Android之登入那點事

　　随着網際網路的高速發展，一個應用為了保護使用者的隐私，通常會通過設定使用者名+密碼的驗證方式保證使用者隐私的相對安全，我知道一般網站的登入驗證，通常會設定一個二維碼，通過驗證二維碼，防止惡意軟體通過機械程式，對使用者密碼進行破解，那麼Android裝置如何實作這個功能呢？相信很多開發者對此不屑一顧，因為這樣增加了使用者使用的複雜性，很多軟體是不會這樣設計的，現在我們暫且不談它是不是有用，今天我們重點探讨一下，如何在Android的裝置上實作這個功能。本篇為大家介紹的内容包括：1、使用者連續多次輸錯密碼，增加驗證碼驗證；2、Android如何通過http請求達到與伺服器之間的通訊。好了下面開始我們今天内容的介紹，首先我們先一起來學習一下如何實作使用者連續多次輸錯密碼，增加驗證碼功能。

　　既然用的到二維碼，那麼Android如何生成二維碼呢？為大家提供一個生成二維碼的類：

//生成二維碼的類
public class BPUtil {
    
    /**
     * 用于生成二維碼的字元
     */
    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','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 = 4;
    private static final int DEFAULT_FONT_SIZE = 20;
    private static final int DEFAULT_LINE_NUMBER = 3;
    private static final int BASE_PADDING_LEFT = 5, RANGE_PADDING_LEFT = 10, BASE_PADDING_TOP = 15, RANGE_PADDING_TOP = 10;
    private static final int DEFAULT_WIDTH = 60, DEFAULT_HEIGHT = 30;
    
    //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 = 0;
        
        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 = 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 );//儲存  
        c.restore();//
        return bp;
    }
    
    public String getCode() {
         return bpUtil.createCode();
    }
    
    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為粗體，false為非粗體
        float skewX = random.nextInt(11) / 10;
        skewX = random.nextBoolean() ? skewX : -skewX;
        paint.setTextSkewX(skewX); //float類型參數，負數表示右斜，整數左斜
//        paint.setUnderlineText(true); //true為下劃線，false為非下劃
//        paint.setStrikeThruText(true); //true為删除線，false為非删除
    }
    
    private void randomPadding() {
        padding_left += base_padding_left + random.nextInt(range_padding_left);
        padding_top = base_padding_top + random.nextInt(range_padding_top);
    }
}      

　　有了二維碼，下面我們開始設計我們的功能，這裡先簡單說一下，我們最終要實作的功能：1、使用者正常輸入使用者名+密碼登入；2、當使用者連續3次輸錯密碼，要求使用者之後必須增加驗證碼輸入驗證。下面我們開始功能設計實作，首先是我們的布局檔案：

<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>      

　　重點的内容來了，我們主Activity代碼，大家先看一下吧：

public class MainActivity extends Activity {
    
    private TextView mytext = null;
    private EditText myname = null;//使用者名
    private EditText mypass = null;//密碼
    private EditText myrander =  null;//驗證碼
    private Button mygetbutton = null;//Get方式發送Http請求
    private Button mypostbutton = null;//Post方式發送Http請求
    private LinearLayout myline = null;//控制二維碼的顯示
    
    private static int n = 0;//使用者輸錯密碼次數統計
    
    static String name = null;//使用者輸入的使用者名
    static String password = null;//使用者輸入的密碼
    private String edit;//使用者輸入使用者輸入的驗證碼
    private String code;//驗證碼
    
    @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){//連續三次輸錯密碼
                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, "登入成功", Toast.LENGTH_SHORT).show();
                                        n=0;
                                    }else{
                                        Toast.makeText(MainActivity.this, "登入失敗", Toast.LENGTH_SHORT).show();
                                        n++;
                                        if(n>=3){
                                            myline.setVisibility(View.VISIBLE);
                                        }
                                    }
                                }
                            });
                            
                        }
                    }).start();
                }else{
                    code = BPUtil.getInstance().getCode().toLowerCase();//生成新的二維碼
                    mytext.setText(code);//展示在使用者面前
                }
            }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, "登入成功", Toast.LENGTH_SHORT).show();
                                    n=0;
                                }else{
                                    Toast.makeText(MainActivity.this, "登入失敗", 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, "登入成功", Toast.LENGTH_SHORT).show();
                                n=0;
                            }else{
                                Toast.makeText(MainActivity.this, "登入失敗", 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, " 驗證碼錯誤", 0).show();
            
//            imageview.setImageBitmap(bitmap);
            
        }
        return flag;
    }

    protected void onRestart() {
        
        super.onRestart();
        n=0;
        
    }

    protected void onDestroy() {
        
        super.onDestroy();
        n=0;
        
    }

}      

　　在這裡簡單介紹一下代碼，因為本篇接下來要為大家分享關于Android發送GET、POST請求的知識，這裡我寫了兩個按鈕，一個用來通過使用GET方式驗證，一個通過使用POST方式驗證，功能上是一緻的。最後請大家注意一下：紅色字型部分，紅色字型部分就是我們通過調用上部二維碼生成類，生成二維碼，然後展示在使用者界面。還有就是：onRestart、onDestroy都是Activity的生命周期函數，這裡将n歸零，友善我們的再次登入體驗。好了到這裡我們的第一部分就完成了，下面我們開始進入我們本篇的下半部分。

　　關于Android伺服器請求，一般有兩種方式：GET、POST兩種方式，接下來我們就開始一起學習吧。

public class SendServer {

    //GET方式請求
    public static boolean getsave(String name, String password) {
        
        boolean flag = false;
        HttpURLConnection conn = null;
        
        try {
            
            //防止中文亂碼
            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("登入成功")){
                    flag = true;
                }
            }
            
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        } finally{
            if(conn != null){
                conn.disconnect();  //關閉連接配接
            }
        }
        
        return flag;
        
    }
    
    //POST請求
    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請求參數
            String data = "name="+name+"&password="+password;
            OutputStream out = conn.getOutputStream();
            out.write(data.getBytes());
            out.flush();
            out.close();
            
//            conn.setRequestProperty("Content-Length", 500);//  内容長度設定為500；請求頭消息格式設定
            
            int respon = conn.getResponseCode();
            if(respon == 200){
                InputStream is = conn.getInputStream();
                String stu = getStringFromInputStream(is);
                if(stu.equals("登入成功")){
                    flag = true;
                }
            }
            
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            if(conn != null){
                conn.disconnect();
            }
        }
        
        return flag;
    }
        
    //解析服務傳回的請求
    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");//接收伺服器端的資料時，防止出現中文亂碼。
        
        //String html = baos.toString();
        
        baos.close();
        return html;
        
    }

}      

　　好了結束了，内容簡單，大家自行了解吧。新手學習，高手交流。