UI组件之Button

• 文字大小
• 自定义背景形状
• 自定义按压效果
• 点击事件

练习代码

activity_main.xml

 <Button
        android:id="@+id/btn_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Button"/>

MainActivity.java

public class MainActivity extends AppCompatActivity {

    private Button mBtnButton;

   @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
     mBtnButton = findViewById(R.id.btn_button);
        mBtnButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //跳转到Button演示界面
                Intent intent = new Intent(MainActivity.this,ButtonActivity.class);
                startActivity(intent);
            }
        });
    }
}

activity_button,xml

<?xml version="1.0" encoding="utf-8"?>
<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"
    tools:context=".ButtonActivity"
    android:padding="15dp">

    <Button
        android:id="@+id/btn_1"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:text="按钮1"
        android:textSize ="20sp"
        android:textColor="#FF5722"
        android:background="#FFEB3B"/>

    <Button
        android:id="@+id/btn_2"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:text="按钮2"
        android:textSize="20sp"
        android:textColor="#000000"
        android:background="@drawable/bg_btn2"
        android:layout_below="@+id/btn_1"
        android:layout_marginTop="15dp"/>

    <Button
        android:id="@+id/btn_3"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:text="按钮3"
        android:textSize="20sp"
        android:textColor="#000000"
        android:background="@drawable/bg_btn3"
        android:layout_below="@+id/btn_2"
        android:layout_marginTop="15dp"/>

    <Button
        android:id="@+id/btn_4"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:text="按钮4"
        android:textSize="20sp"
        android:textColor="#000000"
        android:background="@drawable/bg_btn4"
        android:layout_below="@+id/btn_3"
        android:onClick="showToast"
        android:layout_marginTop="15dp"/>

    <TextView
        android:id="@+id/tv_1"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="哈哈哈哈"
        android:gravity="center"
        android:textColor="#9C27B0"
        android:textSize="30sp"
        android:layout_below="@+id/btn_4"
        android:layout_marginTop="15dp"
        android:background="#FFE4E1"/>

</RelativeLayout>

ButtonActivity.java

package com.example.helloworld;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;

public class ButtonActivity extends AppCompatActivity {

    private Button mBtn3;
    private Button mBtn2;
    private TextView mTv1;

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

        mBtn3 = findViewById(R.id.btn_3);
        mBtn3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(ButtonActivity.this,"btn3被点击了",Toast.LENGTH_SHORT).show();
            }
        });

        mBtn2 = findViewById(R.id.btn_2);
        mBtn2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(ButtonActivity.this,"btn2被点击了",Toast.LENGTH_SHORT).show();
            }
        });

        mTv1 = findViewById(R.id.tv_1);
        mTv1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(ButtonActivity.this,"哈哈哈哈被点击了",Toast.LENGTH_SHORT).show();
            }
        });
    }

    public void showToast(View view){
        Toast.makeText(this,"btn4被点击了",Toast.LENGTH_SHORT).show();
    }
}

drawable/bg_btn2.xml：实心圆角

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid
        android:color="#FF9900"/>
    <corners
        android:radius="5dp"/>
</shape>

空心

<stroke
       android:width="1dp"
        android:color="#FF9900"/>

按压效果

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true"> <!--当按钮被按压时实行一些样式-->
        <shape>
            <solid android:color="#99FF33"/>
            <corners android:radius ="5dp" />
        </shape>
    </item>
    <item android:state_pressed="false">
        <shape>
            <solid android:color="#CCFF99"/>
            <corners android:radius ="5dp" />
        </shape>
    </item>
</selector>