greendao資料庫更新

資料庫更新，例如資料添加一列，greendao操作步驟：

1.生成類GreenDaoGenerator中，修改資料庫版本号

//第一個參數3為資料庫的版本号
Schema schema = new Schema(, "cn.hulutek.budd.resmanager.resmanagerdb.model");
           

修改資料庫變更的實體類

Entity myaudios = schema.addEntity("MyAudios");
        myaudios.addIdProperty().primaryKey().autoincrement();
myaudios.addBooleanProperty("bookmarked");
myaudios.addBooleanProperty("audioadded");
myaudios.addStringProperty("song_name");
myaudios.addStringProperty("chinese_name");
//下面這行為新增的資料庫字段
myaudios.addStringProperty("foreign_name");

myaudios.addStringProperty("tibetan_name");
myaudios.addStringProperty("song_other_name");
myaudios.addStringProperty("song_path");
           

run GreenDaoGenerator，生成新的代碼

2.DaoMaster中，

public static class DevOpenHelper extends OpenHelper {
        public DevOpenHelper(Context context, String name, CursorFactory factory) {
            super(context, name, factory);
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            Log.i("greenDAO", "Upgrading schema from version " + oldVersion + " to " + newVersion + " by dropping all tables");
            //資料庫更新時，建立新的資料庫，遷移資料到新的資料庫
            for(int i=oldVersion;i<=newVersion;i++){               MigrationHelper.getInstance().migrate(db,MyAudiosDao.class,MyScriptureDao.class,MyTributeDao.class);
            }
           /* dropAllTables(db, true);
            onCreate(db);*/
        }
    }
           

至此，資料庫更新成功

其中，MigrationHelper.java

package cn.hulutek.budd.resmanager.resmanagerdb.dao;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.text.TextUtils;
import android.util.Log;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import de.greenrobot.dao.AbstractDao;
import de.greenrobot.dao.internal.DaoConfig;

/**
 * Created by Administrator on 2016/4/18.
 */
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);
    }
    private void generateTempTables(SQLiteDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) {
        for(int i = ; 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 = ; 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) {
                        Crashlytics.logException(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 = ; 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 = ; 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()));
        Crashlytics.logException(exception);
        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;
    }
}