【Android】家庭记账本手机版开发报告二

一、说在前面

昨天	完成了对记账本的账单的增删
今天	完善昨天的框架结构（ 1、引入ViewModel管理数据、使MainActive 只管理界面、不再管数据了 2、引入AsyncTask、后台执行。不必强制在主线程执行 3、将Database.java修改为singleton模式、只维护一个Database 4、引入LiveData ）
问题	没有

二、结构完善

1、引入LiveData，管理所有账单，设置观察者，自主更新界面数据，不必再调用unDataView（）来更新界面。

1)、Dao

@Query("SELECT * From ACCOUNTRECORD ORDER BY ID DESC")
    LiveData<List<AccountRecord>> getAllAccountRecordLive ();

2）、在MainActive中设置观察者

 accountRecordViewModel.getAllAcountRecord().observe(this, new Observer<List<AccountRecord>>() {
            @Override
            public void onChanged(List<AccountRecord> accountRecords) {
                StringBuilder text = new StringBuilder();
                for (int i=0;i<accountRecords.size();i++){
                    AccountRecord accountRecord = accountRecords.get(i);
                    text.append(accountRecord.getId()).append("   ").append(accountRecord.getCostType()).append("   ").append(accountRecord.getCostTime()).append("   ").append(accountRecord.getCostMoney()).append("
");
                }
                textView.setText(text.toString());
            }
        });

2、引入ViewModel管理数据、使MainActive 只管理界面、不再管数据了

1）、仓库类操作数据库

package com.me.familybookkeepingbook;

import android.content.Context;
import android.os.AsyncTask;

import androidx.lifecycle.LiveData;

import java.util.List;

public class AccountRecordRepository {
    private LiveData<List<AccountRecord>> allAcountRecord;
    private AccountRecordDao accountRecordDao;
    public AccountRecordRepository(Context context) {
        AccountRecordDatabase accountRecordDatabase = AccountRecordDatabase.getAccountRecordDataBase(context.getApplicationContext());
        accountRecordDao = accountRecordDatabase.getAccountRecordDao();
        allAcountRecord = accountRecordDao.getAllAccountRecordLive();
    }

    public LiveData<List<AccountRecord>> getAllAcountRecord() {
        return allAcountRecord;
    }
    void insertAccountRecord(AccountRecord ... accountRecords){
        new InsertAsyncTask(accountRecordDao).execute(accountRecords);
    }
    void deleteAllAccountRecord(){
        new DeleteAsyncTask(accountRecordDao).execute();
    }
    static class InsertAsyncTask extends AsyncTask<AccountRecord ,Void,Void> {
        private AccountRecordDao accountRecordDao;

        public InsertAsyncTask(AccountRecordDao accountRecordDao) {
            this.accountRecordDao = accountRecordDao;
        }

        @Override
        protected Void doInBackground(AccountRecord... accountRecords) {
            accountRecordDao.insertAccountRecord(accountRecords);
            return null;
        }
    }
    static class DeleteAsyncTask extends AsyncTask<Void ,Void,Void>{
        private AccountRecordDao accountRecordDao;

        public DeleteAsyncTask(AccountRecordDao accountRecordDao) {
            this.accountRecordDao = accountRecordDao;
        }

        @Override
        protected Void doInBackground(Void... Voids) {
            accountRecordDao.deleteAllAccountRecord();
            return null;
        }
    }
}

2）、ViewModel管理数据

package com.me.familybookkeepingbook;

import android.app.Application;
import android.os.AsyncTask;

import androidx.annotation.NonNull;
import androidx.lifecycle.AndroidViewModel;
import androidx.lifecycle.LiveData;

import java.util.List;

public class AccountRecordViewModel extends AndroidViewModel {
    private AccountRecordRepository accountRecordRepository;
    public AccountRecordViewModel(@NonNull Application application) {
        super(application);
        accountRecordRepository = new AccountRecordRepository(application);
    }

    public LiveData<List<AccountRecord>> getAllAcountRecord() {
        return accountRecordRepository.getAllAcountRecord();
    }

    void insertAccountRecord(AccountRecord ... accountRecords){
        accountRecordRepository.insertAccountRecord(accountRecords);
    }
    void deleteAllAccountRecord(){
        accountRecordRepository.deleteAllAccountRecord();
    }
    static class InsertAsyncTask extends AsyncTask<AccountRecord ,Void,Void> {
        private AccountRecordDao accountRecordDao;

        public InsertAsyncTask(AccountRecordDao accountRecordDao) {
            this.accountRecordDao = accountRecordDao;
        }

