家庭记账本安卓版开发：第二天

一、结果测试

此时第一次运行，数据库进行创建，数据为空

 

 

我们去注册账号

 输入用户名

输入密码

 

 注册成功，自动返回登录页

 查看数据库

 再次返回注册页，注册名字为zzw，提示用户名已存在

 我们返回登录页去登陆

 登陆成功

 二、问题总结

1、在Activity调用onCreate方法时，应该调用public void onCreate(@Nullable Bundle savedInstanceState)方法，而不是public void onCreate(@Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState)方法。

2、在数据库为空时，进行增删改查，如果调用数据库事务就会报错。

3、当使用startActivityForResult(intent,mRegisterCode);进行跳转时，在第二个界面的跳转回第一个页面的时候，必须要加上finish（），因为这个方法的定义是，当在第二个界面的操作完成后，自动跳回第一个界面，而finish（）就起着判断在第二个Activity的操作是否完成的重要作用，只要不finish，那就不会跳转回来。

三、原码

 AndroidManifest.xml

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

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="家庭记账本"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".LoginActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".IndexActivity"/>
        <activity android:name=".RegisterActivity"/>
    </application>

</manifest>

LoginActivity.java

package com.example.familybook;

import android.content.Intent;
import android.os.Bundle;
import android.os.PersistableBundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;


import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

import com.example.familybook.dao.IUserDao;
import com.example.familybook.dao.UserDaoImpl;
import com.example.familybook.database.UserDatabaseHelper;

public class LoginActivity  extends AppCompatActivity {

    private EditText mUsername;
    private EditText mPassword;
    private Button mLogin;
    private Button mGotoregister;
    private  static final int mRegisterCode=1;
    private IUserDao mIUserDao;


    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        //创建数据库
        UserDatabaseHelper helper =new UserDatabaseHelper(LoginActivity.this);
        helper.getWritableDatabase();

        //初始化控件
        initView();
        //设置事件监听
        initListener();
    }

    private void initListener() {
        mLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                login();
            }
        });
        mGotoregister.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                register();
            }
        });
    }

    private void register() {
        Intent intent =new Intent(this, RegisterActivity.class);
        startActivityForResult(intent,mRegisterCode);
    }

    private void login() {
        //账号
        String usernameText =mUsername.getText().toString();
        //密码
        String passwordText =mPassword.getText().toString();

        //对账号和密码进行检测
        if(TextUtils.isEmpty(usernameText)){
            //账号为空
            Toast.makeText(this,"用户名不可以为空",Toast.LENGTH_SHORT).show();
            return;
        }else if(TextUtils.isEmpty(passwordText)){
            //密码为空
            Toast.makeText(this,"密码不可以为空",Toast.LENGTH_SHORT).show();
        }else {
            boolean result = mIUserDao.Login(usernameText, passwordText);
            if (result) {

                Intent intent = new Intent(this, IndexActivity.class);
                startActivity(intent);
            } else {
                //登录失败
                Toast.makeText(this, "用户名或密码错误", Toast.LENGTH_SHORT).show();
            }
        }
    }

    private void initView() {
        mUsername=(EditText)this.findViewById(R.id.username);
        mPassword=(EditText)this.findViewById(R.id.password);
        mLogin=(Button) this.findViewById(R.id.login_btn);
        mGotoregister=(Button)this.findViewById(R.id.goto_register_btn);
        mIUserDao=new UserDaoImpl(this);
    }
    /**
     * 返回的结果在这里回调
     * @param requestCode
     * @param resultCode
     * @param data
     */
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        String resultContent = null;
        //当我们判断这个请求码的时候，就知道，这是注册界面返回的结果
        if (requestCode==mRegisterCode) {
            if(resultCode==2){
                //注册成功
                Toast.makeText(this,"注册成功",Toast.LENGTH_SHORT).show();
            }
        }
    }

}

RegisterActivity.java

package com.example.familybook;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
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 androidx.annotation.Nullable;

import com.example.familybook.dao.IUserDao;
import com.example.familybook.dao.UserDaoImpl;
import com.example.familybook.entity.User;
public class RegisterActivity extends Activity{


        private RadioGroup mSex;
        private EditText mUsername;
        private EditText mPassword;
        private Button mRegisterBtn;
        private RadioButton mR;
        private IUserDao mIUserDao;
        private String TAG="RegisterActivity";

