聲明：AS版本爲：3.4；JDK版本爲：1.8

1、先看一下項目目錄：

2、新建一個AS項目，創建如上圖所示的目錄結構，然後添加內容：
（1）修改添加布局文件：

activity_main.xml：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".LoginActivity">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:gravity="center"
        android:text="歡迎進入登錄界面!"
        android:textSize="30dp"
        android:textStyle="bold" />

    <TableLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:stretchColumns="1" >

        <TableRow>

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:text="用戶名：" />

            <EditText
                android:id="@+id/username"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:hint="請輸入用戶名！！！" />
        </TableRow>

        <TableRow>

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:text="密碼：" />

            <EditText
                android:id="@+id/password"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:hint="請輸入密碼！！！" />
        </TableRow>

        <TableRow>

            <TextView />

            <LinearLayout>

                <Button
                    android:id="@+id/login"
                    android:layout_width="100dp"
                    android:layout_height="wrap_content"
                    android:text="登錄" />

                <Button
                    android:id="@+id/register"
                    android:layout_width="100dp"
                    android:layout_height="wrap_content"
                    android:text="註冊" />
            </LinearLayout>
        </TableRow>
    </TableLayout>
</LinearLayout>
</android.support.constraint.ConstraintLayout>

activity_register.xml：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".RegisterActivity">
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:gravity="center"
        android:text="歡迎進入註冊界面!"
        android:textSize="30dp"
        android:textStyle="bold" />

    <TableLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:stretchColumns="1" >

        <TableRow >

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:text="用戶名：" />

            <EditText
                android:id="@+id/usernameRegister"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:hint="請輸入用戶名！！！" />
        </TableRow>

        <TableRow >

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:text="密碼：" />

            <EditText
                android:id="@+id/passwordRegister"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:hint="請輸入密碼！！！" />
        </TableRow>

        <TableRow >

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:text="年齡：" />

            <EditText
                android:id="@+id/ageRegister"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:hint="請輸入年齡！！！" />
        </TableRow>

        <TableRow >

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:text="性別："
                android:textSize="20dp" />

            <RadioGroup
                android:id="@+id/sexRegister"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:checkedButton="@+id/woman"
                android:orientation="horizontal" >

                <RadioButton
                    android:id="@+id/nan"
                    android:text="男"
                    android:layout_height="wrap_content"
                    android:layout_width="wrap_content" />

                <RadioButton
                    android:id="@id/woman"
                    android:text="女"
                    android:layout_height="wrap_content"
                    android:layout_width="wrap_content"/>
            </RadioGroup>
        </TableRow>

        <TableRow >

            <TextView />

            <LinearLayout >
                <Button
                    android:id="@+id/Register"
                    android:layout_width="150dp"
                    android:layout_height="wrap_content"
                    android:text="註冊" />
            </LinearLayout>
        </TableRow>
    </TableLayout>

</LinearLayout>
</android.support.constraint.ConstraintLayout>

（2）在service包DatabaseHelper中添加鏈接AS自帶數據庫以及創建表的語句：

package com.example.sqlitelogin.service;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class DatabaseHelper extends SQLiteOpenHelper {
	static String name="user.db";
	static int dbVersion=1;
	public DatabaseHelper(Context context) {
		super(context, name, null, dbVersion);
	}

	public void onCreate(SQLiteDatabase db) {
		String sql="create table user(id integer primary key autoincrement,username varchar(20),password varchar(20),age integer,sex varchar(2))";
		db.execSQL(sql);
	}
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

	}

}

（3）在service包UserService中用sql語句寫登錄註冊功能的實現：

package com.example.sqlitelogin.service;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

import com.example.sqlitelogin.User;


public class UserService {
	private DatabaseHelper dbHelper;
	public UserService(Context context){
		dbHelper=new DatabaseHelper(context);
	}

	public boolean login(String username,String password){
		SQLiteDatabase sdb=dbHelper.getReadableDatabase();
		String sql="select * from user where username=? and password=?";
		Cursor cursor=sdb.rawQuery(sql, new String[]{username,password});		
		if(cursor.moveToFirst()==true){
			cursor.close();
			return true;
		}
		return false;
	}
	public boolean register(User user){
		SQLiteDatabase sdb=dbHelper.getReadableDatabase();
		String sql="insert into user(username,password,age,sex) values(?,?,?,?)";
		Object obj[]={user.getUsername(),user.getPassword(),user.getAge(),user.getSex()};
		sdb.execSQL(sql, obj);	
		return true;
	}
}

