android 自定義view組件

 

原創作品，允許轉載，轉載時請務必以超鏈接形式標明文章 原始出處 、作者信息和本聲明。否則將追究法律責任。http://weizhulin.blog.51cto.com/1556324/311457

大家好我們今天的教程是在Android 教程中自定義View 的學習，對於初學着來說，他們習慣了Android 傳統的頁面佈局方式，如下代碼:

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello"
    />
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello"
    />
</LinearLayout>

當然上面的佈局方式可以幫助我們完成簡單應用的開發了，但是如果你想寫一個複雜的應用，這樣就有點牽強了，大家不信可以下源碼都研究看看，高手寫的佈局方式，如上面的佈局高手通常是這樣寫的:

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<?xml version="1.0" encoding="utf-8"?>
<A>
    <B></B>
</A>
<?xml version="1.0" encoding="utf-8"?>
<A>
 <B></B>
</A>

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其中A extends LinerLayout, B extends TextView. 
其中A extends LinerLayout, B extends TextView.

爲了幫助大家更容易理解，我寫了一個簡單的Demo ,具體步驟如下：

首先新建一個Android 工程 命名爲ViewDemo .

然後自定義一個View 類，命名爲MyView(extends View) .代碼如下:

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package com.android.tutor;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Paint.Style;
import android.util.AttributeSet;
import android.view.View;
public class MyView extends View {
    private Paint mPaint;
    private Context mContext;
    private static final String mString = "Welcome to Mr Wei's blog";

    public MyView(Context context) {
        super(context);

    }
    public MyView(Context context,AttributeSet attr)
    {
        super(context,attr);

    }
    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        super.onDraw(canvas);

        mPaint = new Paint();

        //設置畫筆顏色
        mPaint.setColor(Color.RED);
        //設置填充
        mPaint.setStyle(Style.FILL);

        //畫一個矩形,前倆個是矩形左上角座標，後面倆個是右下角座標
        canvas.drawRect(new Rect(10, 10, 100, 100), mPaint);

        mPaint.setColor(Color.BLUE);
        //繪製文字
        canvas.drawText(mString, 10, 110, mPaint);
    }
}
package com.android.tutor;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Paint.Style;
import android.util.AttributeSet;
import android.view.View;
public class MyView extends View {
 private Paint mPaint;
 private Context mContext;
 private static final String mString = "Welcome to Mr Wei's blog";

 public MyView(Context context) {
  super(context);

 }
 public MyView(Context context,AttributeSet attr)
 {
  super(context,attr);

 }
 @Override
 protected void onDraw(Canvas canvas) {
  // TODO Auto-generated method stub
  super.onDraw(canvas);

  mPaint = new Paint();

  //設置畫筆顏色
  mPaint.setColor(Color.RED);
  //設置填充
  mPaint.setStyle(Style.FILL);

  //畫一個矩形,前倆個是矩形左上角座標，後面倆個是右下角座標
  canvas.drawRect(new Rect(10, 10, 100, 100), mPaint);

  mPaint.setColor(Color.BLUE);
  //繪製文字
  canvas.drawText(mString, 10, 110, mPaint);
 }
}

然後將我們自定義的View 加入到main.xml 佈局文件中,代碼如下:
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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello"
    />
<com.android.tutor.MyView
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
/>
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello"
    />
<com.android.tutor.MyView
 android:layout_width="fill_parent"
    android:layout_height="fill_parent"
/>
</LinearLayout>