import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.EditText;

import android.widget.ImageView;

import android.widget.Toast;

public class VerifyCodeActivity extends Activity {

 private ImageView vc_image; // 验证码图标

 private String getCode = null; // 获取验证码的值

 private EditText vc_code; // 文本框的值

 @Override

 protected void onCreate(Bundle savedInstanceState) {

  super.onCreate(savedInstanceState);

  setContentView(R.layout.verifycode);

  vc_image = (ImageView) findViewById(R.id.verify_imv);

  vc_code = (EditText) findViewById(R.id.myedit);

  getCode = SecurityCode.getInstance().getCode(false); // 获取显示的验证码

  findViewById(R.id.vc_shuaxin).setOnClickListener(new OnClickListener() {

   @Override

   public void onClick(View v) {

    vc_image.setImageBitmap(SecurityCode.getInstance().getBitmap());

    getCode = SecurityCode.getInstance().getCode(false);

   }

  });

  findViewById(R.id.verfiy).setOnClickListener(new OnClickListener() {

   @Override

   public void onClick(View v) {

    String verfiyString = vc_code.getText().toString();

    if (verfiyString.equals(getCode)) {

     Toast.makeText(getApplicationContext(), "验证码输入正确", Toast.LENGTH_LONG).show();

    } else {

     Toast.makeText(getApplicationContext(), "验证码输入错误", Toast.LENGTH_LONG).show();

    }

   }

  });

 }

}

import java.util.Locale;

import java.util.Random;

import android.graphics.Bitmap;

import android.graphics.Bitmap.Config;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

/**

 * @Description:验证码生成类

 */

public class SecurityCode {

 private static final char[] CHARS = { ‘0‘, ‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘, ‘6‘, ‘7‘, ‘8‘, ‘9‘, ‘a‘, ‘b‘, ‘c‘, ‘d‘, ‘e‘, ‘f‘, ‘g‘, ‘h‘, ‘i‘, ‘j‘, ‘k‘, ‘l‘, ‘m‘, ‘n‘, ‘o‘, ‘p‘, ‘q‘, ‘r‘, ‘s‘, ‘t‘, ‘u‘, ‘v‘, ‘w‘, ‘x‘, ‘y‘, ‘z‘, ‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘, ‘G‘, ‘H‘, ‘I‘, ‘J‘, ‘K‘, ‘L‘, ‘M‘, ‘N‘, ‘O‘, ‘P‘, ‘Q‘, ‘R‘, ‘S‘, ‘T‘, ‘U‘, ‘V‘, ‘W‘, ‘X‘, ‘Y‘, ‘Z‘ };

 private static SecurityCode bpUtil;

 public static SecurityCode getInstance() {

  if (bpUtil == null)

   bpUtil = new SecurityCode();

  return bpUtil;

 }

 // default settings

 private static final int DEFAULT_CODE_LENGTH = 4;// 验证码的长度 这里是4位

 private static final int DEFAULT_FONT_SIZE = 60;// 字体大小

 private static final int DEFAULT_LINE_NUMBER = 3;// 多少条干扰线

 private static final int BASE_PADDING_LEFT = 20; // 左边距

 private static final int RANGE_PADDING_LEFT = 35;// 左边距范围值

 private static final int BASE_PADDING_TOP = 42;// 上边距

 private static final int RANGE_PADDING_TOP = 15;// 上边距范围值

 private static final int DEFAULT_WIDTH = 200;// 默认宽度.图片的总宽

 private static final int DEFAULT_HEIGHT = 70;// 默认高度.图片的总高

 private final int DEFAULT_COLOR = 0xdf;// 默认背景颜色值

 // settings decided by the layout xml

 // canvas width and height

 private int width = DEFAULT_WIDTH;

 private int height = DEFAULT_HEIGHT;

 // random word space and pading_top

 private int base_padding_left = BASE_PADDING_LEFT;

 private int range_padding_left = RANGE_PADDING_LEFT;

 private int base_padding_top = BASE_PADDING_TOP;

 private int range_padding_top = RANGE_PADDING_TOP;

 // number of chars, lines; font size

 private int codeLength = DEFAULT_CODE_LENGTH;

 private int line_number = DEFAULT_LINE_NUMBER;

 private int font_size = DEFAULT_FONT_SIZE;

 // variables

 private String code;// 保存生成的验证码

 private int padding_left, padding_top;

 private Random random = new Random();

 private Bitmap createBitmap() {

  padding_left = 0;

  Bitmap bp = Bitmap.createBitmap(width, height, Config.ARGB_8888);

  Canvas c = new Canvas(bp);

  code = createCode();

  c.drawColor(Color.rgb(DEFAULT_COLOR, DEFAULT_COLOR, DEFAULT_COLOR));

  Paint paint = new Paint();

  paint.setTextSize(font_size);

  for (int i = 0; i < code.length(); i++) {

   randomTextStyle(paint);

   randomPadding();

   c.drawText(code.charAt(i) + "", padding_left, padding_top, paint);

  }

  for (int i = 0; i < line_number; i++) {

   drawLine(c, paint);

  }

  c.save(Canvas.ALL_SAVE_FLAG);// 保存

  c.restore();//

  return bp;

 }

 /**

  * @Description:是否区分大小写

  */

 public String getCode(boolean isMatchCase) {

  if (isMatchCase) {

   if (code != null) {

    code.toLowerCase(Locale.getDefault());

   }

  } else {

   return code;

  }

  return null;

 }

 public Bitmap getBitmap() {

  return createBitmap();

 }

 private String createCode() {

  StringBuilder buffer = new StringBuilder();

  for (int i = 0; i < codeLength; i++) {

   buffer.append(CHARS[random.nextInt(CHARS.length)]);

  }

  return buffer.toString();

 }

 private void drawLine(Canvas canvas, Paint paint) {

  int color = randomColor();

  int startX = random.nextInt(width);

  int startY = random.nextInt(height);

  int stopX = random.nextInt(width);

  int stopY = random.nextInt(height);

  paint.setStrokeWidth(1);

  paint.setColor(color);

  canvas.drawLine(startX, startY, stopX, stopY, paint);

 }

 private int randomColor() {

  return randomColor(1);

 }

 private int randomColor(int rate) {

  int red = random.nextInt(256) / rate;

  int green = random.nextInt(256) / rate;

  int blue = random.nextInt(256) / rate;

  return Color.rgb(red, green, blue);

 }

 private void randomTextStyle(Paint paint) {

  int color = randomColor();

  paint.setColor(color);

  paint.setFakeBoldText(random.nextBoolean()); // true为粗体，false为非粗体

  float skewX = random.nextInt(11) / 10;

  skewX = random.nextBoolean() ? skewX : -skewX;

  paint.setTextSkewX(skewX); // float类型参数，负数表示右斜，整数左斜

  // paint.setUnderlineText(true); //true为下划线，false为非下划线

  // paint.setStrikeThruText(true); //true为删除线，false为非删除线

 }

 private void randomPadding() {

  padding_left += base_padding_left + random.nextInt(range_padding_left);

  padding_top = base_padding_top + random.nextInt(range_padding_top);

 }

}

布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ImageView
        android:id="@+id/verify_imv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <Button
        android:id="@+id/vc_shuaxin"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="获取验证码" />

    <EditText
        android:id="@+id/myedit"
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:hint="请输入验证码" />

    <Button
        android:id="@+id/verfiy"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="验证输入的验证码是否正确" />

</LinearLayout>