使用GreenDao建立表、關聯表（一對一，一對多，多對多）、CURD、升級資料庫等操作
阿新 • • 發佈：2018-10-31
應用場景：從照片中找出包含有使用者人臉的照片，並儲存該照片中的人臉特徵、使用該特徵和使用者人臉特徵對比，滿足條件，照片就儲存到該使用者表裡
一、建立表
GreenDao託管地址：https://github.com/greenrobot/greenDAO
官方文件：http://greenrobot.org/greendao/documentation/updating-to-greendao-3-and-annotations
新增GreenDao外掛到專案中
classpath 'org.greenrobot:greendao-gradle-plugin:3.2.2'
buildscript {
repositories {
..............................................................
}
dependencies {
.............................................................
classpath 'org.greenrobot:greendao-gradle-plugin:3.2.2'
}
}新增依賴到模組中
apply plugin: 'org.greenrobot.greendao' // apply plugin dependencies { ............ implementation 'org.greenrobot:greendao:3.2.2' // add library }
實體類
@Entity public class PortraitPhoto { @Id(autoincrement = true) //id引數型別要使用Long,不然儲存後id一直為0 private Long id; private String name; private String path; private int faceCount; private String sdCardId; //一對多的關係,一張照片可能有多個人,所以會有多個人臉特徵(一張臉一個特徵) @ToMany(referencedJoinProperty = "portraitPhotoId") List<Feature> featureList; }
@Entity
public class Feature {
@Id(autoincrement = true)
private Long id;
private Long portraitPhotoId;
private byte[] features;
}用於儲存使用者id ,因為使用者id是唯一的,所以我用它來做UserPhoto表的主鍵,也就是userId,下面儲存多對多關係時會用到
@Entity public class UserPhoto {
@Id private Long id;
//照片和使用者是多對多的關係
@ToMany
@JoinEntity(entity = PhotoJoinUser.class, sourceProperty = "userId", targetProperty = "portraitPhotoId")
private List<PortraitPhoto> portraitphotoList;多對多的關係,需要建立中間表,一張照片裡面可能有多個使用者,一個使用者可以出現多張照片裡面
@Entity
public class PhotoJoinUser {
@Id
private Long id;
private Long portraitPhotoId;
private Long userId;
}
實體類建立好之後,點選AndroidStudio工具欄 Build - Make project
初始化
//UpgradeHelper 是升級資料庫相關的一個類,繼承DaoMaster.OpenHelper
UpgradeHelper openHelper = new UpgradeHelper(context, NAME,null);
final Database db = openHelper.getWritableDb();
mDaoSession = new DaoMaster(db).newSession();
執行一下,就能建立表了,如下圖(這是新增資料後,可以看看錶的結構)
二、儲存
mPortraitPhotoDao = mDaoSession.getPortraitPhotoDao();
mFeatureDao = mDaoSession.getFeatureDao();
for (PortraitPhoto portraitPhoto : portraitPhotoList) {
......................