    @Override
        public void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_register);
            //初始化控件
            initView();
            //设置监听，处理点击事件
            initListener();
        }

        private void initListener() {
            mSex.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
                @Override
                public void onCheckedChanged(RadioGroup group, int checkedId) {
                    mR =(RadioButton) findViewById(checkedId);
                }
            });
            mRegisterBtn.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    //点击了注册按钮
                    Registerhandler();
                }
            });
        }

        private void Registerhandler() {
            User user =null;
            //账号
            String usernameText =mUsername.getText().toString().trim();
            //密码
            String passwordText =mPassword.getText().toString().trim();
            //性别
            String sexText;
            if(mR.getText().toString()!=null) {
                 sexText = mR.getText().toString();
            }else{
                sexText="男";
            }
            Log.e(TAG,"账户："+usernameText);
            Log.e(TAG,"密码："+passwordText);
            Log.e(TAG,"性别："+sexText);
            //对账号和密码进行检测
            if(TextUtils.isEmpty(usernameText)){
                //账号为空
                Toast.makeText(this,"用户名不可以为空",Toast.LENGTH_SHORT).show();
                return;
            }else if(TextUtils.isEmpty(passwordText)){
                //密码为空
                Toast.makeText(this,"密码不可以为空",Toast.LENGTH_SHORT).show();
            }else {
                boolean result = mIUserDao.isExist(usernameText);
                if (result) {
                    //用户名已被使用
                    Toast.makeText(this, "此用户名已被注册", Toast.LENGTH_SHORT).show();
                } else {
                    user = new User(usernameText, passwordText, sexText);
                    int rs = (int) mIUserDao.Register(user);
                    Log.e(TAG,"rs："+rs);
                    if (rs > -1) {
                        //注册成功，跳回登录页面
                        Intent intent = new Intent();
                        setResult(2, intent);
                        finish();
                    }
                }
            }
        }

        private void initView() {
            mUsername = (EditText)this.findViewById(R.id.r_username);
            mPassword = (EditText)this.findViewById(R.id.r_password);
            mSex = (RadioGroup)this.findViewById(R.id.radioGroup);
            mRegisterBtn =(Button)this.findViewById(R.id.register_btn);
            mIUserDao =new UserDaoImpl(this);
            mR=(RadioButton)this.findViewById(R.id.man_radio);
        }



}

IndexActivity.java

package com.example.familybook;

import android.app.Activity;
import android.os.Bundle;

import androidx.annotation.Nullable;

public class IndexActivity extends Activity {
    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_index);
    }
}

database

UserDatabaseHelper.java

package com.example.familybook.database;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;


import androidx.annotation.Nullable;

import com.example.familybook.utils.Constants;


public class UserDatabaseHelper extends SQLiteOpenHelper {
    private static final String TAG = "UserDatabaseHelper";

    public UserDatabaseHelper(@Nullable Context context) {
        super(context, Constants.USER_DB_NAME,null,Constants.USER_DB_VERSION);
    }


    @Override
    public void onCreate(SQLiteDatabase db) {
        /**
         * 创建数据库
         */
        Log.e(TAG,"数据库创建.....");
        String createsql=" create table  " +Constants.USER_TABLE_NAME +"("+Constants.USER_TABLE_FIELD_ID + " integer primary key autoincrement," +Constants.USER_TABLE_FIELD_UNAME +" varchar(30)," +Constants.USER_TABLE_FIELD_UPWD+ " varchar(32)," +Constants.USER_TABLE_FIELD_SEX +" varchar(5)  )";
        db.execSQL(createsql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        /**
         * 数据库更新
         */
    }
}

 entity

User.java

package com.example.familybook.entity;

