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。