【Android】家庭记账本手机版开发报告二
2024-09-07 04:24:44
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("\n");
}
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("\n");
}
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;
} }
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