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GreenDao升级数据库工具类

GreenDao升级数据库工具类

作者: up2159 | 来源:发表于2018-12-27 16:27 被阅读0次
    /**
     * @author liutx 
     */
    public class MigrationHelper {
        private static final String CONVERSION_CLASS_NOT_FOUND_EXCEPTION =
                "MIGRATION HELPER - CLASS DOESN'T MATCH WITH THE CURRENT PARAMETERS";
        private static MigrationHelper instance;
    
        public static MigrationHelper getInstance() {
            if (instance == null) {
                instance = new MigrationHelper();
            }
            return instance;
        }
    
        public void migrate(SQLiteDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
            generateTempTables(db, daoClasses);
            DaoMaster.dropAllTables(db, true);
            DaoMaster.createAllTables(db, false);
            restoreData(db, daoClasses);
            Log.i("greenDAO","MigrationHelper---migrate");
        }
    
        private void generateTempTables(SQLiteDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
            for (int i = 0; i < daoClasses.length; i++) {
                DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);
    
                String divider = "";
                String tableName = daoConfig.tablename;
                String tempTableName = daoConfig.tablename.concat("_TEMP");
                ArrayList<String> properties = new ArrayList<>();
    
                StringBuilder createTableStringBuilder = new StringBuilder();
    
                createTableStringBuilder.append("CREATE TABLE ").append(tempTableName).append(" (");
    
                for (int j = 0; j < daoConfig.properties.length; j++) {
                    String columnName = daoConfig.properties[j].columnName;
    
                    if (getColumns(db, tableName).contains(columnName)) {
                        properties.add(columnName);
    
                        String type = null;
    
                        try {
                            type = getTypeByClass(daoConfig.properties[j].type);
                        } catch (Exception exception) {
                        }
    
                        createTableStringBuilder.append(divider).append(columnName).append(" ").append(type);
    
                        if (daoConfig.properties[j].primaryKey) {
                            createTableStringBuilder.append(" PRIMARY KEY");
                        }
    
                        divider = ",";
                    }
                }
                createTableStringBuilder.append(");");
    
                db.execSQL(createTableStringBuilder.toString());
    
                StringBuilder insertTableStringBuilder = new StringBuilder();
    
                insertTableStringBuilder.append("INSERT INTO ").append(tempTableName).append(" (");
                insertTableStringBuilder.append(TextUtils.join(",", properties));
                insertTableStringBuilder.append(") SELECT ");
                insertTableStringBuilder.append(TextUtils.join(",", properties));
                insertTableStringBuilder.append(" FROM ").append(tableName).append(";");
    
                db.execSQL(insertTableStringBuilder.toString());
            }
        }
    
        private void restoreData(SQLiteDatabase 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<>();
    
                for (int j = 0; j < daoConfig.properties.length; j++) {
                    String columnName = daoConfig.properties[j].columnName;
    
                    if (getColumns(db, tempTableName).contains(columnName)) {
                        properties.add(columnName);
                    }
                }
    
                StringBuilder insertTableStringBuilder = new StringBuilder();
    
                insertTableStringBuilder.append("INSERT INTO ").append(tableName).append(" (");
                insertTableStringBuilder.append(TextUtils.join(",", properties));
                insertTableStringBuilder.append(") SELECT ");
                insertTableStringBuilder.append(TextUtils.join(",", properties));
                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 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)) {
                return "INTEGER";
            }
            if (type.equals(Boolean.class)) {
                return "BOOLEAN";
            }
    
            Exception exception =
                    new Exception(CONVERSION_CLASS_NOT_FOUND_EXCEPTION.concat(" - Class: ").concat(type.toString()));
            throw exception;
        }
    
        private static List<String> getColumns(SQLiteDatabase db, String tableName) {
            List<String> columns = new ArrayList<>();
            Cursor cursor = null;
            try {
                cursor = db.rawQuery("SELECT * FROM " + tableName + " limit 1", null);
                if (cursor != null) {
                    columns = new ArrayList<>(Arrays.asList(cursor.getColumnNames()));
                }
            } catch (Exception e) {
                Log.v(tableName, e.getMessage(), e);
                e.printStackTrace();
            } finally {
                if (cursor != null) cursor.close();
            }
            return columns;
        }
    
    }
    

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