Android之登录那点事

　　随着互联网的高速发展，一个应用为了保护用户的隐私，通常会通过设置用户名+密码的验证方式保证用户隐私的相对安全，我知道一般网站的登录验证，通常会设置一个二维码，通过验证二维码，防止恶意软件通过机械程序，对用户密码进行破解，那么Android设备如何实现这个功能呢？相信很多开发者对此不屑一顾，因为这样增加了用户使用的复杂性，很多软件是不会这样设计的，现在我们暂且不谈它是不是有用，今天我们重点探讨一下，如何在Android的设备上实现这个功能。本篇为大家介绍的内容包括：1、用户连续多次输错密码，增加验证码验证；2、Android如何通过http请求达到与服务器之间的通讯。好了下面开始我们今天内容的介绍，首先我们先一起来学习一下如何实现用户连续多次输错密码，增加验证码功能。

　　既然用的到二维码，那么Android如何生成二维码呢？为大家提供一个生成二维码的类：

//生成二维码的类
public class BPUtil {

    /**
     * 用于生成二维码的字符
     */
    private static final char[] CHARS = {
        '', '', '', '', '', '', '', '', '', '',
        'a','b','c','d','e','f','g','h','i','j','k','m','l','n','o','p','q','r','s','t','u','v','w','x','y','z',
        'A','B','C','D','E','F','G','H','I','J','K','M','L','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'
    };

    private static BPUtil bpUtil;

    public static BPUtil getInstance() {
        if(bpUtil == null)
            bpUtil = new BPUtil();
        return bpUtil;
    }

//            width="60" height="30"
//              base_padding_left="5"
//            range_padding_left="10"
//            base_padding_top="15"
//            range_padding_top="10"
//            codeLength="4"
//            line_number="3"
//            font_size="20"

    //default settings
    private static final int DEFAULT_CODE_LENGTH = ;
    private static final int DEFAULT_FONT_SIZE = ;
    private static final int DEFAULT_LINE_NUMBER = ;
    private static final int BASE_PADDING_LEFT = , RANGE_PADDING_LEFT = , BASE_PADDING_TOP = , RANGE_PADDING_TOP = ;
    private static final int DEFAULT_WIDTH = , DEFAULT_HEIGHT = ;

    //settings decided by the layout xml
    //canvas width and height
    private int width = DEFAULT_WIDTH, height = DEFAULT_HEIGHT; 

    //random word space and pading_top
    private int base_padding_left = BASE_PADDING_LEFT, range_padding_left = RANGE_PADDING_LEFT,
            base_padding_top = BASE_PADDING_TOP, range_padding_top = RANGE_PADDING_TOP;

    //number of chars, lines; font size
    private int codeLength = DEFAULT_CODE_LENGTH, line_number = DEFAULT_LINE_NUMBER, font_size = DEFAULT_FONT_SIZE;

    //variables
    private String code;
    private int padding_left, padding_top;
    private Random random = new Random();

    public Bitmap createBitmap() {
        padding_left = ;

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

        code = createCode();

        c.drawColor(Color.WHITE);
        Paint paint = new Paint();
        paint.setTextSize(font_size);

        for (int i = ; i < code.length(); i++) {
            randomTextStyle(paint);
            randomPadding();
            c.drawText(code.charAt(i) + "", padding_left, padding_top, paint);
        }

        for (int i = ; i < line_number; i++) {
            drawLine(c, paint);
        }

        c.save( Canvas.ALL_SAVE_FLAG );//保存
        c.restore();//
        return bp;
    }

    public String getCode() {
         return bpUtil.createCode();
    }

    private String createCode() {
        StringBuilder buffer = new StringBuilder();
        for (int i = ; 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();
        paint.setColor(color);
        canvas.drawLine(startX, startY, stopX, stopY, paint);
    }

    private int randomColor() {
        return randomColor();
    }

    private int randomColor(int rate) {
        int red = random.nextInt() / rate;
        int green = random.nextInt() / rate;
        int blue = random.nextInt() / 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() / ;
        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
//        paint.setStrikeThruText(true); //true为删除线，false为非删除
    }

    private void randomPadding() {
        padding_left += base_padding_left + random.nextInt(range_padding_left);
        padding_top = base_padding_top + random.nextInt(range_padding_top);
    }
}

