Android实现登录界面和功能实例

近期⼀个android⼩程序须要登录功能，我简单实现了⼀下。如今记录下来也当做个笔记，同⼀时候也希望能够相互学习。所以，假设我的代码有问题，还各位请提出来。多谢了！

以下。就简述⼀下此实例的主要内容：

输⼊username和password 。从本地⽂件userinfo.json中读取users。推断此username是否在users中，假设不在则增加users，每次退出Activity都使⽤AES算法加密users。然后保存到userinfo.json中。username下拉菜单是由PopupWindow + ListView 实现。

执⾏效果图：

基本的代码：1、⽤户类User

package com.example.logindemo;import org.json.JSONException;import org.json.JSONObject;import android.util.Log;

public class User { private String mId; private String mPwd;

private static final String masterPassword = \"FORYOU\"; // AES加密算法的种⼦ private static final String JSON_ID = \"user_id\";

private static final String JSON_PWD = \"user_pwd\"; private static final String TAG = \"User\"; public User(String id, String pwd) { this.mId = id;

this.mPwd = pwd; }

public User(JSONObject json) throws Exception { if (json.has(JSON_ID)) {

String id = json.getString(JSON_ID);

String pwd = json.getString(JSON_PWD); // 解密后存放

mId = AESUtils.decrypt(masterPassword, id);

mPwd = AESUtils.decrypt(masterPassword, pwd); } }

public JSONObject toJSON() throws Exception { // 使⽤AES加密算法加密后保存

String id = AESUtils.encrypt(masterPassword, mId);

String pwd = AESUtils.encrypt(masterPassword, mPwd); Log.i(TAG, \"加密后:\" + id + \" \" + pwd); JSONObject json = new JSONObject(); try {

json.put(JSON_ID, id);

json.put(JSON_PWD, pwd); } catch (JSONException e) { e.printStackTrace(); }

return json; }

public String getId() { return mId; }

public String getPwd() { return mPwd; }}

2、保存和载⼊本地User列表

package com.example.logindemo;import java.io.BufferedReader;import java.io.FileInputStream;

import java.io.FileNotFoundException;import java.io.IOException;

import java.io.InputStreamReader;import java.io.OutputStream;

import java.io.OutputStreamWriter;import java.io.Writer;import java.util.ArrayList;import org.json.JSONArray;

import org.json.JSONException;import org.json.JSONTokener;import android.content.Context;import android.util.Log;public class Utils {

private static final String FILENAME = \"userinfo.json\"; // ⽤户保存⽂件名称 private static final String TAG = \"Utils\";

/* 保存⽤户登录信息列表 */

public static void saveUserList(Context context, ArrayList users) throws Exception { /* 保存 */

Log.i(TAG, \"正在保存\"); Writer writer = null;

OutputStream out = null;

JSONArray array = new JSONArray(); for (User user : users) { array.put(user.toJSON()); } try {

out = context.openFileOutput(FILENAME, Context.MODE_PRIVATE); // 覆盖 writer = new OutputStreamWriter(out); Log.i(TAG, \"json的值:\" + array.toString()); writer.write(array.toString()); } finally {

if (writer != null) writer.close(); } }

/* 获取⽤户登录信息列表 */

public static ArrayList getUserList(Context context) { /* 载⼊ */

FileInputStream in = null;

ArrayList users = new ArrayList(); try {

in = context.openFileInput(FILENAME);

BufferedReader reader = new BufferedReader( new InputStreamReader(in));

StringBuilder jsonString = new StringBuilder(); JSONArray jsonArray = new JSONArray(); String line;

while ((line = reader.readLine()) != null) { jsonString.append(line); }

Log.i(TAG, jsonString.toString());

jsonArray = (JSONArray) new JSONTokener(jsonString.toString()) .nextValue(); // 把字符串转换成JSONArray对象 for (int i = 0; i < jsonArray.length(); i++) {

User user = new User(jsonArray.getJSONObject(i)); users.add(user); }

} catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace();

