话不多说，先上图片：
其中包括了验证码和账号密码验证简单的登陆界面。要想实现这个功能，博主可是花费了一番功夫，今天把经验分享出来，跟大家分享，第一次写博客，后面我也会把我近期Android的一些项目贴出来，供大家踩坑。
CodeUtils
package com.example.myapplication;import android.graphics.Bitmap;import android.graphics.Bitmap.Config;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import java.util.Random;/*** Created by HuGuanzZhong.* 用于图片验证码的工具类*/public class CodeUtils {//定义所显示的数据类型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'};// 绘图准备private static CodeUtils mCodeUtils;private int mPaddingLeft, mPaddingTop;private StringBuilder mBuilder = new StringBuilder();private Random mRandom = new Random();private static final int DEFAULT_CODE_LENGTH = 6;//验证码的长度 这里6位，可以简单点，简单一点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 = 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 CodeUtils getInstance() {if (mCodeUtils == null) {mCodeUtils = new CodeUtils();}return mCodeUtils;}public Bitmap createBitmap() {mPaddingLeft = 0;mPaddingTop = 0;Bitmap bitmap = Bitmap.createBitmap(DEFAULT_WIDTH, DEFAULT_HEIGHT, 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);for (int i = 0; i < code.length(); i++) {randomTextStyle(paint);randomPadding();canvas.drawText(code.charAt(i) + "", mPaddingLeft, mPaddingTop, paint);}for (int i = 0; i < DEFAULT_LINE_NUMBER; i++) {drawLine(canvas, paint);}//这段代码，由于API28版本太高不能使用，所以需要降版本，否则报错canvas.save(Canvas.ALL_SAVE_FLAG);canvas.restore();return bitmap;}public String getCode() {return code;}public String createCode() {mBuilder.delete(0, mBuilder.length()); for (int i = 0; i < DEFAULT_CODE_LENGTH; i++) {mBuilder.append(CHARS[mRandom.nextInt(CHARS.length)]);}return mBuilder.toString();}private void drawLine(Canvas canvas, Paint paint) {int color = randomColor();int startX = mRandom.nextInt(DEFAULT_WIDTH);int startY = mRandom.nextInt(DEFAULT_HEIGHT);int stopX = mRandom.nextInt(DEFAULT_WIDTH);int stopY = mRandom.nextInt(DEFAULT_HEIGHT);paint.setStrokeWidth(1);paint.setColor(color);canvas.drawLine(startX, startY, stopX, stopY, paint);}private int randomColor() {mBuilder.delete(0, mBuilder.length());String haxString;for (int i = 0; i < 3; i++) {haxString = Integer.toHexString(mRandom.nextInt(0xFF));if (haxString.length() == 1) {haxString = "0" + haxString;}mBuilder.append(haxString);}return Color.parseColor("#" + mBuilder.toString());}private void randomTextStyle(Paint paint) {int color = randomColor();paint.setColor(color);paint.setFakeBoldText(mRandom.nextBoolean());float skewX = mRandom.nextInt(11) / 10;skewX = mRandom.nextBoolean() ? skewX : -skewX;paint.setTextSkewX(skewX);}private void randomPadding() {mPaddingLeft += BASE_PADDING_LEFT + mRandom.nextInt(RANGE_PADDING_LEFT);mPaddingTop = BASE_PADDING_TOP + mRandom.nextInt(RANGE_PADDING_TOP);}}
这是一个工具类，可以使用我的或者使用其他人的，网上一抓一大把，工具类的使用会有问题，我在做的时候是安卓8.0，由于API是28.会报类型错误。具体错误地点，已经标注出来了。这里一定要注意降级！降级！降级！
API降级方法：
非gradle:File->Project Structure ->选择你所选择的Modules
gradle：修改SdkVersion ，后面牵扯包的引用，具体详情看其他博主详细讲了，我们hai
附上我的build代码
apply plugin: 'com.android.application'android {compileSdkVersion 25buildToolsVersion '27.0.3'defaultConfig {applicationId ".sunshine"minSdkVersion 16targetSdkVersion 25versionCode 1versionName "1.0"testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"}buildTypes {release {minifyEnabled falseproguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'}}repositories {jcenter()}}dependencies {implementation 'com.android.support.constraint:constraint-layout:1.0.2'compile fileTree(include: ['*.jar'], dir: 'libs')testImplementation 'junit:junit:4.12'androidTestImplementation 'com.android.support.test:runner:1.0.2'androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {exclude group: 'com.android.support', module: 'support-annotations'})compile 'com.android.support:support-v4:25.3.1'compile 'com.android.support:support-v13:25.3.1'compile 'com.android.support:cardview-v7:25.3.1'compile 'com.android.support:appcompat-v7:25.3.1'implementation files('libs/okhttp-3.2.0.jar')implementation files('libs/okio-1.12.0.jar')}
使用生成工具类的代码块：
img_yzm.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {//调用工具类codeUtils = CodeUtils.getInstance();//生成bitmapBitmap bitmap = codeUtils.createBitmap();//设置进imageViewimg_yzm.setImageBitmap(bitmap);String code = codeUtils.getCode().toLowerCase();System.out.println("code------------:" + code);}});