/**
 * 用户账号实体类
 */
public class User {
    private int _id;
    private String username;
    private String password;
    private String sex;

    public User( ) {

    }

    public User( String username, String password, String sex) {
        this.username = username;
        this.password = password;
        this.sex = sex;
    }


    public User(int id, String username, String password, String sex) {
        _id = id;
        this.username = username;
        this.password = password;
        this.sex = sex;
    }


    public int get_id() {
        return _id;
    }

    public void set_id(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 String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "User{" +
                "_id=" + _id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", sex='" + sex + '\'' +
                '}';
    }
}

utils

Constants.java

package com.example.familybook.utils;
/**
 * 常量类
 */
public class Constants {

    public static final String USER_DB_NAME="user.db";
    public static final int USER_DB_VERSION=1;
    public static final String USER_TABLE_NAME="user";
    public static final String USER_TABLE_FIELD_ID="_id";
    public static final String USER_TABLE_FIELD_UNAME="username";
    public static final String USER_TABLE_FIELD_UPWD="password";
    public static final String USER_TABLE_FIELD_SEX="sex";

}

dao

IUserDao.java

package com.example.familybook.dao;

import com.example.familybook.entity.User;

/**
 * 这是User数据库接口层
 */
public interface IUserDao {
    boolean isExist(String username);
    boolean Login(String username,String password);
    long Register(User user);
    User  Query(String username,String password);
    User Query(String username);
}

UserDaoImpl.java

package com.example.familybook.dao;

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

import com.example.familybook.database.UserDatabaseHelper;
import com.example.familybook.entity.User;
import com.example.familybook.utils.Constants;

public class UserDaoImpl implements IUserDao {
    private  final UserDatabaseHelper mUserDatabaseHelper;

    public UserDaoImpl(Context context){
        mUserDatabaseHelper=new UserDatabaseHelper(context);
    }



    @Override
    public boolean isExist(String username) {

        return Query(username)==null? false:true;
    }

    /**
     * 该方法用于登录
     * @param username
     * @param password
     * @return
     */
    @Override
    public boolean Login(String username,String password) {
        return Query(username,password)==null? false:true;
    }

    /**
     * 该方法用于注册账户
     * @param user
     * @return
     */
    @Override
    public long Register(User user) {
        SQLiteDatabase db =mUserDatabaseHelper.getWritableDatabase();
        long result =-1;
//        db.beginTransaction();
        try {
            ContentValues values  =new ContentValues();
            values.put(Constants.USER_TABLE_FIELD_UNAME,user.getUsername());
            values.put(Constants.USER_TABLE_FIELD_UPWD,user.getPassword());
            values.put(Constants.USER_TABLE_FIELD_SEX,user.getSex());
            result=db.insert(Constants.USER_TABLE_NAME,null,values);
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            db.close();
//            db.endTransaction();
        }

        return result;
    }

    /**
     * 该方法是通过检查用户名和密码查询用户
     * @param username
     * @param password
     * @return
     */
    @Override
    public User Query(String username, String password) {
        User user= null;
        SQLiteDatabase db =mUserDatabaseHelper.getWritableDatabase();

            /**
             * 如果数据库不为空，进行查询
             */

//            db.beginTransaction();
            try {

                String sql = "select * from " + Constants.USER_TABLE_NAME + " where " + Constants.USER_TABLE_FIELD_UNAME + "=? and " + Constants.USER_TABLE_FIELD_UPWD + "=?";
                String[] str = new String[]{username, password};
                Cursor cursor = db.rawQuery(sql, str);
                /**
                 * 下面在库中进行具体查询,并将
                 */
                if (cursor.moveToNext()) {
                    /**
                     * 将查到的数据逐一封装到user对象中
                     */

                    user = new User();
                    //set id
                    int userID = cursor.getInt(cursor.getColumnIndex(Constants.USER_TABLE_FIELD_ID));
                    user.set_id(userID);
                    //set username
                    String uname = cursor.getString(cursor.getColumnIndex(Constants.USER_TABLE_FIELD_UNAME));
                    user.setUsername(uname);
                    //set password
                    String upwd = cursor.getString(cursor.getColumnIndex(Constants.USER_TABLE_FIELD_UPWD));
                    user.setPassword(upwd);
                    //set sex
                    String usex = cursor.getString(cursor.getColumnIndex(Constants.USER_TABLE_FIELD_SEX));
                    user.setSex(usex);
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                db.close();
//                db.endTransaction();
            }

        return user;
    }

    /**
     * 该方法是通过检查用户名来查找用户
     * @param username
     * @return
     */
    @Override
    public User Query(String username) {
        User user= null;
        SQLiteDatabase db =mUserDatabaseHelper.getWritableDatabase();
//        db.beginTransaction();
        try {

