>what</em>,
* <em>arg1</em>, <em>arg2</em>, and <em>obj</em> members.
。。。。
* @param obj The <em>obj</em> value to set.
* @return A Message object from the global pool.
*/
public static Message obtain(Handler h, int what,
int arg1, int arg2, Object obj) {
Message m = obtain();
m.target = h;
m.what = what;
m.arg1 = arg1;
m.arg2 = arg2;
m.obj = obj;
return m;
}
还有几个没列举出来，都是先调用obtain()方法，然后把获取的Message实例加上各种参数。代码一目了然。。。
recycle():回收当前message到全局池
/**
* Return a Message instance to the global pool.
* <p>
* You MUST NOT touch the Message after calling this function because it has
* effectively been freed. It is an error to recycle a message that is currently
* enqueued or that is in the process of being delivered to a Handler.
* </p>
*/
public void recycle() {
if (isInUse()) {
if (gCheckRecycle) {
throw new IllegalStateException("This message cannot be recycled because it "
+ "is still in use.");
}
return;
}
recycleUnchecked();
}
/**
* Recycles a Message that may be in-use.
* Used internally by the MessageQueue and Looper when disposing of queued Messages.
*/
void recycleUnchecked() {
// Mark the message as in use while it remains in the recycled object pool.
// Clear out all other details.
flags = FLAG_IN_USE;
what = 0;
arg1 = 0;
arg2 = 0;
obj = null;
replyTo = null;
sendingUid = -1;
when = 0;
target = null;
callback = null;
data = null;
synchronized (sPoolSync) {
if (sPoolSize < MAX_POOL_SIZE) {
next = sPool;
sPool = this;
sPoolSize++;
}
}
}
向全局池中返回一个Message实例。一定不能在调用此函数后再使用Message——它实际上已经被释放。
getWhen：
/**
* Return the targeted delivery time of this message, in milliseconds.
*/
public long getWhen() {
return when;
}
返回此消息的传输时间，以毫秒为单位。
setTarget，getTarget：
//设置handler和返回handler
public void setTarget(Handler target) {
this.target = target;
}
/**
* Retrieve the a {@link android.os.Handler Handler} implementation that
* will receive this message. The object must implement
* {@link android.os.Handler#handleMessage(android.os.Message)
* Handler.handleMessage()}. Each Handler has its own name-space for
* message codes, so you do not need to
* worry about yours conflicting with other handlers.
*/
public Handler getTarget() {
return target;
}
获取将接收此消息的Handler对象。此对象必须要实现Handler.handleMessage()方法。每个handler各自包含自己的消息代码，所以不用担心自定义的消息跟其他handlers有冲突。
setData：
设置一个可以是任何类型值的bundle。
/**
* Sets a Bundle of arbitrary data values. Use arg1 and arg2 members
* as a lower cost way to send a few simple integer values, if you can.
* @see #getData()
* @see #peekData()
*/
public void setData(Bundle data) {
this.data = data;
}
getData，peekData
public Bundle getData() {
if (data == null) {
data = new Bundle();
}
return data;
}
public Bundle peekData() {
return data;
}
发送消息的一些方法：
/**向Handler发送此消息，getTarget()方法可以获取此Handler。如果这个字段没有设置会抛出个空指针异常。
* Sends this Message to the Handler specified by {@link #getTarget}.
* Throws a null pointer exception if this field has not been set.
*/
public void sendToTarget() {
target.sendMessage(this);
}
构造方法：
/** Constructor (but the preferred way to get a Message is to call {@link #obtain() Message.obtain()}).
*/
public Message() {
}
//推荐使用Message.o