　　有了二维码，下面我们开始设计我们的功能，这里先简单说一下，我们最终要实现的功能：1、用户正常输入用户名+密码登录；2、当用户连续3次输错密码，要求用户之后必须增加验证码输入验证。下面我们开始功能设计实现，首先是我们的布局文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${relativePackage}.${activityClass}"
    android:orientation="vertical"
    >

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical"
        >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:text="@string/yanzheng" />
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        >
         <TextView
            android:layout_weight="1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/name" />
         <EditText
             android:id="@+id/name"
             android:layout_width="wrap_content"
             android:layout_weight="6"
             android:layout_height="wrap_content"
             android:hint="@string/name_new"
             android:singleLine="true"
             />
     </LinearLayout>
     <LinearLayout
        android:orientation="horizontal"
           android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        >
         <TextView
            android:layout_weight="1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/password" />
         <EditText
             android:id="@+id/pass"
             android:layout_weight="6"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:hint="@string/pass_new"
             android:singleLine="true"
             />
     </LinearLayout>
     <LinearLayout
        android:id="@+id/layout_yanzhengma"
        android:visibility="gone"
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        >
         <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/yanzhengma" />
         <TextView
             android:id="@+id/rander"
            android:layout_weight="1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            />
         <EditText
             android:id="@+id/rander_input"
             android:layout_weight="1"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:singleLine="true"
             />
     </LinearLayout>
     <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        >
         <Button
            android:id="@+id/get"
            android:layout_weight="1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/get" />
         <Button
         　　android:id="@+id/post"
            android:layout_weight="1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/post" />
      </LinearLayout>

      </LinearLayout>

</RelativeLayout>

　　重点的内容来了，我们主Activity代码，大家先看一下吧：

public class MainActivity extends Activity {

    private TextView mytext = null;
    private EditText myname = null;//用户名
    private EditText mypass = null;//密码
    private EditText myrander =  null;//验证码
    private Button mygetbutton = null;//Get方式发送Http请求
    private Button mypostbutton = null;//Post方式发送Http请求
    private LinearLayout myline = null;//控制二维码的显示

    private static int n = 0;//用户输错密码次数统计

    static String name = null;//用户输入的用户名
    static String password = null;//用户输入的密码
    private String edit;//用户输入用户输入的验证码
    private String code;//验证码

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mytext = (TextView)findViewById(R.id.rander);
        myname = (EditText)findViewById(R.id.name);
        mypass = (EditText)findViewById(R.id.pass);
        myrander = (EditText)findViewById(R.id.rander_input);
        mygetbutton = (Button)findViewById(R.id.get);
        mypostbutton = (Button)findViewById(R.id.post);
        myline = (LinearLayout)findViewById(R.id.layout_yanzhengma);

        mygetbutton.setOnClickListener(new mygetbutton());
        mypostbutton.setOnClickListener(new mypostbutton());

    } 

    class mygetbutton implements OnClickListener{

        public void onClick(View v) {

            name = myname.getText().toString();
            password = mypass.getText().toString();

            if(n>=3){//连续三次输错密码
                edit = myrander.getText().toString();
                boolean boo = captcha (code , edit);
                if(boo){
                    new Thread(new Runnable() {

                        public void run() {

                            final boolean flag = SendServer.getsave(name, password);

                            runOnUiThread(new Runnable() {

                                public void run() {
                                    if(flag){
                                        Toast.makeText(MainActivity.this, "登录成功", Toast.LENGTH_SHORT).show();
                                        n=0;
                                    }else{
                                        Toast.makeText(MainActivity.this, "登录失败", Toast.LENGTH_SHORT).show();
                                        n++;
                                        if(n>=3){
                                            myline.setVisibility(View.VISIBLE);
                                        }
                                    }
                                }
                            });

                        }
                    }).start();
                }else{
                    code = BPUtil.getInstance().getCode().toLowerCase();//生成新的二维码
                    mytext.setText(code);//展示在用户面前
                }
            }else{

                new Thread(new Runnable() {

                    public void run() {

                        final boolean flag = SendServer.getsave(name, password);

                        runOnUiThread(new Runnable() {

                            public void run() {
                                if(flag){
                                    Toast.makeText(MainActivity.this, "登录成功", Toast.LENGTH_SHORT).show();
                                    n=0;
                                }else{
                                    Toast.makeText(MainActivity.this, "登录失败", Toast.LENGTH_SHORT).show();
                                    n++;
                                    if(n>=3){
                                        myline.setVisibility(1);
                                        code = BPUtil.getInstance().getCode().toLowerCase();
                                        mytext.setText(code);
                                    }
                                }
                            }
                        });