（4）在User文件中聲明要用到的表列名的變量，並對其添加get&&set方法：

package com.example.sqlitelogin;

import java.io.Serializable;

public class User implements Serializable{
    private int id;
    private String username;
    private String password;
    private int age;
    private String sex;
    public User() {
        super();
        // TODO Auto-generated constructor stub
    }
    public User(String username, String password, int age, String sex) {
        super();
        this.username = username;
        this.password = password;
        this.age = age;
        this.sex = sex;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", username=" + username + ", password="
                + password + ", age=" + age + ", sex=" + sex + "]";
    }

}

（5）爲註冊功能添加activity組件：

package com.example.sqlitelogin;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;

import com.example.sqlitelogin.service.UserService;

public class RegisterActivity extends AppCompatActivity {

    EditText username;
    EditText password;
    EditText age;
    RadioGroup sex;
    Button register;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);
        findViews();
        register.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                String name=username.getText().toString().trim();
                String pass=password.getText().toString().trim();
                String agestr=age.getText().toString().trim();
                String sexstr=((RadioButton)RegisterActivity.this.findViewById(sex.getCheckedRadioButtonId())).getText().toString();
                Log.i("TAG",name+"_"+pass+"_"+agestr+"_"+sexstr);
                UserService uService=new UserService(RegisterActivity.this);
                User user=new User();
                user.setUsername(name);
                user.setPassword(pass);
                user.setAge(Integer.parseInt(agestr));
                user.setSex(sexstr);
                uService.register(user);
                Toast.makeText(RegisterActivity.this, "註冊成功", Toast.LENGTH_LONG).show();
            }
        });
    }
    private void findViews() {
        username=(EditText) findViewById(R.id.usernameRegister);
        password=(EditText) findViewById(R.id.passwordRegister);
        age=(EditText) findViewById(R.id.ageRegister);
        sex=(RadioGroup) findViewById(R.id.sexRegister);
        register=(Button) findViewById(R.id.Register);
    }

}

（6）爲登錄功能添加activity組件：

package com.example.sqlitelogin;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.example.sqlitelogin.service.UserService;

public class LoginActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);//即activity_login.xml
        findViews();
    }
    private EditText username;
    private EditText password;
    private Button login;
    private Button register;

    private void findViews() {
        username=(EditText) findViewById(R.id.username);
        password=(EditText) findViewById(R.id.password);
        login=(Button) findViewById(R.id.login);
        register=(Button) findViewById(R.id.register);

        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name=username.getText().toString();
                System.out.println(name);
                String pass=password.getText().toString();
                System.out.println(pass);
               
                Log.i("TAG",name+"_"+pass);
                UserService uService=new UserService(LoginActivity.this);
                boolean flag=uService.login(name, pass);

                if(flag){
                    Log.i("TAG","登錄成功");
                    Toast.makeText(LoginActivity.this, "登錄成功", Toast.LENGTH_LONG).show();
                    Intent intent = new Intent(LoginActivity.this,RegisterActivity.class);
                    startActivity(intent);
                }else{
                    Log.i("TAG","登錄失敗");
                    Toast.makeText(LoginActivity.this, "登錄失敗", Toast.LENGTH_LONG).show();
                }
            }
        });
        register.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Intent intent=new Intent(LoginActivity.this,RegisterActivity.class);
                startActivity(intent);
            }
        });
    }
}

3、Androidmanifest.xml清單文件中，程序運行必備的內容一般都已經自動完成添加了。也可以進行修改：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.sqlitelogin">


    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".RegisterActivity">
            <!--<intent-filter>-->
                <!--<action android:name="android.intent.action.MAIN" />-->

                <!--<category android:name="android.intent.category.LAUNCHER" />-->
            <!--</intent-filter>-->
        </activity>

        <activity android:name=".LoginActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <!--<uses-library android:name="android.test.runner"/>-->
    </application>

</manifest>

4、在模擬器或者真機運行程序，即可！一個連接數據庫的登錄註冊功能已經實現，效果如下：

補：

如果登錄、註冊的兩個佈局文件的 Preview 視圖標紅，將 android.support.constraint.ConstraintLayout 替換爲 LinearLayout 即可

源碼下載：

點擊查看

查看創建的數據庫以及插入的表數據：

點擊查看


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Android Studio一個連接SQLite數據庫的登錄註冊實現

補：

源碼下載：

查看創建的數據庫以及插入的表數據：

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