最好把code打印出来，毕竟有时候并不一定能看得清。测试使用。
最后贴出整个项目源码：
MainAcitvity:登陆首页
package com.example.myapplication;import android.content.Intent;import android.graphics.Bitmap;import android.os.Handler;import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.text.TextUtils;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.ImageView;import android.widget.Toast;public class MainActivity extends AppCompatActivity {private ImageView img_yzm;private EditText ed_uname, ed_pwd, ed_yzm;private CodeUtils codeUtils;private Button btn_login, btn_cz;private String codeStr, uname, upwd;private String name, pwd;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initView();initData();}private void initView() {img_yzm = (ImageView) findViewById(R.id.img_yzm);ed_uname = (EditText) findViewById(R.id.ed_uname);ed_pwd = (EditText) findViewById(R.id.ed_pwd);ed_yzm = (EditText) findViewById(R.id.ed_yzm);btn_login = (Button) findViewById(R.id.btn_login);btn_cz = (Button) findViewById(R.id.btn_cz);}private void initData() {//设置验证码，验证码项目需要SDK降级codeUtils = CodeUtils.getInstance();Bitmap bitmap = codeUtils.createBitmap();img_yzm.setImageBitmap(bitmap);img_yzm.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {codeUtils = CodeUtils.getInstance();Bitmap bitmap = codeUtils.createBitmap();img_yzm.setImageBitmap(bitmap);String code = codeUtils.getCode().toLowerCase();System.out.println("code------------:" + code);}});// 设置登录按钮btn_login.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {//将获取的验证码进行小写判断codeStr = ed_yzm.getText().toString().trim().toLowerCase();uname = ed_uname.getText().toString().trim();upwd = ed_pwd.getText().toString().trim();String code = codeUtils.getCode().toLowerCase();//进行验证码判断if (null == codeStr || TextUtils.isEmpty(codeStr)||!code.equalsIgnoreCase(codeStr)) {Toast.makeText(MainActivity.this, "请输入正确验证码", Toast.LENGTH_SHORT).show();}//将验证码变成小写字母System.out.println("code------------:" + code);if (code.equalsIgnoreCase(codeStr)) {if (uname.equals(name) && upwd.equals(pwd)) {Toast.makeText(MainActivity.this, "成功登陆", Toast.LENGTH_SHORT).show();Intent intent = new Intent();intent.putExtra("uname", uname);intent.setClass(MainActivity.this, FirstActivity.class);startActivity(intent);} else {Toast.makeText(MainActivity.this, "请输入正确的账号密码", Toast.LENGTH_SHORT).show();}}}});btn_cz.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {ed_pwd.setText("");ed_uname.setText("");ed_yzm.setText("");}});}}
xml文件
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="/apk/res/android"xmlns:app="/apk/res-auto"xmlns:tools="/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"tools:context=".MainActivity"><EditTextandroid:id="@+id/ed_uname"android:layout_marginTop="50dp"android:layout_marginLeft="15dp"android:layout_marginRight="15dp"android:hint="用户名："android:layout_width="match_parent"android:layout_height="wrap_content" /><EditTextandroid:id="@+id/ed_pwd"android:layout_marginTop="20dp"android:layout_marginLeft="15dp"android:layout_marginRight="15dp"android:hint="密码："android:inputType="textPassword"android:layout_width="match_parent"android:layout_height="wrap_content" /><LinearLayoutandroid:layout_margin="30dp"android:orientation="horizontal"android:layout_width="match_parent"android:layout_height="wrap_content"><EditTextandroid:id="@+id/ed_yzm"android:hint="验证码："android:layout_width="0dp"android:layout_weight="4"android:layout_height="match_parent" /><ImageViewandroid:id="@+id/img_yzm"android:layout_marginLeft="5dp"android:layout_width="0dp"android:layout_weight="1.5"android:layout_height="match_parent" /></LinearLayout><LinearLayoutandroid:layout_margin="30dp"android:orientation="horizontal"android:layout_width="match_parent"android:layout_height="wrap_content"><Buttonandroid:id="@+id/btn_login"android:text="登陆"android:layout_marginLeft="15dp"android:layout_width="0dp"android:layout_weight="1"android:layout_height="match_parent" /><Buttonandroid:id="@+id/btn_cz"android:text="重置"android:layout_marginLeft="15dp"android:layout_width="0dp"android:layout_weight="1"android:layout_height="match_parent" /></LinearLayout></LinearLayout>
附：由于代码涉及到服务器验证登陆，所以会有一定的文件不足，敬请见谅。
