GreenDao3.0+的基本使用，数据库升级

GreenDao 是一个使用便捷的数据库框架，下面是如何调用，实现数据库升级功能，话不多说，直接上代码。

1. 在app下的build.gradle中添加依赖：

compile 'org.greenrobot:greendao:3.1.0'
compile 'org.greenrobot:greendao-generator:3.1.0'

2.添加基本数据库标识：

greendao {
    schemaVersion 3  //版本
    daoPackage 'guo.greendaodemo.entity.dao' // 一般为app包名+生成文件的文件夹名
    targetGenDir 'src/main/java' //生成文件路径
}

3. 在项目的build.gradle中添加：

repositories {
    google()
    jcenter()
    mavenCentral()
}
dependencies {
    classpath 'com.android.tools.build:gradle:3.0.1'
    classpath 'org.greenrobot:greendao-gradle-plugin:3.1.0'
    
}

4.在项目中新建一个实体类（Entity 表示为一个实体类，让GreenDao能够识别，ID为唯一的自增的id标识），然后点击Build下的Make Project 会自动生成实体类dao.

@Entity
public class UserEntity {
    @Id
    private long id;
    private String name;
    private String age;
    @Generated(hash = 1132182872)
    public UserEntity(long id, String name, String age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }
    @Generated(hash = 1433178141)
    public UserEntity() {
    }
    public String getName() {
        return this.name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public long getId() {
        return this.id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getAge() {
        return this.age;
    }
    public void setAge(String age) {
        this.age = age;
    }
}

5. 初始化类封装：

public class DbManager {

    // 是否加密
    public static final boolean ENCRYPTED = true;
    public static final String path = Environment.getExternalStorageDirectory() + File.separator
            + "GreenDaoDemo" + File.separator
            + "db" + File.separator;
  //  private static final String DB_NAME = "test.db";
    private static DbManager mDbManager;
    private static MyOpenHelper mDevOpenHelper;
    private static DaoMaster mDaoMaster;
    private static DaoSession mDaoSession;

    private Context mContext;

    private DbManager(Context context) {
        this.mContext = context;
        // 初始化数据库信息
        File file =new File(path);
        mDevOpenHelper = new MyOpenHelper(context,file.getAbsolutePath()+"test.db",null);
        getDaoMaster(context);
        getDaoSession(context);
    }

    public static DbManager getInstance(Context context) {
        if (null == mDbManager) {
            synchronized (DbManager.class) {
                if (null == mDbManager) {
                    mDbManager = new DbManager(context);
                }
            }
        }
        return mDbManager;
    }

    /**
     * 获取可读数据库
     *
     * @param context
     * @return
     */
    public static SQLiteDatabase getReadableDatabase(Context context) {
        if (null == mDevOpenHelper) {
            getInstance(context);
        }
        return mDevOpenHelper.getReadableDatabase();
    }

    /**
     * 获取可写数据库
     *
     * @param context
     * @return
     */
    public static SQLiteDatabase getWritableDatabase(Context context) {
        if (null == mDevOpenHelper) {
            getInstance(context);
        }
        return mDevOpenHelper.getWritableDatabase();
    }

    /**
     * 获取DaoMaster
     *
     * 判断是否存在数据库，如果没有则创建数据库
     * @param context
     * @return
     */
    public static DaoMaster getDaoMaster(Context context) {
        if (null == mDaoMaster) {
            synchronized (DbManager.class) {
                if (null == mDaoMaster) {
                    MyOpenHelper helper = new MyOpenHelper(context,path+"test.db",null);
                    mDaoMaster = new DaoMaster(helper.getWritableDatabase());
                }
            }
        }
        return mDaoMaster;
    }

    /**
     * 获取DaoSession
     *
     * @param context
     * @return
     */
    public static DaoSession getDaoSession(Context context) {
        if (null == mDaoSession) {
            synchronized (DbManager.class) {
                mDaoSession = getDaoMaster(context).newSession();
            }
        }

        return mDaoSession;
    }
}

6.MyOpenHelper 类：

public class MyOpenHelper extends DaoMaster.OpenHelper {

    public MyOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory) {
        super(context, name, factory);
    }


    /**
     * 数据库升级
     * @param db
     * @param oldVersion
     * @param newVersion
     */
    @Override
    public void onUpgrade(Database db, int oldVersion, int newVersion) {
        //操作数据库的更新 有几个表升级都可以传入到下面
        // MigrationHelper.getInstance().migrate(db,StudentDao.class,XXXDao.class);
         MigrationHelper.getInstance().migrate(db,UserEntityDao.class);
    }
}