} catch (JSONException e) { e.printStackTrace(); } catch (Exception e) { e.printStackTrace(); }

return users; }}

3、AES加密/解密

package com.example.logindemo;

import java.security.SecureRandom;import javax.crypto.Cipher;

import javax.crypto.KeyGenerator;import javax.crypto.SecretKey;

import javax.crypto.spec.IvParameterSpec;import javax.crypto.spec.SecretKeySpec;

public class AESUtils {

public static String encrypt(String seed, String cleartext) throws Exception {

byte[] rawKey = getRawKey(seed.getBytes());

byte[] result = encrypt(rawKey, cleartext.getBytes()); return toHex(result); }

public static String decrypt(String seed, String encrypted) throws Exception {

byte[] rawKey = getRawKey(seed.getBytes()); byte[] enc = toByte(encrypted);

byte[] result = decrypt(rawKey, enc); return new String(result); }

private static byte[] getRawKey(byte[] seed) throws Exception { KeyGenerator kgen = KeyGenerator.getInstance(\"AES\");

SecureRandom sr = SecureRandom.getInstance(\"SHA1PRNG\ sr.setSeed(seed); kgen.init(128, sr);

SecretKey skey = kgen.generateKey(); byte[] raw = skey.getEncoded(); return raw; }

private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception { SecretKeySpec skeySpec = new SecretKeySpec(raw, \"AES\"); Cipher cipher = Cipher.getInstance(\"AES\");

cipher.init(Cipher.ENCRYPT_MODE, skeySpec, new IvParameterSpec( new byte[cipher.getBlockSize()]));

byte[] encrypted = cipher.doFinal(clear); return encrypted; }

private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {

SecretKeySpec skeySpec = new SecretKeySpec(raw, \"AES\"); Cipher cipher = Cipher.getInstance(\"AES\");

cipher.init(Cipher.DECRYPT_MODE, skeySpec, new IvParameterSpec( new byte[cipher.getBlockSize()]));

byte[] decrypted = cipher.doFinal(encrypted); return decrypted; }

private static String toHex(String txt) { return toHex(txt.getBytes()); }

private static String fromHex(String hex) { return new String(toByte(hex)); }

private static byte[] toByte(String hexString) { int len = hexString.length() / 2; byte[] result = new byte[len]; for (int i = 0; i < len; i++)

result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2), 16).byteValue(); return result; }

private static String toHex(byte[] buf) { if (buf == null) return \"\";

StringBuffer result = new StringBuffer(2 * buf.length); for (int i = 0; i < buf.length; i++) {

appendHex(result, buf[i]); }

return result.toString(); }

private final static String HEX = \"01234567ABCDEF\";

private static void appendHex(StringBuffer sb, byte b) {

sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f)); }}

4、LoginActivity.java

package com.example.logindemo;import java.util.ArrayList;

import android.app.Activity;import android.app.Dialog;

import android.graphics.drawable.ColorDrawable;import android.os.Bundle;import android.text.Editable;

import android.text.TextWatcher;import android.util.DisplayMetrics;import android.util.Log;import android.view.View;

import android.view.ViewGroup;import android.view.Window;

import android.view.WindowManager;

import android.view.View.OnClickListener;

import android.view.ViewGroup.LayoutParams;import android.view.animation.Animation;import android.view.animation.AnimationUtils;import android.widget.AdapterView;

import android.widget.AdapterView.OnItemClickListener;import android.widget.ArrayAdapter;import android.widget.Button;import android.widget.EditText;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.ListView;

import android.widget.PopupWindow;

import android.widget.PopupWindow.OnDismissListener;import android.widget.TextView;import android.widget.Toast;

public class LoginActivity extends Activity implements OnClickListener, OnItemClickListener, OnDismissListener {

protected static final String TAG = \"LoginActivity\";

private LinearLayout mLoginLinearLayout; // 登录内容的容器

private LinearLayout mUserIdLinearLayout; // 将下拉弹出窗体在此容器下⽅显⽰ private Animation mTranslate; // 位移动画

private Dialog mLoginingDlg; // 显⽰正在登录的Dialog private EditText mIdEditText; // 登录ID编辑框

private EditText mPwdEditText; // 登录password编辑框 private ImageView mMoreUser; // 下拉图标 private Button mLoginButton; // 登录button

private ImageView mLoginMoreUserView; // 弹出下拉弹出窗的button private String mIdString; private String mPwdString;

private ArrayList mUsers; // ⽤户列表

private ListView mUserIdListView; // 下拉弹出窗显⽰的ListView对象 private MyAapter mAdapter; // ListView的 private PopupWindow mPop; // 下拉弹出窗

