android tv开发基础知识焦点处理

机顶盒开发和手机开发最大的区别就在于view的事件处理上了,机顶盒开发没什么touch事件,而机顶盒是用遥控器去操作界面交互的,而手机是用手去操作界面的,所以我们用遥控器去操作界面表示你焦点在哪个view上,一般都在该view上把背景设置为和其他的view有区别或者是放大的效果,这样体验起来效果就更好,现在写个demo体验下,

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"     >    <LinearLayout        android:layout_width="600dp"        android:layout_height="match_parent"        android:orientation="vertical">        <Button             android:id="@+id/button1"            android:layout_width="400dp"            android:layout_height="wrap_content"            android:text="button1"            />        <Button             android:id="@+id/button2"            android:layout_width="400dp"            android:layout_height="wrap_content"            android:text="button2"            />        <Button             android:id="@+id/button3"            android:layout_width="400dp"            android:layout_height="wrap_content"            android:text="button3"            />        <Button             android:id="@+id/button4"            android:layout_width="400dp"            android:layout_height="wrap_content"            android:text="button4"            />        <Button             android:id="@+id/button5"            android:layout_width="400dp"            android:layout_height="wrap_content"            android:text="button5"            /></LinearLayout><LinearLayout        android:layout_width="600dp"        android:layout_height="match_parent"        android:orientation="vertical"        android:layout_marginLeft="40dp"        >        <Button             android:id="@+id/button6"            android:layout_width="400dp"            android:layout_height="wrap_content"            android:text="button6"            />        <Button             android:id="@+id/button7"            android:layout_width="400dp"            android:layout_height="wrap_content"            android:text="button7"            />        <Button             android:id="@+id/button8"            android:layout_width="400dp"            android:layout_height="wrap_content"            android:text="button8"            />        <Button             android:id="@+id/button9"            android:layout_width="400dp"            android:layout_height="wrap_content"            android:text="button9"            />        <Button             android:id="@+id/button10"            android:layout_width="400dp"            android:layout_height="wrap_content"            android:text="button10"            /></LinearLayout></LinearLayout>

这上面是10个button,现在看下使用遥控器操作的效果,

哪个button有焦点,但是系统给它设置的背景色很浅,所以我们一般都是自己去设置当哪个view有焦点的时候,view有setOnClickListener点击事件,当然也给我们设置了获取焦点的回调,setOnFocusChangeListener就是当view有焦点时候回调,
public void onFocusChange(View v, boolean hasFocus) {

}

v表示你当前哪个view有焦点,

hasFocus返回true表示v获取到焦点,返回false表示该view没有焦点,所以当view有焦点设置其背景一般就在这个方法,这个在机顶盒开发很普遍的做法,

@Overridepublic void onFocusChange(View v, boolean hasFocus) {if(hasFocus){setViewNormalBg();switch (v.getId()) {case R.id.button1:setViewFouceBg(button1);break;case R.id.button2:setViewFouceBg(button2);break;case R.id.button3:setViewFouceBg(button3);break;case R.id.button4:setViewFouceBg(button4);break;case R.id.button5:setViewFouceBg(button5);break;case R.id.button6:setViewFouceBg(button6);break;case R.id.button7:setViewFouceBg(button7);break;case R.id.button8:setViewFouceBg(button8);break;case R.id.button9:setViewFouceBg(button9);break;case R.id.button10:setViewFouceBg(button10);break;}}}public void setViewFouceBg(View view){view.setBackgroundColor(Color.RED);}public void setViewNormalBg(){button1.setBackgroundColor(Color.TRANSPARENT);button2.setBackgroundColor(Color.TRANSPARENT);button3.setBackgroundColor(Color.TRANSPARENT);button4.setBackgroundColor(Color.TRANSPARENT);button5.setBackgroundColor(Color.TRANSPARENT);button6.setBackgroundColor(Color.TRANSPARENT);button7.setBackgroundColor(Color.TRANSPARENT);button8.setBackgroundColor(Color.TRANSPARENT);button9.setBackgroundColor(Color.TRANSPARENT);button10.setBackgroundColor(Color.TRANSPARENT);}

当button有焦点时背景设置为红色,其他没有焦点的view背景色就是透明的,这样用户一看就知道点击到哪个view了,

还有就是遥控器有左,右,上,下四个键,这个就要涉及到view的setOnKeyListener监听了,遥控器有down和up事件,对应的就是KeyEvent.KEYCODE_DPAD_DOWN,KeyEvent.KEYCODE_DPAD_UP,KeyEvent.KEYCODE_DPAD_LEFT,KeyEvent.KEYCODE_DPAD_RIGHT，

button1.setOnKeyListener(new OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if(event.getAction()==KeyEvent.ACTION_DOWN){
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_LEFT:
Log.e(TAG,"左----------");
break;
case KeyEvent.KEYCODE_DPAD_RIGHT:
Log.e(TAG,"右----------");
break;
case KeyEvent.KEYCODE_DPAD_UP:
Log.e(TAG,"上----------");
break;
case KeyEvent.KEYCODE_DPAD_DOWN:
Log.e(TAG,"下----------");
break;
}
}
return false;
}
});

这个onKey()方法有一个boolean的返回值,上面的如果你上,下,左,右返回true的话就表示屏蔽了系统默认的处理方式,而右你自己去处理,一旦你返回true,界面上那么view就没有焦点了,可以调用isFocused()这个方法 打印它的返回值就知道它返回false，就表示view没有焦点了,如果这个时候要让view有焦点就必须调用requestFocus让它获取到焦点

button1.setOnKeyListener(new OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if(event.getAction()==KeyEvent.ACTION_DOWN){
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_UP:
return true;
case KeyEvent.KEYCODE_DPAD_DOWN:
button2.requestFocus();
return true;
}
}
return false;
}
});
button2.setOnKeyListener(new OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if(event.getAction()==KeyEvent.ACTION_DOWN){
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_UP:
button1.requestFocus();
return true;
case KeyEvent.KEYCODE_DPAD_DOWN:
button3.requestFocus();
return true;
}
}
return false;
}
});
button3.setOnKeyListener(new OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if(event.getAction()==KeyEvent.ACTION_DOWN){
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_UP:
button2.requestFocus();
return true;
case KeyEvent.KEYCODE_DPAD_DOWN:
button4.requestFocus();
return true;
}
}
return false;
}
});
button4.setOnKeyListener(new OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if(event.getAction()==KeyEvent.ACTION_DOWN){
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_UP:
button3.requestFocus();
return true;
case KeyEvent.KEYCODE_DPAD_DOWN:
button5.requestFocus();
return true;
}
}
return false;
}
});
button5.setOnKeyListener(new OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if(event.getAction()==KeyEvent.ACTION_DOWN){
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_UP:
button4.requestFocus();
return true;
case KeyEvent.KEYCODE_DPAD_DOWN:
return true;
}
}
return false;
}
});

这个是屏蔽了系统的处理方式,自己处理的效果,