2024.4.28

因为我们的程序目标计划改变，现在目标是制作一个出游打卡系统app，所以着手开始新程序，首先是数据库连接和登录
CommonUtils.java
package com.example.share.utils;

import android.content.Context;
import android.widget.Toast;

import androidx.appcompat.app.AlertDialog;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

/**

• 自定义通用工具类
  */
  public class CommonUtils {

  /**

  • 获取当前时间的字符串
  • @return "yyyy-MM-dd HH:mm:ss" 格式的时间字符串
    */
    public static String getDateStrFromNow(){
    DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    return df.format(new Date());
    }

  /**

  • 从日期时间中获取时间字符串
  • @param dt 日期时间
  • @return "yyyy-MM-dd HH:mm:ss" 格式的时间字符串
    */
    public static String getStrFromDate(Date dt){
    DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    return df.format(dt);
    }

  /**

  • 显示短消息
  • @param context 上下文
  • @param msg 要显示的消息
    */
    public static void showShortMsg(Context context, String msg){
    Toast.makeText(context, msg, Toast.LENGTH_SHORT).show();
    }

  /**

  • 显示长消息
  • @param context 上下文
  • @param msg 要显示的消息
    */
    public static void showLonMsg(Context context, String msg){
    Toast.makeText(context, msg, Toast.LENGTH_LONG).show();
    }

  /**

  • 显示消息对话框
  • @param context 上下文
  • @param msg 要显示的消息
    */
    public static void showDlgMsg(Context context, String msg){
    new AlertDialog.Builder(context)
    .setTitle("提示信息")
    .setMessage(msg)
    .setPositiveButton("确定", null)
    .setNegativeButton("取消", null)
    .create().show();
    }
    }
    DbOpenHelper.java
    package com.example.share.utils;

import android.util.Log;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;

public class DbOpenHelper {
private static final String CLS="com.mysql.jdbc.Driver";
private static final String URL="jdbc:mysql://192.168.43.157:3306/tuandui?useSSL=false&serverTimezone=UTC&useUnicode=true&characterEncoding=utf8";
private static final String USER="root";
private static final String PASSWORD="ADGJL12345syl";

public static Connection connection; //连接对象
public static Statement statement; //命令集
public static PreparedStatement preparedStatement; //预编译命令集v
public static ResultSet resultSet; //结果集
//获取连接的方法
public static void getConnection(){
try{
Class.forName(CLS);
connection = DriverManager.getConnection(URL,USER,PASSWORD);

}catch (Exception e){
Log.e("DB_CONNECTION", "Connection Error: " + e.getMessage());
e.printStackTrace();
}
}

public static void closeAll(){
try{
if(connection != null){
connection.close();
connection = null;
}
if(statement != null){
statement.close();
statement = null;
}
if(preparedStatement != null){
preparedStatement.close();
preparedStatement = null;
}
if(resultSet != null){
resultSet.close();
resultSet = null;
}
}catch(Exception e){
e.printStackTrace();
}
}

}
User.java
package com.example.share.entity;

public class User {
private String name;
private String id;
private String password;

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public String getId() {
return id;
}

public void setId(String id) {
this.id = id;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

public User() {
}

public User(String name, String id, String password) {
this.name = name;
this.id = id;
this.password = password;
}
}
UserDao.java
package com.example.share.dao;

import static com.example.share.utils.DbOpenHelper.closeAll;
import static com.example.share.utils.DbOpenHelper.connection;
import static com.example.share.utils.DbOpenHelper.getConnection;

import com.example.share.entity.MyUser;
import com.example.share.utils.DbOpenHelper;

import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class UserDao extends DbOpenHelper {

public int addMyUser(MyUser myUser){

int iRow=0;
try{
getConnection();
String sql = "insert into myuser values(?,?)";
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1,myUser.getName());
preparedStatement.setString(2,myUser.getPasword());
iRow=preparedStatement.executeUpdate();

}catch(Exception e){
e.printStackTrace();
}finally {
closeAll();
}
return iRow;
}

public String login(String name) {
String password = "";
try {
getConnection();
String sql = "select password from myuser where name=?";
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, name);
resultSet = preparedStatement.executeQuery();
if (resultSet.next()) {
password = resultSet.getString("password");
}
} catch (Exception e) {
e.printStackTrace();
} finally {
closeAll();
}
return password;
}
}
Mainactivity.java
package com.example.share;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

//import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;

import com.example.share.register;
import com.example.share.dao.UserDao;
import com.example.share.utils.CommonUtils;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

private Button LoginButton,SignUpButton;
private EditText UserNameEdit,PassWordEdit;
UserDao userDao;
private Handler mainHandler;

@SuppressLint("MissingInflatedId")
@Override
protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

LoginButton = findViewById(R.id.LoginButton);
SignUpButton=findViewById(R.id.SignUpButton);

UserNameEdit = findViewById(R.id.UserNameEdit);
PassWordEdit = findViewById(R.id.PassWordEdit);

userDao=new UserDao();
mainHandler=new Handler(getMainLooper());

LoginButton.setOnClickListener(this);
SignUpButton.setOnClickListener(this);
}

@Override
public void onClick(View v) {
if (v.getId() == R.id.LoginButton) {
String name=UserNameEdit.getText().toString().trim();
String password=PassWordEdit.getText().toString().trim();

new Thread(new Runnable() {
@Override
public void run() {

String Password="";
String TeacherPassword="";
Password=userDao.login(name);

if(password.equals(Password)){
Intent intent=new Intent(getApplicationContext(), DongtaiActivity.class);
Bundle bundle=new Bundle();
bundle.putString("name",name);
intent.putExtras(bundle);
startActivity(intent);
mainHandler.post(new Runnable() {
@Override
public void run() {
CommonUtils.showShortMsg(MainActivity.this,"登陆成功");
SharedPreferences sharedPref = getSharedPreferences("app_prefs", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putString("username", name);
editor.apply();
Intent intent=new Intent(getApplicationContext(), DongtaiActivity.class);
}
});

}
else if(password.equals(TeacherPassword)){
Intent intent=new Intent(getApplicationContext(), DongtaiActivity.class);
startActivity(intent);
mainHandler.post(new Runnable() {
@Override
public void run() {
CommonUtils.showShortMsg(MainActivity.this,"登陆成功");
Intent intent=new Intent(getApplicationContext(), DongtaiActivity.class);
}
});

}
else{
mainHandler.post(new Runnable() {
@Override
public void run() {
CommonUtils.showShortMsg(MainActivity.this,"登陆失败");
}
});
}
}
}).start();
}
else if(v.getId()==R.id.SignUpButton){
Intent intent=new Intent(getApplicationContext(), register.class);
startActivity(intent);
}
}

@Override
public void onPointerCaptureChanged(boolean hasCapture) {
super.onPointerCaptureChanged(hasCapture);
}
}
activity_main.xml

<androidx.constraintlayout.widget.ConstraintLayout 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=".MainActivity">

<androidx.appcompat.widget.AppCompatButton
android:id="@+id/LoginButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="15dp"
android:layout_margin="15dp"
android:layout_weight="1"
android:textColor="@color/white"
android:background="@drawable/translucent_button"
android:text="登 录"
android:textSize="24dp" />

<androidx.appcompat.widget.AppCompatButton
android:id="@+id/SignUpButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="15dp"
android:layout_margin="15dp"
android:layout_weight="1"
android:textColor="@color/white"
android:background="@drawable/translucent_button"
android:text="注 册"
android:textSize="24dp" />

</androidx.constraintlayout.widget.ConstraintLayout>