@Override

public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_login); initView(); setListener();

mLoginLinearLayout.startAnimation(mTranslate); // Y轴⽔平移动 /* 获取已经保存好的⽤户password */

mUsers = Utils.getUserList(LoginActivity.this); if (mUsers.size() > 0) {

/* 将列表中的第⼀个user显⽰在编辑框 */ mIdEditText.setText(mUsers.get(0).getId());

mPwdEditText.setText(mUsers.get(0).getPwd());

}

LinearLayout parent = (LinearLayout) getLayoutInflater().inflate( R.layout.userifo_listview, null);

mUserIdListView = (ListView) parent.findViewById(android.R.id.list); parent.removeView(mUserIdListView); // 必须脱离⽗⼦关系,不然会报错 mUserIdListView.setOnItemClickListener(this); // 设置点击事 mAdapter = new MyAapter(mUsers); mUserIdListView.setAdapter(mAdapter); }

/* ListView的适配器 */

class MyAapter extends ArrayAdapter { public MyAapter(ArrayList users) { super(LoginActivity.this, 0, users); }

public View getView(final int position, View convertView, ViewGroup parent) { if (convertView == null) {

convertView = getLayoutInflater().inflate( R.layout.listview_item, null); }

TextView userIdText = (TextView) convertView .findViewById(R.id.listview_userid);

userIdText.setText(getItem(position).getId());

ImageView deleteUser = (ImageView) convertView .findViewById(R.id.login_delete_user);

deleteUser.setOnClickListener(new OnClickListener() { // 点击删除deleteUser时,在mUsers中删除选中的元素 @Override

public void onClick(View v) {

if (getItem(position).getId().equals(mIdString)) {

// 假设要删除的⽤户Id和Id编辑框当前值相等，则清空 mIdString = \"\"; mPwdString = \"\";

mIdEditText.setText(mIdString);

mPwdEditText.setText(mPwdString); }

mUsers.remove(getItem(position));

mAdapter.notifyDataSetChanged(); // 更新ListView } });

return convertView; } }

private void setListener() {

mIdEditText.addTextChangedListener(new TextWatcher() { public void onTextChanged(CharSequence s, int start, int before, int count) {

mIdString = s.toString(); }

public void beforeTextChanged(CharSequence s, int start, int count, int after) { }

public void afterTextChanged(Editable s) { } });

mPwdEditText.addTextChangedListener(new TextWatcher() { public void onTextChanged(CharSequence s, int start, int before, int count) {

mPwdString = s.toString(); }

public void beforeTextChanged(CharSequence s, int start, int count, int after) { }

public void afterTextChanged(Editable s) { } });

mLoginButton.setOnClickListener(this);

mLoginMoreUserView.setOnClickListener(this);

}

private void initView() {

mIdEditText = (EditText) findViewById(R.id.login_edtId);

mPwdEditText = (EditText) findViewById(R.id.login_edtPwd); mMoreUser = (ImageView) findViewById(R.id.login_more_user); mLoginButton = (Button) findViewById(R.id.login_btnLogin);

mLoginMoreUserView = (ImageView) findViewById(R.id.login_more_user); mLoginLinearLayout = (LinearLayout) findViewById(R.id.login_linearLayout); mUserIdLinearLayout = (LinearLayout) findViewById(R.id.userId_LinearLayout);

mTranslate = AnimationUtils.loadAnimation(this, R.anim.my_translate); // 初始化动画对象 initLoginingDlg(); }

public void initPop() {

int width = mUserIdLinearLayout.getWidth() - 4; int height = LayoutParams.WRAP_CONTENT;

mPop = new PopupWindow(mUserIdListView, width, height, true); mPop.setOnDismissListener(this);// 设置弹出窗体消失时 // 注意要加这句代码，点击弹出窗体其他区域才会让窗体消失 mPop.setBackgroundDrawable(new ColorDrawable(0xffffffff)); }