7.MigrationHelper (数据库升级帮助类，解决int,long,byte类型出现 not null)

 * 流程 ：
 * 1.创建临时表
 * 2.删除所有表
 * 3.创建新的表
 * 4.向表中写数据
 */

public final class MigrationHelper {

    private static final String CONVERSION_CLASS_NOT_FOUND_EXCEPTION = "MIGRATION HELPER - CLASS DOESN’T MATCH WITH THE CURRENT PARAMETERS";
    public static boolean DEBUG = false;
    private static String TAG = "MigrationHelper";
    private static final String SQLITE_MASTER = "sqlite_master";
    private static final String SQLITE_TEMP_MASTER = "sqlite_temp_master";

    private static MigrationHelper instance;

    public static MigrationHelper getInstance() {
        if (instance == null) {
            instance = new MigrationHelper();
        }
        return instance;
    }


    private static WeakReference<ReCreateAllTableListener> weakListener;

    public interface ReCreateAllTableListener {
        void onCreateAllTables(Database db, boolean ifNotExists);

        void onDropAllTables(Database db, boolean ifExists);
    }

    public static void migrate(SQLiteDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        printLog("【The Old Database Version】" + db.getVersion());
        Database database = new StandardDatabase(db);
        migrate(database, daoClasses);
    }

    public static void migrate(SQLiteDatabase db, ReCreateAllTableListener listener, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        weakListener = new WeakReference<>(listener);
        migrate(db, daoClasses);
    }

    public static void migrate(Database database, ReCreateAllTableListener listener, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        weakListener = new WeakReference<>(listener);
        migrate(database, daoClasses);
    }

    public static void migrate(Database database, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        printLog("【Generate temp table】start");
        generateTempTables(database, daoClasses);
        printLog("【Generate temp table】complete");

        ReCreateAllTableListener listener = null;
        if (weakListener != null) {
            listener = weakListener.get();
        }

        if (listener != null) {
            listener.onDropAllTables(database, true);
            printLog("【Drop all table by listener】");
            listener.onCreateAllTables(database, false);
            printLog("【Create all table by listener】");
        } else {
            dropAllTables(database, true, daoClasses);
            createAllTables(database, false, daoClasses);
        }
        printLog("【Restore data】start");
        restoreData(database, daoClasses);
        printLog("【Restore data】complete");
    }

    /**
     * 生成临时列表
     *
     * @param db
     * @param daoClasses
     */
    private static void generateTempTables(Database db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        for (int i = 0; i < daoClasses.length; i++) {
            String tempTableName = null;

            DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);
            String tableName = daoConfig.tablename;
            if (!isTableExists(db, false, tableName)) {
                printLog("【New Table】" + tableName);
                continue;
            }
            try {
                tempTableName = daoConfig.tablename.concat("_TEMP");
                StringBuilder dropTableStringBuilder = new StringBuilder();
                dropTableStringBuilder.append("DROP TABLE IF EXISTS ").append(tempTableName).append(";");
                db.execSQL(dropTableStringBuilder.toString());

                StringBuilder insertTableStringBuilder = new StringBuilder();
                insertTableStringBuilder.append("CREATE TEMPORARY TABLE ").append(tempTableName);
                insertTableStringBuilder.append(" AS SELECT * FROM ").append(tableName).append(";");
                db.execSQL(insertTableStringBuilder.toString());
                printLog("【Table】" + tableName + "\n ---Columns-->" + getColumnsStr(daoConfig));
                printLog("【Generate temp table】" + tempTableName);
            } catch (SQLException e) {
                Log.e(TAG, "【Failed to generate temp table】" + tempTableName, e);
            }
        }
    }

    private static boolean isTableExists(Database db, boolean isTemp, String tableName) {
        if (db == null || TextUtils.isEmpty(tableName)) {
            return false;
        }
        String dbName = isTemp ? SQLITE_TEMP_MASTER : SQLITE_MASTER;
        String sql = "SELECT COUNT(*) FROM " + dbName + " WHERE type = ? AND name = ?";
        Cursor cursor = null;
        int count = 0;
        try {
            cursor = db.rawQuery(sql, new String[]{"table", tableName});
            if (cursor == null || !cursor.moveToFirst()) {
                return false;
            }
            count = cursor.getInt(0);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (cursor != null) {
                cursor.close();
            }
        }
        return count > 0;
    }


