android基礎組件----Button的使用

　　按鈕由文本或圖標（或文本和一個圖標）組成，當用戶觸摸到它時，會發生一些動作。今天我們開始Button的學習。少年的愛情永遠不夠用，一杯酒足以了卻一件心事。

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Button的簡要說明

根據你是否想要一個帶有文本的按鈕，一個圖標，或者兩者，你可以在三種方式中創建按鈕來進行布局：

　　

• With text, using the Button class:

<Buttonandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:text="@string/button_text"... />

• With an icon, using the ImageButton class:

<ImageButtonandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:src="@drawable/button_icon"... />

• With text and an icon, using the Button class with the android:drawableLeft attribute:

<Buttonandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:text="@string/button_text"android:drawableLeft="@drawable/button_icon"... />

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按鈕的響應

1) 在xml中定義的Button中增加屬性android:onClick

• 在xml中定義android:onClick屬性：

<?xml version="1.0" encoding="utf-8"?>
<Button xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="@string/button_send"android:onClick="sendMessage" />

• 在MainActivity中定義sendMessage方法：

public void sendMessage(View view) {// Do something in response to button click
}

2) 在代碼中使用OnClickListener

Button button = (Button) findViewById(R.id.button_send);
button.setOnClickListener(new View.OnClickListener() {public void onClick(View v) {// Do something in response to button click
    }
});

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按鈕樣式

1) Borderless button : To create a borderless button, apply the borderlessButtonStyle style to the button.

<Buttonandroid:onClick="sendMessage"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="bordless button"style="?android:attr/borderlessButtonStyle" />

2) Custom background: Instead of supplying a simple bitmap or color, however, your background should be a state list resource that changes appearance depending on the button's current state

• Create three bitmaps for the button background that represent the default, pressed, and focused button states.?
• Place the bitmaps into the res/drawable/ directory of your project. Be sure each bitmap is named properly to reflect the button state that they each represent.

　　

• Create a new XML file in the res/drawable/ directory (name it something like button_custom.xml). Insert the following XML

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"><item android:drawable="@drawable/button_pressed"android:state_pressed="true" /><item android:drawable="@drawable/button_focused"android:state_focused="true" /><item android:drawable="@drawable/button_default" />
</selector>

• Then simply apply the drawable XML file as the button background

<Buttonandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:text="send button"android:background="@drawable/button_custom"  />

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測試的項目

?項目結構：

MainActivity.java:

package com.huhx.linux.buttontest;import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;public class MainActivity extends AppCompatActivity {private Button button;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);button = (Button) findViewById(R.id.sendButton);button.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {Toast.makeText(MainActivity.this, "button click", Toast.LENGTH_SHORT).show();}});}// bordless buttonpublic void sendMessage(View view) {Toast.makeText(MainActivity.this, "Borderless Button", Toast.LENGTH_SHORT).show();}
}

?button_custom.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"><item android:drawable="@drawable/button_pressed"android:state_pressed="true" /><item android:drawable="@drawable/button_focused"android:state_focused="true" /><item android:drawable="@drawable/button_default" />
</selector>

?activity_main.xml.xml

<?xml version="1.0" encoding="utf-8"?>
<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"android:orientation="vertical"tools:context="com.huhx.linux.buttontest.MainActivity"><Buttonandroid:id="@+id/sendButton"android:text="text button"android:layout_width="wrap_content"android:layout_height="wrap_content" /><ImageButtonandroid:src="@mipmap/ic_launcher"android:layout_width="wrap_content"android:layout_height="wrap_content" /><Buttonandroid:drawableRight="@mipmap/ic_launcher"android:text="Linux"android:layout_width="wrap_content"android:layout_height="wrap_content" /><Buttonandroid:onClick="sendMessage"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="bordless button"style="?android:attr/borderlessButtonStyle" /><Buttonandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:text="send button"android:background="@drawable/button_custom"  />
</LinearLayout>

?運行效果如下：

友情鏈接

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