Android Studio一个连接SQLite数据库的登录注册实现

声明：AS版本为：3.4；JDK版本为：1.8

1、先看一下项目目录：

2、新建一个AS项目，创建如上图所示的目录结构，然后添加内容：
（1）修改添加布局文件：

• activity_main.xml：

• activity_register.xml：

（2）在service包DatabaseHelper中添加链接AS自带数据库以及创建表的语句：

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语句写登录注册功能的实现：

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文件中声明要用到的表列名的变量，并对其添加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）为注册功能添加activity组件：

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, "注册成功", 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）为登录功能添加activity组件：

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","登录成功");
                    Toast.makeText(LoginActivity.this, "登录成功", Toast.LENGTH_LONG).show();
                    Intent intent = new Intent(LoginActivity.this,RegisterActivity.class);
                    startActivity(intent);
                }else{
                    Log.i("TAG","登录失败");
                    Toast.makeText(LoginActivity.this, "登录失败", 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清单文件中，程序运行必备的内容一般都已经自动完成添加了。也可以进行修改：

4、在模拟器或者真机运行程序，即可！一个连接数据库的登录注册功能已经实现，效果如下：

补：

如果登录、注册的两个布局文件的 Preview 视图标红，将 android.support.constraint.ConstraintLayout 替换为 LinearLayout 即可

源码下载：

点击查看

查看创建的数据库以及插入的表数据：

点击查看

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