原理很简单，首先封装一个类，里面是绘制的图形验证码的一些信息，比如，验证码字符串，验证码长度，干扰线等等，这个网上有很多，我也是参考某个的的封装类写的，下面先上效果图：
代码如下：
package com.imageverification;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import java.util.Random;
/**
* Created by Administrator on 2018/5/14/014.
*/
public class CodeUtil {
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',
};
private static CodeUtil mCodeUtil;
private int paddingLeft,paddingTop;
private StringBuilder stringBuilder=new StringBuilder();
private Random random=new Random();
private static final int DEFAULT_CODE_LENGTH=4;//验证码长度
private static final int DEFAULT_FONT_SIZE =60;//验证码字体大小
private static final int DEFAULT_LINE_NUMBER =3;//干扰线
private static final int BASE_PADDING_LEFT = 40; //左边距
private static final int RANGE_PADDING_LEFT = 30;//左边距范围值
private static final int BASE_PADDING_TOP = 70;//上边距
private static final int RANGE_PADDING_TOP = 15;//上边距范围值
private static final int DEFAULT_WIDTH = 300;//默认宽度.图片的总宽
private static final int DEFAULT_HEIGHT = 100;//默认高度.图片的总高
private static final int DEFAULT_COLOR = 0xDF;//默认背景颜色值
private String code;
public static CodeUtil getInstence(){
if (mCodeUtil == null){
mCodeUtil=new CodeUtil();
}
return mCodeUtil;
}
//生成bitmap形式的验证码图片可通过image.setBitmap();获取展示图片
public Bitmap createBitmap(){
paddingLeft=0;
paddingTop=0;
Bitmap bitmap= Bitmap.createBitmap(DEFAULT_WIDTH,DEFAULT_HEIGHT,Bitmap.Config.ARGB_8888);
Canvas canvas=new Canvas(bitmap);
code=createCode();
canvas.drawColor(Color.rgb(DEFAULT_COLOR,DEFAULT_COLOR,DEFAULT_COLOR));
Paint paint=new Paint();
paint.setTextSize(DEFAULT_FONT_SIZE);
//验证码
for (int i = 0; i <code.length() ; i++) {
randomTextStyle(paint);
randomPadding();
canvas.drawText(String.valueOf(code.charAt(i)),paddingLeft,paddingTop,paint);
}
//干扰线
for (int j = 0; j <DEFAULT_LINE_NUMBER ; j++) {
drawLine(canvas,paint);
}
canvas.save();
canvas.restore();
return bitmap;
}
/**
* 得到图片验证码字符串信息
*/
public String getCode(){
return code;
}
//生成干扰线
private void drawLine(Canvas canvas, Paint paint) {
int color =randomColor();
int startX = random.nextInt(DEFAULT_WIDTH);
int startY = random.nextInt(DEFAULT_HEIGHT);
int stopX = random.nextInt(DEFAULT_WIDTH);
int stopY = random.nextInt(DEFAULT_HEIGHT);
paint.setStrokeWidth(1);
paint.setColor(color);
canvas.drawLine(startX, startY, stopX, stopY, paint);
}
//随机颜色
private int randomColor() {
stringBuilder.delete(0, stringBuilder.length()); //使用之前首先清空内容
String haxString;
for (int i = 0; i < 3; i++) {
haxString = Integer.toHexString(random.nextInt(0xFF));
if (haxString.length() == 1) {
haxString = "0" + haxString;
}
stringBuilder.append(haxString);
}
return Color.parseColor("#" + stringBuilder.toString());
}
//随机间距
private void randomPadding() {
paddingLeft += BASE_PADDING_LEFT + random.nextInt(RANGE_PADDING_LEFT);
paddingTop = BASE_PADDING_TOP + random.nextInt(RANGE_PADDING_TOP);
}
//随机文本样式
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
}
//生成验证码
private String createCode() {
stringBuilder.delete(0,stringBuilder.length());
for (int i = 0; i <DEFAULT_CODE_LENGTH ; i++) {
stringBuilder.append(CHARS[random.nextInt(CHARS
.length)]);
}
return stringBuilder.toString();
}
}
activity侧：
package com.imageverification;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
/**
* 图形验证码小demo
*/
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private EditText editText;
private ImageView imageView;
private Button button;
private String finalCode;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
}
private void initView() {
editText=findViewById(R.id.ed);
imageView=findViewById(R.id.img);
button=findViewById(R.id.btn);
imageView.setImageBitmap(CodeUtil.getInstence().createBitmap());
finalCode=CodeUtil.getInstence().getCode();
button.setOnClickListener(this);
imageView.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()){
case R.id.btn:
String message=editText.getText().toString();
if (message.equalsIgnoreCase(finalCode)){
Toast.makeText(MainActivity.this,"验证码输入成功",Toast.LENGTH_SHORT).show();
}else {
Toast.makeText(MainActivity.this,"验证码输入失败",Toast.LENGTH_SHORT).show();
}
break;
case R.id.img:
imageView.setImageBitmap(CodeUtil.getInstence().createBitmap());
finalCode=CodeUtil.getInstence().getCode();
break;
}
}
}
布局没有什么东西就不贴了。
注：在此说明刚刚说明，（给我自己看的）：由于自己疏忽把代码改了一种写法，为了减少代码量，我直接在类的上面去实现了点击事件，刚开始是两个都设置了setOnClickListener事件，然后只给button设置了上下文，imageView忘记了，在点击的时候随机码切换不了。
完整代码：https://download.csdn.net/download/qq_36636969/10414614