<?xml version="1.0" encoding="utf-8"?> <resources>   <attr name="titleText" format="string" />  <attr name="titleTextColor" format="color" />  <attr name="titleTextSize" format="dimension" />   <declare-styleable name="AuthCodeView">   <attr name="titleText" />   <attr name="titleTextColor" />   <attr name="titleTextSize" />  </declare-styleable>  </resources> 

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:tools="http://schemas.android.com/tools"  xmlns:authcodeview="http://schemas.android.com/apk/res/com.example.authcodeview"  android:id="@+id/LinearLayout1"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:orientation="vertical" >   <LinearLayout   android:layout_width="match_parent"   android:layout_height="wrap_content" >    <com.example.authcodeview.view.AuthCodeView    android:id="@+id/AuthCodeView"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:padding="10dp"    authcodeview:titleText="3712"    authcodeview:titleTextColor="#00ffff"    authcodeview:titleTextSize="40sp" />    <TextView    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="點擊驗證碼，換一張" />  </LinearLayout>   <LinearLayout   android:layout_width="match_parent"   android:layout_height="wrap_content" >    <TextView    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="輸入驗證碼" />    <EditText    android:id="@+id/editText1"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:ems="10"    android:inputType="number" >     <requestFocus />   </EditText>  </LinearLayout>   <Button   android:id="@+id/button1"   android:layout_width="match_parent"   android:layout_height="wrap_content"   android:text="驗證" />  </LinearLayout> 

onMeasure(int widthMeasureSpec, int heightMeasureSpec)

