自定义TopBar

近期在尝试一款RF手持终端的开发任务，由于系统版本要求，打算采用自定义topbar来作为导航栏，当然v7包里有更好的toolbar可供使用，这里简单做一下示例，仅供参考。
上代码：

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="?attr/actionBarSize"    android:background="@color/colorPrimary"    >    <LinearLayout        android:id="@+id/ll_back"        android:layout_width="40dp"        android:layout_height="?attr/actionBarSize"        android:gravity="center"        >        <ImageView            android:id="@+id/iv_back"            android:layout_width="25dp"            android:layout_height="25dp"            android:src="@drawable/left_back" />    </LinearLayout>    <TextView        android:id="@+id/tv_left"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_toRightOf="@+id/ll_back"        android:layout_centerVertical="true"        android:maxLength="4"        android:textColor="@color/background_light"        android:textSize="16sp" />    <TextView        android:id="@+id/tv_center"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerInParent="true"        android:maxLength="6"        android:textColor="@color/background_light"        android:textSize="16sp"        />    <TextView        android:id="@+id/tv_rightSecond"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerVertical="true"        android:layout_toLeftOf="@+id/tv_rightMost"        android:layout_marginRight="10dp"        android:maxLength="6"        android:textColor="@color/background_light"        android:textSize="16sp"        />    <TextView        android:id="@+id/tv_rightMost"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerVertical="true"        android:maxLength="5"        android:textColor="@color/background_light"        android:layout_marginRight="10dp"        android:layout_alignParentRight="true"        android:textSize="16sp"        /></RelativeLayout>

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public class CustomTitle extends RelativeLayout {    private LayoutInflater inflater;    private View mView;    private TextView tv_left;    private TextView tv_center;    private TextView tv_rightMost;    private TextView tv_rightSecond;    private LinearLayout ll_back;    private ImageView iv_back;    private CustomTitle.CustomToolbarListener listener;    public CustomTitle(Context context) {        super(context);    }    public CustomTitle(Context context, AttributeSet attrs) {        super(context, attrs);        init();        initListener();    }    public CustomTitle(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);    }    private void init() {        if (mView == null) {            inflater = LayoutInflater.from(getContext());            mView = inflater.inflate(R.layout.toolbar_custom, null);            tv_left = (TextView) mView.findViewById(R.id.tv_left);            tv_center = (TextView) mView.findViewById(R.id.tv_center);            tv_rightMost = (TextView) mView.findViewById(R.id.tv_rightMost);            tv_rightSecond = (TextView) mView.findViewById(R.id.tv_rightSecond);            ll_back = (LinearLayout) mView.findViewById(R.id.ll_back);            iv_back = (ImageView) mView.findViewById(R.id.iv_back);            //使用LayoutParams把控件添加到子view中            LayoutParams lp = new LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.WRAP_CONTENT);            addView(mView, lp);        }    }    private void initListener() {        ll_back.setOnClickListener(v -> listener.back(null));    }    public void setBackListener(CustomTitle.CustomToolbarListener backListener) {        this.listener = backListener;    }    public void setTitle(CharSequence title) {        if (tv_center != null) {            if (!TextUtils.isEmpty(title)) {                tv_center.setVisibility(VISIBLE);                tv_center.setText(title);            } else {                tv_center.setVisibility(GONE);            }        }    }    public void setTvLeft(String tvLeft) {        if (!TextUtils.isEmpty(tvLeft)) {            tv_left.setVisibility(VISIBLE);            tv_left.setText(tvLeft);        } else {            tv_left.setVisibility(GONE);        }    }    public void setTvRightMost(String tvRightMost) {        if (!TextUtils.isEmpty(tvRightMost)) {            tv_rightMost.setVisibility(VISIBLE);            tv_rightMost.setText(tvRightMost);        } else {            tv_rightMost.setVisibility(GONE);        }    }    public void setTvRightSecond(String tvRightSecond) {        if (!TextUtils.isEmpty(tvRightSecond)) {            tv_rightSecond.setVisibility(VISIBLE);            tv_rightSecond.setText(tvRightSecond);        } else {            tv_rightSecond.setVisibility(GONE);        }    }    public interface CustomToolbarListener<T> {        void back(T t);    }}