/* 初始化正在登录对话框 */ private void initLoginingDlg() {

mLoginingDlg = new Dialog(this, R.style.loginingDlg); mLoginingDlg.setContentView(R.layout.logining_dlg);

Window window = mLoginingDlg.getWindow();

WindowManager.LayoutParams params = window.getAttributes();

// 获取和mLoginingDlg关联的当前窗体的属性，从⽽设置它在屏幕中显⽰的位置 // 获取屏幕的⾼宽

DisplayMetrics dm = new DisplayMetrics();

getWindowManager().getDefaultDisplay().getMetrics(dm); int cxScreen = dm.widthPixels; int cyScreen = dm.heightPixels;

int height = (int) getResources().getDimension( R.dimen.loginingdlg_height);// ⾼42dp

int lrMargin = (int) getResources().getDimension( R.dimen.loginingdlg_lr_margin); // 左右边沿10dp int topMargin = (int) getResources().getDimension( R.dimen.loginingdlg_top_margin); // 上沿20dp

params.y = (-(cyScreen - height) / 2) + topMargin; // -199

/* 对话框默认位置在屏幕中⼼,所以x,y表⽰此控件到\"屏幕中⼼\"的偏移量 */ params.width = cxScreen; params.height = height;

// width,height表⽰mLoginingDlg的实际⼤⼩

mLoginingDlg.setCanceledOnTouchOutside(true); // 设置点击Dialog外部随意区域关闭Dialog }

/* 显⽰正在登录对话框 */

private void showLoginingDlg() { if (mLoginingDlg != null) mLoginingDlg.show(); }

/* 关闭正在登录对话框 */

private void closeLoginingDlg() {

if (mLoginingDlg != null && mLoginingDlg.isShowing()) mLoginingDlg.dismiss(); }

@Override

public void onClick(View v) { switch (v.getId()) {

case R.id.login_btnLogin: // 启动登录

showLoginingDlg(); // 显⽰\"正在登录\"对话框,由于此Demo没有登录到webserver,所以效果可能看不出.能够结合情况使⽤ Log.i(TAG, mIdString + \" \" + mPwdString);

if (mIdString == null || mIdString.equals(\"\")) { // 账号为空时

Toast.makeText(LoginActivity.this, \"请输⼊账号\ .show();

} else if (mPwdString == null || mPwdString.equals(\"\")) {// password为空时

Toast.makeText(LoginActivity.this, \"请输⼊password\ .show();

} else {// 账号和password都不为空时

boolean mIsSave = true; try {

Log.i(TAG, \"保存⽤户列表\");

for (User user : mUsers) { // 推断本地⽂档是否有此ID⽤户 if (user.getId().equals(mIdString)) { mIsSave = false; break; } }

if (mIsSave) { // 将新⽤户增加users

User user = new User(mIdString, mPwdString); mUsers.add(user); }

} catch (Exception e) { e.printStackTrace(); }

closeLoginingDlg();// 关闭对话框

Toast.makeText(this, \"登录成功\ finish(); }

break;

case R.id.login_more_user: // 当点击下拉栏 if (mPop == null) { initPop(); }

if (!mPop.isShowing() && mUsers.size() > 0) { // Log.i(TAG, \"切换为⾓向上图标\");

mMoreUser.setImageResource(R.drawable.login_more_down); // 切换图标 mPop.showAsDropDown(mUserIdLinearLayout, 2, 1); // 显⽰弹出窗体 }

break; default: break; } }

@Override

public void onItemClick(AdapterView parent, View view, int position, long id) {

mIdEditText.setText(mUsers.get(position).getId());

mPwdEditText.setText(mUsers.get(position).getPwd()); mPop.dismiss(); }

/* PopupWindow对象dismiss时的事件 */ @Override

public void onDismiss() {

// Log.i(TAG, \"切换为⾓向下图标\");

mMoreUser.setImageResource(R.drawable.login_more_up); }

/* 退出此Activity时保存users */ @Override

public void onPause() { super.onPause(); try {

Utils.saveUserList(LoginActivity.this, mUsers); } catch (Exception e) { e.printStackTrace(); } }}

其它⼀些布局和资源配置我就不具体列出了，想看的能够下载