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 = {
'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 );//保存
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
//        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。