: tid = 16963, func = onStop
03-25 17:08:36.441 16962 16962 D MyEventHandlerTest: wait = 10
03-25 17:08:37.441 16962 16962 D MyEventHandlerTest: wait = 11
03-25 17:08:38.441 16962 16962 D MyEventHandlerTest: wait = 12
03-25 17:08:39.441 16962 16962 D MyEventHandlerTest: wait = 13
03-25 17:08:40.441 16962 16962 D MyEventHandlerTest: wait = 14
03-25 17:08:41.441 16962 16962 D MyEventHandlerTest: wait = 15
03-25 17:08:42.441 16962 16962 D MyEventHandlerTest: wait = 16
03-25 17:08:43.442 16962 16962 D MyEventHandlerTest: wait = 17
03-25 17:08:44.442 16962 16962 D MyEventHandlerTest: wait = 18
03-25 17:08:45.442 16962 16962 D MyEventHandlerTest: wait = 19
标签：25,12,17,03,08,16962,func,ALooper,Android 来源： https://www.cnblogs.com/rongmiao/p/16055798.html