if (portraitPhoto.getFaceCount() == NOBODY) {
continue;
}
Bitmap bitmap = BitmapFactory.decodeFile(portraitPhoto.getPath());
if (mPrtekIIS == null || bitmap == null) {
continue;
}
final int width = bitmap.getWidth() & ~1;
final int height = bitmap.getHeight() & ~1;
Image image = new AshmemImage(ImageFormat.NV21, width, height);
image.setBitmap(bitmap, new Rect(0, 0, width, height));
//查詢圖片中是否有人
List<Person> persons = mPrtekIIS.findPersons(image);
if (persons == null || persons.isEmpty()) {
portraitPhoto.setFaceCount(NOBODY);
//儲存沒有人臉的照片
mPortraitPhotoDao.insert(portraitPhoto);
continue;
}
portraitPhoto.setFaceCount(persons.size());
//儲存有人臉的照片
mPortraitPhotoDao.insert(portraitPhoto);
//儲存特徵
for (Person person : persons) {
FaceFeature facefeature = person.getFace().getFeature();
if (facefeature == null) {
continue;
}
Feature feature = new Feature();
feature.setFeatures(facefeature.serialize());
//一對多關係儲存方式
feature.setPortraitPhotoId(portraitPhoto.getId());
mFeatureDao.insert(feature);
}
portraitPhotos.add(portraitPhoto);
}多對多關係儲存
//照片和使用者已經儲存過了,所以只要在第三張繫結一下Id就可以了
PhotoJoinUser photoJoinUser = new PhotoJoinUser();
//照片的id
photoJoinUser.setPortraitPhotoId(portraitPhoto.getId());
//使用者的id
photoJoinUser.setUserId(user.getUserId());
//儲存
mDaoSession.insert(photoJoinUser);GreenDao CURD方法支援多種引數型別
insertInTx()//儲存 集合或陣列、可變引數
insertOrReplace()//如果資料庫中不存在這一條資訊就儲存,否則替換三、更新
update()//更新很簡單,專案也沒有使用,所以就不舉例子說明了四、刪除
GreenDao不支援刪除級聯，有關聯表的資料需要查詢後再逐一刪除，例如，刪除了一張照片，照片裡有使用者（包含特徵）。但是關聯特徵表裡的資料不會刪掉
public void deletePhoto(List<PortraitPhoto> photos) {
if (photos == null || photos.isEmpty()) {
return;
}
final PhotoJoinUserDao photoJoinUserDao = mDaoSession.getPhotoJoinUserDao();
final FeatureDao featureDao = mDaoSession.getFeatureDao();
final PortraitPhotoDao portraitPhotoDao = mDaoSession.getPortraitPhotoDao();
for (PortraitPhoto photo : photos) {
//通過條件(照片id)從中間表刪除
photoJoinUserDao.queryBuilder()
.where(PhotoJoinUserDao.Properties.PortraitPhotoId.eq(photo.getId()))
.buildDelete()
.executeDeleteWithoutDetachingEntities();
//獲取該照片所有特徵
final List<Feature> featureList = photo.getFeatureList();
if (featureList != null) {
//刪除
featureDao.deleteInTx(featureList);
}
}
//最後刪除該照片集合(其實裡邊就一張,只是通過條件查詢時返回List<PortraitPhoto>)
portraitPhotoDao.deleteInTx(photos);
}五、查詢
final List<PortraitPhoto> dbPhotoList = mPortraitPhotoDao.queryBuilder()
.where(PortraitPhotoDao.Properties.SdCardId.eq(mSdcardId))
.list();六、升級
//在模組的Build.grade檔案新增、
greendao{
schemaVersion 2//修改版本號,即可升級
}GreenDao資料庫升級預設是不會遷移資料的，之前的資料將會丟失。下面是在stackoverflow網站找到了解決方案，也寫了相關的作者和編輯人員
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.annotation.NonNull;
import android.text.TextUtils;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.greenrobot.greendao.AbstractDao;
import org.greenrobot.greendao.database.Database;
import org.greenrobot.greendao.database.StandardDatabase;
import org.greenrobot.greendao.internal.DaoConfig;
/**
* Createdby PedroOkawa and modified by MBH on 16/08/16.
