Android 连接数据库
1.添加新用户。
2.在libs中导入mysql的jar包。
3. 修改AndroidManifest.xml，代码如下。
1 <?xml version="1.0" encoding="utf-8"?> 2 <manifest xmlns:android="http://schemas.android.com/apk/res/android" 3 xmlns:tools="http://schemas.android.com/tools"> 4 5 <uses-permission android:name="android.permission.INTERNET" /> 6 7 <application 8 9 android:allowBackup="true" 10 android:dataExtractionRules="@xml/data_extraction_rules" 11 android:fullBackupContent="@xml/backup_rules" 12 android:icon="@mipmap/ic_launcher" 13 android:label="@string/app_name" 14 android:supportsRtl="true" 15 android:theme="@style/Theme.MyApplication" 16 tools:targetApi="31"> 17 44 <activity 45 android:name=".MainActivity" 46 android:exported="true"> 47 <intent-filter> 48 <action android:name="android.intent.action.MAIN" /> 49 50 <category android:name="android.intent.category.LAUNCHER" /> 51 </intent-filter> 52 </activity> 53 </application> 54 55 </manifest>
4.写一个登录界面
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 xmlns:app="http://schemas.android.com/apk/res-auto" 4 xmlns:tools="http://schemas.android.com/tools" 5 android:layout_width="match_parent" 6 android:layout_height="match_parent" 7 android:orientation="vertical" 8 android:layout_gravity="center" 9 android:layout_margin="16dp" 10 tools:context=".MainActivity"> 11 12 <GridLayout 13 android:layout_width="match_parent" 14 android:layout_height="wrap_content" 15 android:columnCount="2"> 16 17 <TextView 18 android:layout_width="wrap_content" 19 android:layout_height="wrap_content" 20 android:text="账号" 21 android:textSize="20sp" 22 android:gravity="center" 23 24 /> 25 26 <EditText 27 android:id="@+id/et_username" 28 android:layout_width="match_parent" 29 android:layout_height="wrap_content"/> 30 31 </GridLayout> 32 33 34 35 36 37 <GridLayout 38 android:layout_width="match_parent" 39 android:layout_height="wrap_content" 40 android:columnCount="2"> 41 42 <TextView 43 android:layout_width="wrap_content" 44 android:layout_height="wrap_content" 45 android:text="密码" 46 android:textSize="20sp" 47 android:gravity="center" 48 49 /> 50 51 <EditText 52 android:id="@+id/et_password" 53 android:layout_width="match_parent" 54 android:layout_height="wrap_content" 55 /> 56 57 </GridLayout> 58 59 <Button 60 android:id="@+id/btn_login" 61 android:layout_width="match_parent" 62 android:layout_height="wrap_content" 63 android:text="登录" 64 /> 65 66 <Button 67 android:id="@+id/btn_sub" 68 android:text="注册" 69 android:layout_width="match_parent" 70 android:layout_height="wrap_content" 71 /> 72 73 74 </LinearLayout>
4 建一个mysql包，建一个MySqlHelper
1 public class MySqlHelper { 2 public static Connection getConnection() { 3 try { 4 5 Class.forName("com.mysql.jdbc.Driver"); 6 } catch ( ClassNotFoundException e) { 7 // TODO Auto-generated catch block 8 e.printStackTrace(); 9 Log.d(TAG,"yc"); 10 } 11 String user = "as_root"; 12 String password = "123456"; 13 String url = "jdbc:mysql://172.20.10.2:3306/db1?useSSL=false"; //ipv4地址会变，注意修正 14 Connection connection = null; 15 try { 16 17 connection = DriverManager.getConnection(url,user,password); 18 } catch (SQLException e) { 19 // TODO Auto-generated catch block 20 e.printStackTrace(); 21 Log.d(TAG,"yc2"); 22 } catch (Exception ex){ 23 ex.printStackTrace(); 24 } 25 return connection; 26 } 27 28 29 public static void close(Connection connection ) { 30 try { 31 if (connection != null) { 32 connection.close(); 33 } 34 35 } catch (SQLException e) { 36 // TODO Auto-generated catch block 37 e.printStackTrace(); 38 } 39 } 40 41 public static void close(PreparedStatement preparedStatement ) { 42 try { 43 if (preparedStatement != null) { 44 preparedStatement.close(); 45 } 46 47 } catch (SQLException e) { 48 // TODO Auto-generated catch block 49 e.printStackTrace(); 50 } 51 } 52 53 public static void close(ResultSet resultSet ) { 54 try { 55 if (resultSet != null) { 56 resultSet.close(); 57 } 58 59 } catch (SQLException e) { 60 // TODO Auto-generated catch block 61 e.printStackTrace(); 62 } 63 } 64 65 }
5.在mysql包下建立DBmanage，里面写入mysql操作。（注册案例）
