首先我们在res/values目录下建一个xml文件夹，一般取名为attrs。
<?xml version="1.0" encoding="utf-8"?> <resources> <!--name 自定义View的名字 TextView--> <declare-styleable name="MyTextView"> <!-- name 属性名称 format 格式: string 文字 color 颜色 dimension 宽高 字体大小 integer 数字 reference 资源（drawable） --> <attr name="lzyText" format="string"/> <attr name="lzyTextColor" format="color"/> <attr name="lzyTextSize" format="dimension"/> <attr name="lzyMaxLength" format="integer"/> <!-- 枚举 --> <attr name="lzyInputType"> <enum name="number" value="1"/> <enum name="text" value="2"/> <enum name="password" value="3"/> </attr> </declare-styleable> </resources>自己的布局文件里面使用：
<?xml version="1.0" encoding="utf-8"?> <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="vertical" tools:context="com.example.michael.view_01.MainActivity"> <com.example.michael.view_01.MyTextView android:layout_width="wrap_content" android:layout_height="wrap_content" app:lzyText="hello world" app:lzyTextColor="@color/colorAccent" app:lzyTextSize="20sp" /> </LinearLayout>注意：
xmlns:app="http://schemas.android.com/apk/res-auto"一定要有这样的命名空间！
自定义TextView：
public class MyTextView extends View { private String mText; private int mTextColor; private int mTextSize; private Paint mPaint; //构造函数在代码new的时候调用 public MyTextView(Context context) { this(context,null); } //在布局中使用 public MyTextView(Context context, @Nullable AttributeSet attrs) { this(context, attrs,0); } //在不居中调用，布局中有style的情况 public MyTextView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); TypedArray a = context.obtainStyledAttributes(attrs,R.styleable.MyTextView); mText = a.getString(R.styleable.MyTextView_lzyText); mTextColor = a.getColor(R.styleable.MyTextView_lzyTextColor, Color.BLACK); mTextSize = a.getDimensionPixelSize(R.styleable.MyTextView_lzyTextSize,20); a.recycle(); mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setTextSize(mTextSize); mPaint.setColor(mTextColor); } //布局的宽高都是有这个方法指定 @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { //super.onMeasure(widthMeasureSpec, heightMeasureSpec); //获取宽高的模式 int widthMode = MeasureSpec.getMode(widthMeasureSpec); int heightMode = MeasureSpec.getMode(heightMeasureSpec); int width = MeasureSpec.getSize(widthMeasureSpec); if (widthMode == MeasureSpec.AT_MOST){ Rect rect = new Rect(); mPaint.getTextBounds(mText,0,mText.length(),rect); width = rect.width(); } int height = MeasureSpec.getSize(heightMeasureSpec); if (heightMode == MeasureSpec.AT_MOST){ Rect r = new Rect(); mPaint.getTextBounds(mText,0,mText.length(),r); height = r.height(); } setMeasuredDimension(width,height); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); Paint.FontMetricsInt fontMetricsInt = mPaint.getFontMetricsInt(); int dy = 0; dy = (fontMetricsInt.bottom - fontMetricsInt.top)/2 - fontMetricsInt.bottom; int baseLine = getHeight()/2 + dy; canvas.drawText(mText,0,baseLine,mPaint); } }