*/
public final class MigrationHelper {
public static void migrate(SQLiteDatabase sqliteDatabase, Class<? extends AbstractDao<?, ?>>... daoClasses) {
StandardDatabase db = new StandardDatabase(sqliteDatabase);
generateNewTablesIfNotExists(db, daoClasses);
generateTempTables(db, daoClasses);
dropAllTables(db, true, daoClasses);
createAllTables(db, false, daoClasses);
restoreData(db, daoClasses);
}
public static void migrate(StandardDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
generateNewTablesIfNotExists(db, daoClasses);
generateTempTables(db, daoClasses);
dropAllTables(db, true, daoClasses);
createAllTables(db, false, daoClasses);
restoreData(db, daoClasses);
}
private static void generateNewTablesIfNotExists(StandardDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
reflectMethod(db, "createTable", true, daoClasses);
}
private static void generateTempTables(StandardDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
for (int i = 0; i < daoClasses.length; i++) {
DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);
String tableName = daoConfig.tablename;
String tempTableName = daoConfig.tablename.concat("_TEMP");
StringBuilder insertTableStringBuilder = new StringBuilder();
insertTableStringBuilder.append("CREATE TEMP TABLE ").append(tempTableName);
insertTableStringBuilder.append(" AS SELECT * FROM ").append(tableName).append(";");
db.execSQL(insertTableStringBuilder.toString());
}
}
private static void dropAllTables(StandardDatabase db, boolean ifExists, @NonNull Class<? extends AbstractDao<?, ?>>... daoClasses) {
reflectMethod(db, "dropTable", ifExists, daoClasses);
}
private static void createAllTables(StandardDatabase db, boolean ifNotExists, @NonNull Class<? extends AbstractDao<?, ?>>... daoClasses) {
reflectMethod(db, "createTable", ifNotExists, daoClasses);
}
/**
* dao class already define the sql exec method, so just invoke it
*/
private static void reflectMethod(StandardDatabase db, String methodName, boolean isExists, @NonNull Class<? extends AbstractDao<?, ?>>... daoClasses) {
if (daoClasses.length < 1) {
return;
}
try {
for (Class cls : daoClasses) {
Method method = cls.getDeclaredMethod(methodName, Database.class, boolean.class);
method.invoke(null, db, isExists);
}
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
private static void restoreData(StandardDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
for (int i = 0; i < daoClasses.length; i++) {
DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);
String tableName = daoConfig.tablename;
String tempTableName = daoConfig.tablename.concat("_TEMP");
// get all columns from tempTable, take careful to use the columns list
List<String> columns = getColumns(db, tempTableName);
ArrayList<String> properties = new ArrayList<>(columns.size());
for (int j = 0; j < daoConfig.properties.length; j++) {
String columnName = daoConfig.properties[j].columnName;
if (columns.contains(columnName)) {
properties.add(columnName);
}
}
if (properties.size() > 0) {
final String columnSQL = TextUtils.join(",", properties);
StringBuilder insertTableStringBuilder = new StringBuilder();
insertTableStringBuilder.append("INSERT INTO ").append(tableName).append(" (");
insertTableStringBuilder.append(columnSQL);
insertTableStringBuilder.append(") SELECT ");
insertTableStringBuilder.append(columnSQL);
insertTableStringBuilder.append(" FROM ").append(tempTableName).append(";");
db.execSQL(insertTableStringBuilder.toString());
}
StringBuilder dropTableStringBuilder = new StringBuilder();
dropTableStringBuilder.append("DROP TABLE ").append(tempTableName);
db.execSQL(dropTableStringBuilder.toString());
}
}
private static List<String> getColumns(StandardDatabase db, String tableName) {
List<String> columns = null;
Cursor cursor = null;
try {
cursor = db.rawQuery("SELECT * FROM " + tableName + " limit 0", null);
if (null != cursor && cursor.getColumnCount() > 0) {
columns = Arrays.asList(cursor.getColumnNames());
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (cursor != null)
cursor.close();
if (null == columns)
columns = new ArrayList<>();
}
return columns;
}
}前面初始化時，用到的 UpgradeHelper 類，在onUpgrade方法更新
public class UpgradeHelper extends DaoMaster.OpenHelper {
public UpgradeHelper(Context context, String name, SQLiteDatabase.CursorFactory factory) {
super(context, name, factory);
}
@Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
MigrationHelper.migrate(db, PortraitPhotoDao.class, FeatureDao.class, PhotoJoinUserDao.class,
UserPhotoDao.class);
}
}