                    }
                }).start();

            }

        }

    }

    class mypostbutton implements OnClickListener{

        public void onClick(View v) {

            name = myname.getText().toString();
            password = mypass.getText().toString();

            new Thread(new Runnable() {

                public void run() {

                    final boolean flag = SendServer.postsave(name, password);
                    runOnUiThread(new Runnable() {

                        @Override
                        public void run() {
                            if(flag){
                                Toast.makeText(MainActivity.this, "登录成功", Toast.LENGTH_SHORT).show();
                                n=0;
                            }else{
                                Toast.makeText(MainActivity.this, "登录失败", Toast.LENGTH_SHORT).show();
                                n++;
                                if(n>=3){
                                    myline.setVisibility(1);
                                }
                            }
                        }
                    });
                }
            }).start();

        }

    }

    @SuppressLint("ShowToast")
    private boolean captcha (String code , String edit) {

        boolean flag = false; 

        if (code.equals(edit)) {
            flag = true;
        }else {
            flag = false;
            Toast.makeText(MainActivity.this, " 验证码错误", 0).show();

//            imageview.setImageBitmap(bitmap);

        }
        return flag;
    }

    protected void onRestart() {

        super.onRestart();
        n=0;

    }

    protected void onDestroy() {

        super.onDestroy();
        n=0;

    }

}

　　在这里简单介绍一下代码，因为本篇接下来要为大家分享关于Android发送GET、POST请求的知识，这里我写了两个按钮，一个用来通过使用GET方式验证，一个通过使用POST方式验证，功能上是一致的。最后请大家注意一下：红色字体部分，红色字体部分就是我们通过调用上部二维码生成类，生成二维码，然后展示在用户界面。还有就是：onRestart、onDestroy都是Activity的生命周期函数，这里将n归零，方便我们的再次登录体验。好了到这里我们的第一部分就完成了，下面我们开始进入我们本篇的下半部分。

　　关于Android服务器请求，一般有两种方式：GET、POST两种方式，接下来我们就开始一起学习吧。

public class SendServer {

    //GET方式请求
    public static boolean getsave(String name, String password) {

        boolean flag = false;
        HttpURLConnection conn = null;

        try {

            //防止中文乱码
            String username = URLEncoder.encode(name, "UTF-8");
            String userpassword = URLEncoder.encode(password, "UTF-8");

            URL url = new URL("http://10.20.90.3:8080/Register/ManageServlet?"+"name="+username+"&password="+userpassword);
            conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            conn.setConnectTimeout(5000);
            conn.setReadTimeout(5000);

            int responseCode = conn.getResponseCode();

            if(responseCode == 200){
                InputStream is = conn.getInputStream();
                String stu = getStringFromInputStream(is);
                if(stu.equals("登录成功")){
                    flag = true;
                }
            }

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        } finally{
            if(conn != null){
                conn.disconnect();  //关闭连接
            }
        }

        return flag;

    }

    //POST请求
    public static boolean postsave(String name, String password) {
        boolean flag = false;
        HttpURLConnection conn = null;
        try {
            URL url = new URL("http://10.20.90.3:8080/Register/ManageServlet?");
            conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("POST");
            conn.setConnectTimeout(5000);
            conn.setReadTimeout(5000);

            //post请求参数
            String data = "name="+name+"&password="+password;
            OutputStream out = conn.getOutputStream();
            out.write(data.getBytes());
            out.flush();
            out.close();

//            conn.setRequestProperty("Content-Length", 500);//  内容长度设置为500；请求头消息格式设置

            int respon = conn.getResponseCode();
            if(respon == 200){
                InputStream is = conn.getInputStream();
                String stu = getStringFromInputStream(is);
                if(stu.equals("登录成功")){
                    flag = true;
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            if(conn != null){
                conn.disconnect();
            }
        }

        return flag;
    }

    //解析服务返回的请求
    private static String getStringFromInputStream(InputStream is) throws Exception{
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024*8];
        int len = -1;
        while((len = is.read(buffer)) != -1){
            baos.write(buffer, 0, len);
        }
        is.close();

        String html = new String(baos.toByteArray(), "GBK");//接收服务器端的数据时，防止出现中文乱码。

        //String html = baos.toString();

        baos.close();
        return html;

    }

}

　　好了结束了，内容简单，大家自行了解吧。新手学习，高手交流。