        @Override
        protected Void doInBackground(AccountRecord... accountRecords) {
            accountRecordDao.insertAccountRecord(accountRecords);
            return null;
        }
    }
    static class DeleteAsyncTask extends AsyncTask<Void ,Void,Void>{
        private AccountRecordDao accountRecordDao;

        public DeleteAsyncTask(AccountRecordDao accountRecordDao) {
            this.accountRecordDao = accountRecordDao;
        }

        @Override
        protected Void doInBackground(Void... Voids) {
            accountRecordDao.deleteAllAccountRecord();
            return null;
        }
    }
}

3）、MainActive 管理界面

package com.me.familybookkeepingbook;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;
import androidx.lifecycle.Observer;
import androidx.lifecycle.ViewModelProviders;

import java.util.List;

public class MainActivity extends AppCompatActivity {
    AccountRecordViewModel accountRecordViewModel;
    Button buttonInsert,buttonDelete;
    TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        accountRecordViewModel = ViewModelProviders.of(this).get(AccountRecordViewModel.class);
        textView = findViewById(R.id.textView);
        buttonDelete = findViewById(R.id.buttonDelete);
        buttonInsert = findViewById(R.id.buttonInsert);
        accountRecordViewModel.getAllAcountRecord().observe(this, new Observer<List<AccountRecord>>() {
            @Override
            public void onChanged(List<AccountRecord> accountRecords) {
                StringBuilder text = new StringBuilder();
                for (int i=0;i<accountRecords.size();i++){
                    AccountRecord accountRecord = accountRecords.get(i);
                    text.append(accountRecord.getId()).append("   ").append(accountRecord.getCostType()).append("   ").append(accountRecord.getCostTime()).append("   ").append(accountRecord.getCostMoney()).append("
");
                }
                textView.setText(text.toString());
            }
        });
        buttonInsert.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                AccountRecord accountRecord = new AccountRecord(1,"2020-01-26","学习",100.0);
                accountRecordViewModel.insertAccountRecord(accountRecord);
            }
        });
        buttonDelete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                accountRecordViewModel.deleteAllAccountRecord();
            }
        });
    }


}

3、引入AsyncTask、后台执行。不必强制在主线程执行

static class InsertAsyncTask extends AsyncTask<AccountRecord ,Void,Void> {
        private AccountRecordDao accountRecordDao;

        public InsertAsyncTask(AccountRecordDao accountRecordDao) {
            this.accountRecordDao = accountRecordDao;
        }

        @Override
        protected Void doInBackground(AccountRecord... accountRecords) {
            accountRecordDao.insertAccountRecord(accountRecords);
            return null;
        }
    }
    static class DeleteAsyncTask extends AsyncTask<Void ,Void,Void>{
        private AccountRecordDao accountRecordDao;

        public DeleteAsyncTask(AccountRecordDao accountRecordDao) {
            this.accountRecordDao = accountRecordDao;
        }

        @Override
        protected Void doInBackground(Void... Voids) {
            accountRecordDao.deleteAllAccountRecord();
            return null;
        }
    }

4、将Database.java修改为singleton模式、只维护一个Database

package com.me.familybookkeepingbook;

import android.content.Context;

import androidx.room.Database;
import androidx.room.Room;
import androidx.room.RoomDatabase;
@Database(entities = {AccountRecord.class },version = 1,exportSchema = false)
public abstract class AccountRecordDatabase extends RoomDatabase {
    private static AccountRecordDatabase INSTANCE;
    public abstract AccountRecordDao getAccountRecordDao();
    static synchronized AccountRecordDatabase getAccountRecordDataBase(Context context){
        if (INSTANCE == null){
            INSTANCE = Room.databaseBuilder(context.getApplicationContext(),AccountRecordDatabase.class,"accountrecord_database")
                    .build();
        }
        return INSTANCE;
    }

}