    private static String getColumnsStr(DaoConfig daoConfig) {
        if (daoConfig == null) {
            return "no columns";
        }
        StringBuilder builder = new StringBuilder();
        for (int i = 0; i < daoConfig.allColumns.length; i++) {
            builder.append(daoConfig.allColumns[i]);
            builder.append(",");
        }
        if (builder.length() > 0) {
            builder.deleteCharAt(builder.length() - 1);
        }
        return builder.toString();
    }


    private static void dropAllTables(Database db, boolean ifExists, @NonNull Class<? extends AbstractDao<?, ?>>... daoClasses) {
        reflectMethod(db, "dropTable", ifExists, daoClasses);
        printLog("【Drop all table by reflect】");
    }

    private static void createAllTables(Database db, boolean ifNotExists, @NonNull Class<? extends AbstractDao<?, ?>>... daoClasses) {
        reflectMethod(db, "createTable", ifNotExists, daoClasses);
        printLog("【Create all table by reflect】");
    }

    /**
     * dao class already define the sql exec method, so just invoke it
     */
    private static void reflectMethod(Database 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();
        }
    }

    /**
     * 存储新的数据库表 以及数据
     *
     * @param db
     * @param daoClasses
     */

    private static void restoreData(Database 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");
            ArrayList<String> properties = new ArrayList();
            ArrayList<String> propertiesQuery = new ArrayList();
            for (int j = 0; j < daoConfig.properties.length; j++) {
                String columnName = daoConfig.properties[j].columnName;

                if (getColumns(db, tempTableName).contains(columnName)) {
                    properties.add(columnName);
                    propertiesQuery.add(columnName);
                } else {
                    try {
                        if (getTypeByClass(daoConfig.properties[j].type).equals("INTEGER")) {
                            propertiesQuery.add("0 as" + columnName);
                            properties.add(columnName);
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }

            StringBuilder insertTableStringBuilder = new StringBuilder();

            insertTableStringBuilder.append("INSERT INTO ").append(tableName).append("(");
            insertTableStringBuilder.append(TextUtils.join(",", properties));
            insertTableStringBuilder.append(") SELECT ");
            insertTableStringBuilder.append(TextUtils.join(",", propertiesQuery));
            insertTableStringBuilder.append(" FROM ").append(tempTableName).append(";");

            StringBuilder dropTableStringBuilder = new StringBuilder();

            dropTableStringBuilder.append("DROP TABLE ").append(tempTableName);

            db.execSQL(insertTableStringBuilder.toString());
            db.execSQL(dropTableStringBuilder.toString());
        }
    }

    private static String getTypeByClass(Class<?> type) throws Exception {
        if (type.equals(String.class)) {
            return "TEXT";
        }
        if (type.equals(Long.class) || type.equals(Integer.class) || type.equals(long.class) || type.equals(int.class)) {
            return "INTEGER";
        }
        if (type.equals(Boolean.class) || type.equals(boolean.class)) {
            return "BOOLEAN";
        }

        Exception exception = new Exception(CONVERSION_CLASS_NOT_FOUND_EXCEPTION.concat("- Class:").concat(type.toString()));
        exception.printStackTrace();
        throw exception;
    }

    private static List<String> getColumns(Database 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;
    }

    private static void printLog(String info) {
        if (DEBUG) {
            Log.d(TAG, info);
        }
    }

}

8.基本使用

获取管理类

dbManager = DbManager.getInstance(this);
entityDao= dbManager.getDaoSession(this).getUserEntityDao();

添加：

UserEntity userEntity =new UserEntity(50,"hello","18");
entityDao.insert(userEntity);

删除：

UserEntity uu= entityDao.queryBuilder().where(UserEntityDao.Properties.Name.eq("hello")).build().unique();
if(uu !=null){
    entityDao.deleteByKey(uu.getId());
}

查询：

List<UserEntity> userList =entityDao.loadAll();
if(userList.size()>0){
    for(UserEntity u:userList){
        Log.i("aaa", "name:= "+u.getName()+"--"+" ID="+u.getId());
    }
}

修改：

UserEntity uu2= entityDao.queryBuilder().where(UserEntityDao.Properties.Name.eq("hello")).build().unique();
if(uu2 !=null){
    uu2.setName("hi");
    entityDao.update(uu2);
}

GreenDao3.0+的基本使用，数据库升级

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