Android自定义控件深入学习 Android生成随机验证码

在上一篇的文章中介绍了自定义控件的属性，详情见《详解Android自定义控件属性TypedArray以及attrs》。那么在这基础上实现随机验证码生成，里面的代码是自定义控件以及涉及到自定义view绘画。
1、先看实现的效果图

看到这个效果图是不是感觉还可以。那么就看看源码吧。
2、attr文件

<?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>

3、布局layout

<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="点击验证码，换一张" />
 </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="输入验证码" /> 

  <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="验证" /> 

</LinearLayout>

4、自定义AuthCodeView.class
继承View，重写了

onMeasure(int widthMeasureSpec, int heightMeasureSpec)

onDraw(Canvas canvas)方法。
看代码，有详细注释了。

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
{
 // 点数设置
 public static final int POINT_NUM = 100;
 // 线段数设置
 public static final int LINE_NUM = 2;
 //文本
 private String mTitleText;
 // 文本的颜色
 private int mTitleTextColor;
 // 文本的大小
 private int mTitleTextSize; 

 String[] mCheckNum = new String[4];
 Random random = new Random(); 

 //绘制时控制文本绘制的范围
 private Rect mBound;
 private Paint mPaint; 

 public AuthCodeView(Context context, AttributeSet attrs)
 {
  this(context, attrs, 0);
 } 

 public AuthCodeView(Context context)
 {
  this(context, null);
 } 

 /**
  * 获得我自定义的样式属性
  *
  * @param context
  * @param attrs
  * @param defStyle
  */
 public AuthCodeView(Context context, AttributeSet attrs, int defStyle)
 {
  super(context, attrs, defStyle);
  /**
   * 获得我们所定义的自定义样式属性
   */
  TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.AuthCodeView, defStyle, 0); 

  //获取在attr文件下，名字为AuthCodeView的declare-styleable属性有几个
  int n = a.getIndexCount();
  for (int i = 0; i < n; i++)
  {
   int attr = a.getIndex(i);
   switch (attr)
   {
   //这个属性可以不要，因为都是随机产生
   case R.styleable.AuthCodeView_titleText:
    mTitleText = a.getString(attr);
    break;
   case R.styleable.AuthCodeView_titleTextColor:
    // 默认颜色设置为黑色
    mTitleTextColor = a.getColor(attr, Color.BLACK);
    break;
   case R.styleable.AuthCodeView_titleTextSize:
    // 默认设置为16sp，TypeValue也可以把sp转化为px
    mTitleTextSize = a.getDimensionPixelSize(attr, (int) TypedValue.applyDimension(
      TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics()));
    break; 

   } 

  }
  a.recycle(); 

  mTitleText = randomText(); 

  /**
   * 获得绘制文本的宽和高
   */
  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();
   } 

  }); 

 } 

 //随机产生验证码
 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();
 } 

 //获取验证码
 public String getAuthCode() {
  return mTitleText;
 } 

 //重写这个方法，设置自定义view控件的大小
 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
 {
  // super.onMeasure(widthMeasureSpec, heightMeasureSpec); 

  int width = 0;
  int height = 0; 

  /**
   * 设置宽度
   */
  int specMode = MeasureSpec.getMode(widthMeasureSpec);
  int specSize = MeasureSpec.getSize(widthMeasureSpec);
  switch (specMode)
  {
  case MeasureSpec.EXACTLY:// 明确指定了
   width = getPaddingLeft() + getPaddingRight() + specSize;
   break;
  case MeasureSpec.AT_MOST:// 一般为WARP_CONTENT
   width = getPaddingLeft() + getPaddingRight() + mBound.width();
   break;
  } 

  /**
   * 设置高度
   */
  specMode = MeasureSpec.getMode(heightMeasureSpec);
  specSize = MeasureSpec.getSize(heightMeasureSpec);
  switch (specMode)
  {
  case MeasureSpec.EXACTLY:// 明确指定了
   height = getPaddingTop() + getPaddingBottom() + specSize;
   break;
  case MeasureSpec.AT_MOST:// 一般为WARP_CONTENT
   height = getPaddingTop() + getPaddingBottom() + mBound.height();
   break;
  } 

  setMeasuredDimension(width, height); 

 } 

 @Override
 protected void onDraw(Canvas canvas)
 {
  //画背景颜色
  mPaint.setColor(Color.BLUE);
  canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), mPaint); 

  //划线
  mPaint.setColor(mTitleTextColor);
  int [] line;
  for(int i = 0; i < LINE_NUM; i ++)
  {
   //设置线宽
   mPaint.setStrokeWidth(5);
   line = getLine(getMeasuredHeight(), getMeasuredWidth());
   canvas.drawLine(line[0], line[1], line[2], line[3], mPaint);
  } 

  // 绘制小圆点
  int [] point;
  int randomInt;
  for(int i = 0; i < POINT_NUM; i ++)
  {
   //随机获取点的大小
   randomInt = random.nextInt(5);
   point = getPoint(getMeasuredHeight(), getMeasuredWidth());
   canvas.drawCircle(point[0], point[1], randomInt, mPaint);
  } 

  //绘制验证控件上的文本
  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);
 } 

 //计算验证码的绘制y点位置
 private int getPositon(int height) {
  int tempPositoin = (int) (Math.random() * height);
  if (tempPositoin < 20) {
   tempPositoin += 20;
  }
  return tempPositoin;
 } 

 // 随机产生点的圆心点坐标
 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;
 } 

 //随机产生划线的起始点坐标和结束点坐标
 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中怎么使用这个自定义AuthCodeView
package 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, "验证码验证正确！", Toast.LENGTH_LONG).show();
   }else {
    Toast.makeText(this, "验证码错误！", Toast.LENGTH_LONG).show();
   }
   break; 

  default:
   break;
  } 

 } 

}

源码下载：Android生成随机验证码Demo

以上就是本文的全部内容，希望对大家的学习有所帮助。