Android高手进阶教程(四)之----Android 中自定义属性(a.doc

今天我们的教程是根据前面一节扩展进行的，如果你没有看,请点击 Android高手进阶教程(三) 查看第三课,这样跟容易方便你的理解!在xml 文件里定义控件的属性，我们已经习惯了android:attrs= ,那么我们能不能定义自己的属性能，比如:test:attrs= 呢？答案是肯定的.好了我就不卖关子了，直接进入主题。大致以下步骤:一、 在res/values 文件下定义一个attrs.xml 文件.代码如下:view plaincopy to clipboardprint?一、在res/values文件下定义一个attrs.xml文件.代码如下: 1 2 3 4 5 6 7 8 一、在res/values文件下定义一个attrs.xml文件.代码如下: 9 10 11 12 13 14 15 二、 我们在MyView.java 代码修改如下，其中下面的构造方法是重点，我们获取定义的属性我们R.sytleable.MyView_textColor, 获取方法中后面通常设定默认值(float textSize = a.getDimension(R.styleable.MyView_textSize, 36 ); )， 防止我们在xml 文件中没有定义.从而使用默认值!获取，MyView 就是定义在 里的名字,获取里面属性用 名字_ 属性 连接起来就可以.TypedArray 通常最后调用 .recycle() 方法，为了保持以后使用该属性一致性！view plaincopy to clipboardprint? 16 public MyView(Context context,AttributeSet attrs) 17 18 super(context,attrs); 19 mPaint = new Paint(); 20 21 TypedArray a = context.obtainStyledAttributes(attrs, 22 R.styleable.MyView); 23 24 int textColor = a.getColor(R.styleable.MyView_textColor, 25 0XFFFFFFFF); 26 float textSize = a.getDimension(R.styleable.MyView_textSize, 36); 27 28 mPaint.setTextSize(textSize); 29 mPaint.setColor(textColor); 30 31 a.recycle(); 32 33 public MyView(Context context,AttributeSet attrs) 34 35 super(context,attrs); 36 mPaint = new Paint(); 37 38 TypedArray a = context.obtainStyledAttributes(attrs, 39 R.styleable.MyView); 40 41 int textColor = a.getColor(R.styleable.MyView_textColor, 42 0XFFFFFFFF); 43 float textSize = a.getDimension(R.styleable.MyView_textSize, 36); 44 45 mPaint.setTextSize(textSize); 46 mPaint.setColor(textColor); 47 48 a.recycle(); 49 MyView.java 全部代码如下:view plaincopy to clipboardprint? 50 package com.android.tutor; 51 import android.content.Context; 52 import android.content.res.TypedArray; 53 import android.graphics.Canvas; 54 import android.graphics.Color; 55 import android.graphics.Paint; 56 import android.graphics.Rect; 57 import android.graphics.Paint.Style; 58 import android.util.AttributeSet; 59 import android.view.View; 60 public class MyView extends View 61 private Paint mPaint; 62 private Context mContext; 63 private static final String mString = Welcome to Mr Weis blog; 64 65 public MyView(Context context) 66 super(context); 67 mPaint = new Paint(); 68 69 public MyView(Context context,AttributeSet attrs) 70 71 super(context,attrs); 72 mPaint = new Paint(); 73 74 TypedArray a = context.obtainStyledAttributes(attrs, 75 R.styleable.MyView); 76 77 int textColor = a.getColor(R.styleable.MyView_textColor, 78 0XFFFFFFFF); 79 float textSize = a.getDimension(R.styleable.MyView_textSize, 36); 80 81 mPaint.setTextSize(textSize); 82 mPaint.setColor(textColor); 83 84 a.recycle(); 85 86 Override 87 protected void onDraw(Canvas canvas) 88 / TODO Auto-generated method stub 89 super.onDraw(canvas); 90 /设置填充 91 mPaint.setStyle(Style.FILL); 92 93 /画一个矩形,前俩个是矩形左上角坐标，后面俩个是右下角坐标 94 canvas.drawRect(new Rect(10, 10, 100, 100), mPaint); 95 96 mPaint.setColor(Color.BLUE); 97 /绘制文字 98 canvas.drawText(mString, 10, 110, mPaint); 99 100 101 package com.android.tutor; 102 import android.content.Context; 103 import android.content.res.TypedArray; 104 import android.graphics.Canvas; 105 import android.graphics.Color; 106 import android.graphics.Paint; 107 import android.graphics.Rect; 108 import android.graphics.Paint.Style; 109 import android.util.AttributeSet; 110 import android.view.View; 111 public class MyView extends View 112 private Paint mPaint; 113 private Context mContext; 114 private static final String mString = Welcome to Mr Weis blog; 115 116 public MyView(Context context) 117 super(context); 118 mPaint = new Paint(); 119 120 public MyView(Context context,AttributeSet attrs) 121 122 super(context,attrs); 123 mPaint = new Paint(); 124 125 TypedArray a = context.obtainStyledAttributes(attrs, 126 R.styleable.MyView); 127 128 int textColor = a.getColor(R.styleable.MyView_textColor, 129 0XFFFFFFFF); 130 float textSize = a.getDimension(R.styleable.MyView_textSize, 36); 131 132 mPaint.setTextSize(textSize); 133 mPaint.setColor(textColor); 134 135 a.recycle(); 136 137 Override 138 protected void onDraw(Canvas canvas) 139 / TODO Auto-generated method stub 140 super.onDraw(canvas); 141 /设置填充 142 mPaint.setStyle(Style.FILL); 143 144 /画一个矩形,前俩个是矩形左上角坐标，后面俩个是右下角坐标 145 canvas.drawRect(new Rect(10, 10, 100, 100), mPaint); 146 147 mPaint.setColor(Color.BLUE); 148 /绘制文字 149 canvas.drawText(mString, 10, 110, mPaint); 150 151 三、将我们