package com.example.authcodeview.view;  import java.util.Random;  import com.example.authcodeview.R;  import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Rect; import android.util.AttributeSet; import android.util.TypedValue; import android.view.View;  public class AuthCodeView extends View {  // 點數設置  public static final int POINT_NUM = 100;  // 線段數設置  public static final int LINE_NUM = 2;  //文本  private String mTitleText;  // 文本的顏色  private int mTitleTextColor;  // 文本的大小  private int mTitleTextSize;    String[] mCheckNum = new String[4];  Random random = new Random();    //繪制時控制文本繪制的范圍  private Rect mBound;  private Paint mPaint;   public AuthCodeView(Context context, AttributeSet attrs)  {   this(context, attrs, 0);  }   public AuthCodeView(Context context)  {   this(context, null);  }   /**   * 獲得我自定義的樣式屬性   *   * @param context   * @param attrs   * @param defStyle   */  public AuthCodeView(Context context, AttributeSet attrs, int defStyle)  {   super(context, attrs, defStyle);   /**    * 獲得我們所定義的自定義樣式屬性    */   TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.AuthCodeView, defStyle, 0);      //獲取在attr文件下，名字為AuthCodeView的declare-styleable屬性有幾個   int n = a.getIndexCount();   for (int i = 0; i < n; i++)   {    int attr = a.getIndex(i);    switch (attr)    {    //這個屬性可以不要，因為都是隨機產生    case R.styleable.AuthCodeView_titleText:     mTitleText = a.getString(attr);     break;    case R.styleable.AuthCodeView_titleTextColor:     // 默認顏色設置為黑色     mTitleTextColor = a.getColor(attr, Color.BLACK);     break;    case R.styleable.AuthCodeView_titleTextSize:     // 默認設置為16sp，TypeValue也可以把sp轉化為px     mTitleTextSize = a.getDimensionPixelSize(attr, (int) TypedValue.applyDimension(       TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics()));     break;     }    }   a.recycle();      mTitleText = randomText();    /**    * 獲得繪制文本的寬和高    */   mPaint = new Paint();   mPaint.setTextSize(mTitleTextSize);   mBound = new Rect();   mPaint.getTextBounds(mTitleText, 0, mTitleText.length(), mBound);    this.setOnClickListener(new OnClickListener()   {     @Override    public void onClick(View v)    {     mTitleText = randomText();     postInvalidate();    }    });   }    //隨機產生驗證碼  private String randomText()  {   StringBuffer sbReturn = new StringBuffer();   for (int i = 0; i < 4; i++) {    StringBuffer sb = new StringBuffer();    int randomInt = random.nextInt(10);    mCheckNum[i] = sb.append(randomInt).toString();    sbReturn.append(randomInt);   }      return sbReturn.toString();  }    //獲取驗證碼  public String getAuthCode() {   return mTitleText;  }   //重寫這個方法，設置自定義view控件的大小  @Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)  {   // super.onMeasure(widthMeasureSpec, heightMeasureSpec);    int width = 0;   int height = 0;    /**    * 設置寬度    */   int specMode = MeasureSpec.getMode(widthMeasureSpec);   int specSize = MeasureSpec.getSize(widthMeasureSpec);   switch (specMode)   {   case MeasureSpec.EXACTLY:// 明確指定了    width = getPaddingLeft() + getPaddingRight() + specSize;    break;   case MeasureSpec.AT_MOST:// 一般為WARP_CONTENT    width = getPaddingLeft() + getPaddingRight() + mBound.width();    break;   }    /**    * 設置高度    */   specMode = MeasureSpec.getMode(heightMeasureSpec);   specSize = MeasureSpec.getSize(heightMeasureSpec);   switch (specMode)   {   case MeasureSpec.EXACTLY:// 明確指定了    height = getPaddingTop() + getPaddingBottom() + specSize;    break;   case MeasureSpec.AT_MOST:// 一般為WARP_CONTENT    height = getPaddingTop() + getPaddingBottom() + mBound.height();    break;   }    setMeasuredDimension(width, height);   }   @Override  protected void onDraw(Canvas canvas)  {   //畫背景顏色   mPaint.setColor(Color.BLUE);   canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), mPaint);      //劃線   mPaint.setColor(mTitleTextColor);   int [] line;   for(int i = 0; i < LINE_NUM; i ++)   {    //設置線寬    mPaint.setStrokeWidth(5);    line = getLine(getMeasuredHeight(), getMeasuredWidth());    canvas.drawLine(line[0], line[1], line[2], line[3], mPaint);   }      // 繪制小圓點   int [] point;   int randomInt;   for(int i = 0; i < POINT_NUM; i ++)    {    //隨機獲取點的大小    randomInt = random.nextInt(5);    point = getPoint(getMeasuredHeight(), getMeasuredWidth());    canvas.drawCircle(point[0], point[1], randomInt, mPaint);   }    //繪制驗證控件上的文本   int dx = 20;   for(int i = 0; i < 4; i ++){    canvas.drawText("" + mCheckNum[i],dx, getHeight() / 2 + getPositon(mBound.height() / 2), mPaint);    dx += (getWidth() / 2 - mBound.width() / 2) + i / 5 + 20;   } //  canvas.drawText(mTitleText, getWidth() / 2 - mBound.width() / 2, getHeight() / 2 + mBound.height() / 2, mPaint);  }    //計算驗證碼的繪制y點位置  private int getPositon(int height) {   int tempPositoin = (int) (Math.random() * height);   if (tempPositoin < 20) {    tempPositoin += 20;   }   return tempPositoin;  }    // 隨機產生點的圓心點坐標  public static int[] getPoint(int height, int width) {   int[] tempCheckNum = { 0, 0, 0, 0 };   tempCheckNum[0] = (int) (Math.random() * width);   tempCheckNum[1] = (int) (Math.random() * height);   return tempCheckNum;  }    //隨機產生劃線的起始點坐標和結束點坐標  public static int[] getLine(int height, int width) {   int[] tempCheckNum = { 0, 0, 0, 0 };   for (int i = 0; i < 4; i += 2) {    tempCheckNum[i] = (int) (Math.random() * width);    tempCheckNum[i + 1] = (int) (Math.random() * height);   }   return tempCheckNum;  } } 5、在MainActivity中怎么使用這個自定義AuthCodeViewpackage com.example.authcodeview;  import com.example.authcodeview.view.AuthCodeView; import android.os.Bundle; import android.app.Activity; import android.view.View; import android.view.View.OnClickListener; import android.widget.EditText; import android.widget.Toast;  public class MainActivity extends Activity implements OnClickListener {   private AuthCodeView mauthCodeView;  @Override  protected void onCreate(Bundle savedInstanceState)  {   super.onCreate(savedInstanceState);   setContentView(R.layout.activity_main);      initUI();  }   private void initUI() {   mauthCodeView = (AuthCodeView)findViewById(R.id.AuthCodeView);   findViewById(R.id.button1).setOnClickListener(this);  }   @Override  public void onClick(View v) {   switch (v.getId()) {   case R.id.button1:    EditText editText = (EditText)findViewById(R.id.editText1);    String codeString = editText.getText().toString().trim();    if (codeString.equals(mauthCodeView.getAuthCode())) {     Toast.makeText(this, "驗證碼驗證正確！", Toast.LENGTH_LONG).show();    }else {     Toast.makeText(this, "驗證碼錯誤！", Toast.LENGTH_LONG).show();    }    break;    default:    break;   }     }   }