1 public class DBmanager { 2 private Connection connection; 3 private ResultSet resultSet; 4 private PreparedStatement preparedStatement; 5 6 //关闭数据库 7 public void close(Connection connection, ResultSet resultSet, PreparedStatement preparedStatement) { 8 MySqlHelper.close(connection); 9 MySqlHelper.close(resultSet); 10 MySqlHelper.close(preparedStatement); 11 } 12 //注册用户 13 public void sub_register(String userid,String username, String password,String classname,String role,String phone) { 14 Connection connection; 15 ResultSet resultSet; 16 PreparedStatement preparedStatement; 17 18 try { 19 connection = MySqlHelper.getConnection(); 20 resultSet = null; 21 preparedStatement = null; 22 23 String sql = "insert into tb_user (userid,username, password,classname,role,phone) values (?,?,?,?,?,?)"; 24 //String sql = "delete from tb_user where username = ?"; 25 preparedStatement = connection.prepareStatement(sql); 26 //Log.d(TAG,ui.getStu_class()); 27 preparedStatement.setString(1, userid); 28 preparedStatement.setString(2, username); 29 preparedStatement.setString(3, password); 30 preparedStatement.setString(4, classname); 31 preparedStatement.setString(5, role); 32 preparedStatement.setString(6, phone); 33 //Log.d(TAG,ui.getStu_id()); 34 preparedStatement.executeUpdate(); 35 36 } catch (Exception ex) { 37 ex.printStackTrace(); 38 39 } 40 41 } 42 }
6.主页面代码如下
1 public class MainActivity extends AppCompatActivity implements View.OnClickListener { 2 3 private EditText et_username; 4 private EditText et_password; 5 private Button btn_sub; 6 private Button btn_login; 7 private String role; 8 9 10 @Override 11 protected void onCreate(Bundle savedInstanceState) { 12 super.onCreate(savedInstanceState); 13 setContentView(R.layout.activity_main); 14 15 initView(); 16 17 } 18 19 private void initView() { 20 21 et_username = findViewById(R.id.et_username); 22 et_password = findViewById(R.id.et_password); 23 24 btn_sub = findViewById(R.id.btn_sub); 25 btn_login = findViewById(R.id.btn_login); 26 27 28 btn_sub.setOnClickListener(this); 29 btn_login.setOnClickListener(this); 30 31 32 //设置默认值、 33 String namepaw = DBManager_lite.getLogin(); 34 String username = " ", password = " "; 35 String[] parts = namepaw.split("-"); 36 37 if(parts.length == 2) { 38 username = parts[0].toString(); 39 password = parts[1].toString(); 40 } 41 et_username.setText(username); 42 et_password.setText(password); 43 44 45 46 } 47 48 @Override 49 public void onClick(View view) { 50 if (view.getId() == R.id.btn_sub){ 51 52 Intent intent = new Intent(MainActivity.this, MainActivity_regist.class); 53 54 String username=et_username.getText().toString(); 55 intent.putExtra("username", username); //将用户名传到下一个页面 56 57 startActivity(intent); 58 59 //插入MYSQL 60 // Sub_register.sub_reg(et_username.getText().toString(), et_password.getText().toString()); 61 // //插入SQLITE 62 // DBManager_lite.insertInfo(et_username.getText().toString(), et_password.getText().toString()); 63 // Intent intent = new Intent(MainActivity.this, MainActivity.class); 64 // startActivity(intent); 65 66 } else if (view.getId() == R.id.btn_login) { 67 String username = et_username.getText().toString(); 68 String password = et_password.getText().toString(); 69 role = DoLogin.dologin(username, password); 70 if(role.equals("student")){ 71 Intent intent = new Intent(MainActivity.this, MainActivity_menu.class); 72 intent.putExtra("username", username); //将用户名传到下一个页面 73 startActivity(intent); 74 } else if(role.equals("teacher")){ 75 76 Intent intent = new Intent(MainActivity.this, MainActivity_tea_menu.class); 77 intent.putExtra("username", username); //将用户名传到下一个页面 78 startActivity(intent); 79 } 80 else { 81 // 登录失败，显示用户名或密码错误 82 Toast.makeText(MainActivity.this, "用户名或密码错误", Toast.LENGTH_SHORT).show(); 83 } 84 } 85 86 87 } 88 }
7 建一个包DAO，里面写入相应的类 （注册案例），调用mysql下的DBmanager中的类。
1 public class Sub_register { 2 public static void sub_reg(String userid,String username, String password,String classname,String role,String phone){ 3 new Thread(new Runnable() { 4 @Override 5 public void run() { 6 DBmanager db = new DBmanager(); 7 db.sub_register( userid,username,password,classname,role,phone); 8 9 } 10 }).start(); 11 } 12 }