            String sql ="select * from "+Constants.USER_TABLE_NAME+" where "+Constants.USER_TABLE_FIELD_UNAME+"=? ";
            String[] str  =new  String[]{username};
            Cursor cursor =db.rawQuery(sql,str);
            /**
             * 下面在库中进行具体查询,并将
             */
            if(cursor.moveToNext()){
                /**
                 * 将查到的数据逐一封装到user对象中
                 */

                user  =new User();
                //set id
                int userID = cursor.getInt(cursor.getColumnIndex(Constants.USER_TABLE_FIELD_ID));
                user.set_id(userID);
                //set username
                String uname=cursor.getString(cursor.getColumnIndex(Constants.USER_TABLE_FIELD_UNAME));
                user.setUsername(uname);
                //set password
                String upwd=cursor.getString(cursor.getColumnIndex(Constants.USER_TABLE_FIELD_UPWD));
                user.setPassword(upwd);
                //set sex
                String usex=cursor.getString(cursor.getColumnIndex(Constants.USER_TABLE_FIELD_SEX));
                user.setSex(usex);
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            db.close();
//            db.endTransaction();
        }

        return user;
    }
}

layout

activity_login.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout

    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@mipmap/login">


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="50dp"
        android:padding="30dp"
        android:orientation="vertical">

        <TextView
            android:layout_width="wrap_content"
            android:layout_marginLeft="30dp"
            android:drawableLeft="@mipmap/ic_launcher_round"
            android:text="家庭记账本"
            android:textSize="40sp"
            android:layout_height="wrap_content"/>

        <EditText
            android:id="@+id/username"
            android:layout_width="match_parent"
            android:layout_marginTop="30dp"
            android:maxLines="1"
            android:layout_height="wrap_content"
            android:hint="用户名" />
        <EditText
            android:id="@+id/password"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:inputType="textPassword"
            android:maxLines="1"
            android:hint="密码" />
        <Button
            android:id="@+id/login_btn"
            android:layout_width="match_parent"
            android:text="登录"
            android:textSize="20sp"
            android:layout_height="wrap_content"/>

        <Button
            android:id="@+id/goto_register_btn"
            android:background="@android:color/transparent"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:layout_gravity="center"
            android:text="没有账号,立即去注册"
            android:textColor="#00ffff"
            android:textSize="16sp" />



    </LinearLayout>



</LinearLayout>

activity_register.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:background="@mipmap/register"
    android:padding="30dp"
    android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:text="欢迎注册家庭记账本"
        android:textSize="30sp"
        android:layout_marginTop="30dp"
        android:layout_gravity="center"
        android:layout_height="wrap_content"/>
    <EditText
        android:id="@+id/r_username"
        android:layout_width="match_parent"
        android:layout_marginTop="30dp"
        android:hint="请输入用户名"
        android:layout_height="wrap_content"/>
    <EditText
        android:id="@+id/r_password"
        android:layout_width="match_parent"
        android:layout_marginTop="30dp"
        android:inputType="text"
        android:hint="请输入密码"
        android:layout_height="wrap_content"/>
    <RadioGroup
        android:id="@+id/radioGroup"
        android:layout_width="wrap_content"
        android:layout_gravity="center"
        android:orientation="horizontal"
        android:layout_height="wrap_content">
        <RadioButton
            android:id="@+id/man_radio"
            android:layout_width="wrap_content"
            android:text="男"
            android:checked="true"
            android:layout_height="wrap_content">

        </RadioButton>
        <RadioButton
            android:id="@+id/woman_group"
            android:layout_width="wrap_content"
            android:text="女"
            android:layout_height="wrap_content">

        </RadioButton>
    </RadioGroup>
    <Button
        android:id="@+id/register_btn"
        android:layout_width="wrap_content"
        android:text="注册"
        android:layout_gravity="center"
        android:layout_height="wrap_content"/>
</LinearLayout>

activity_index.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:text="首页"
        android:textSize="50sp"
        android:layout_gravity="center"
        android:layout_height="wrap_content"/>
    <TextView
        android:layout_width="wrap_content"
        android:text="登录成功"
        android:layout_marginTop="200dp"
        android:layout_gravity="center"
        android:textSize="40sp"
        android:layout_height="wrap_content"/>
</LinearLayout>