Android Studio小笔记(4) - Layout

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<!--layout_weight: 每个控件占控比例, 设置它后layout_width影响变小-->
<!-- 线性布局
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/edit_text"
        android:text="消息"
        android:layout_weight="1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"/>

    <Button
        android:id="@+id/button_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

</LinearLayout>
-->

<!--相对布局 RelativeLayout -->
<!--layout_alignParentLeft 靠布局的左边显示 -->
<!--layout_alignParentTop  靠布局的顶部显示 -->
<!--layout_centerInParent  靠布局的中间显示 -->
<!--layout_toRightOf       在某个控件右边显示 -->
<!--layout_above           在某个控件的上面显示 -->
<!--
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/button_1"
        android:text="button1"
        android:layout_above="@+id/button_5"
        android:layout_toRightOf="@+id/button_5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <Button
        android:id="@+id/button_2"
        android:text="button2"
        android:layout_above="@+id/button_5"
        android:layout_toLeftOf="@id/button_5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <Button
        android:id="@+id/button_5"
        android:text="button5"
        android:layout_centerInParent="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

</RelativeLayout>
-->

<!--约束布局 ConstraintLayout -->
<!--layout_alignParentLeft 靠布局的左边显示 -->
<!--layout_constraintBottom_toBottomOf="parent"  本控件的底部位置和parent父控件的底部位置一致,且不能超过 -->
<!--layout_constraintStart_toStartOf="parent"  本控件的底部位置和parent父控件的左边位置一致,且不能超过 -->
<!--layout_constraintHorizontal_bias="0.0"       本控件的水平偏移量,百分比 -->
<!--layout_constraintVertical_bias="0.436"        本控件的垂直便宜量,百分比 -->
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    tools:context=".MainActivity">
    <include layout="@layout/title"/>

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.464"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.486" />

    <TextView
        android:id="@+id/text_view1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="我是textview"
        app:layout_constraintBottom_toTopOf="@+id/button"
        app:layout_constraintEnd_toEndOf="@+id/button"
        app:layout_constraintHorizontal_bias="0.949"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.92" />

</androidx.constraintlayout.widget.ConstraintLayout>

title.xml

<?xml version="1.0" encoding="utf-8"?>
<!--在res\values\themes.xml设置风格: parent="Theme.MaterialComponents.DayNight.DarkActionBar.Bridge-->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:background="@drawable/title_img">

    <Button
        android:id="@+id/back_button"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_margin="5dp"
        android:background="@drawable/back_img"
        android:gravity="center"
        android:text="Back"
        android:textColor="#fff" />
    <TextView
        android:id="@+id/text_view1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:gravity="center"
        android:layout_weight="1"
        android:text="Title text"
        android:textColor="#fff"
        android:textSize="24sp"/>
    <Button
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:gravity="center"
        android:background="@drawable/edit_img"
        android:layout_margin="5dp"
        android:text="Back"
        android:textColor="#fff"
        />

</LinearLayout>

MainActivity.java

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        ActionBar actionBar = getSupportActionBar();
        if(actionBar != null){
            actionBar.hide();   //隐藏原有的标题栏-title
        }
    }
}