上一次粗略地读了一下TableInfo这个类，了解了一下ActiveAndroid中注解的使用方法，算是一个预热，这一篇，从正常的顺序开始。
所以，这次从ActiveAndroid的初始化开始阅读。
public class Application extends android.app.Application { @Override public void onCreate() { super.onCreate(); ActiveAndroid.initialize(this); } @Override public void onTerminate() { super.onTerminate(); ActiveAndroid.dispose(); } }
先看ActiveAndroid.initialize(this);。
public final class ActiveAndroid { ////////////////////////////////////////////////////////////////////////////////////// // PUBLIC METHODS ////////////////////////////////////////////////////////////////////////////////////// public static void initialize(Context context) { initialize(new Configuration.Builder(context).create()); }
……
}
只能先看看Configuration这个类。
public class Configuration { public final static String SQL_PARSER_LEGACY = "legacy"; public final static String SQL_PARSER_DELIMITED = "delimited"; …… public static class Builder { ////////////////////////////////////////////////////////////////////////////////////// // PRIVATE CONSTANTS ////////////////////////////////////////////////////////////////////////////////////// private static final String AA_DB_NAME = "AA_DB_NAME"; private static final String AA_DB_VERSION = "AA_DB_VERSION"; private final static String AA_MODELS = "AA_MODELS"; private final static String AA_SERIALIZERS = "AA_SERIALIZERS"; private final static String AA_SQL_PARSER = "AA_SQL_PARSER"; private static final int DEFAULT_CACHE_SIZE = 1024; private static final String DEFAULT_DB_NAME = "Application.db"; private static final String DEFAULT_SQL_PARSER = SQL_PARSER_LEGACY; ////////////////////////////////////////////////////////////////////////////////////// // PRIVATE MEMBERS ////////////////////////////////////////////////////////////////////////////////////// private Context mContext; private Integer mCacheSize; private String mDatabaseName; private Integer mDatabaseVersion; private String mSqlParser; private List<Class<? extends Model>> mModelClasses; private List<Class<? extends TypeSerializer>> mTypeSerializers; ////////////////////////////////////////////////////////////////////////////////////// // CONSTRUCTORS ////////////////////////////////////////////////////////////////////////////////////// public Builder(Context context) { mContext = context.getApplicationContext(); mCacheSize = DEFAULT_CACHE_SIZE; } …… public Configuration create() { Configuration configuration = new Configuration(mContext); configuration.mCacheSize = mCacheSize; // Get database name from meta-data if (mDatabaseName != null) { configuration.mDatabaseName = mDatabaseName; } else { configuration.mDatabaseName = getMetaDataDatabaseNameOrDefault(); } // Get database version from meta-data if (mDatabaseVersion != null) { configuration.mDatabaseVersion = mDatabaseVersion; } else { configuration.mDatabaseVersion = getMetaDataDatabaseVersionOrDefault(); } // Get SQL parser from meta-data if (mSqlParser != null) { configuration.mSqlParser = mSqlParser; } else { configuration.mSqlParser = getMetaDataSqlParserOrDefault(); } // Get model classes from meta-data if (mModelClasses != null) { configuration.mModelClasses = mModelClasses; } else { final String modelList = ReflectionUtils.getMetaData(mContext, AA_MODELS); if (modelList != null) { configuration.mModelClasses = loadModelList(modelList.split(",")); } } // Get type serializer classes from meta-data if (mTypeSerializers != null) { configuration.mTypeSerializers = mTypeSerializers; } else { final String serializerList = ReflectionUtils.getMetaData(mContext, AA_SERIALIZERS); if (serializerList != null) { configuration.mTypeSerializers = loadSerializerList(serializerList.split(",")); } } return configuration; } …… }
其中，最关键的就是create()这个方法。
我们来逐行分析：
首先，configuration获得application的context和缓存大小，默认的缓存大小为1024;
Configuration configuration = new Configuration(mContext); configuration.mCacheSize = mCacheSize;
第二步，获得database的name;
// Get database name from meta-data if (mDatabaseName != null) { configuration.mDatabaseName = mDatabaseName; } else { configuration.mDatabaseName = getMetaDataDatabaseNameOrDefault(); }
其中,
// Meta-data methods private String getMetaDataDatabaseNameOrDefault() { String aaName = ReflectionUtils.getMetaData(mContext, AA_DB_NAME); if (aaName == null) { aaName = DEFAULT_DB_NAME; } return aaName; }
@SuppressWarnings("unchecked")
public static <T> T getMetaData(Context context, String name) {
try {
final ApplicationInfo ai = context.getPackageManager().getApplicationInfo(context.getPackageName(),
PackageManager.GET_META_DATA);
if (ai.metaData != null) {
return (T) ai.metaData.get(name);
}
}
catch (Exception e) {
Log.w("Couldn't find meta-data: " + name);
}
return null;
}
用java动态取出Androidmanifest中，关于数据库的信息。
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.dream.fishbonelsy.baseonlsy" > <application android:name=".MyApplication" android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <meta-data android:name="AA_DB_NAME" android:value="Longsiyang.db" /> <meta-data android:name="AA_DB_VERSION" android:value="2" /> ……
通过以上代码获得了数据库的name:Longsiyang.db
第三步获得数据库版本号;
// Get database version from meta-data if (mDatabaseVersion != null) { configuration.mDatabaseVersion = mDatabaseVersion; } else { configuration.mDatabaseVersion = getMetaDataDatabaseVersionOrDefault(); }
与第二步原理相同，获得版本号。
第四步获得
// Get SQL parser from meta-data if (mSqlParser != null) { configuration.mSqlParser = mSqlParser; } else { configuration.mSqlParser = getMetaDataSqlParserOrDefault(); }
private String getMetaDataSqlParserOrDefault() { final String mode = ReflectionUtils.getMetaData(mContext, AA_SQL_PARSER); if (mode == null) { return DEFAULT_SQL_PARSER; } return mode; }
默认情况下，mode==null，所以
public final static String SQL_PARSER_LEGACY = "legacy"; private static final String DEFAULT_SQL_PARSER = SQL_PARSER_LEGACY;
至此，Conguration的默认初始化已经完成。总结一下，Conguration类存储了数据库的：缓存大小、数据库名称、数据库版本号、数据库parser。有了这些信息，我们就可以建数据库了。
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public final class ActiveAndroid { ////////////////////////////////////////////////////////////////////////////////////// // PUBLIC METHODS ////////////////////////////////////////////////////////////////////////////////////// public static void initialize(Context context) { initialize(new Configuration.Builder(context).create()); } …… }
回到这里，我们继续读initialize方法。进入initialize：
public static synchronized void initialize(Configuration configuration) { if (sIsInitialized) { Log.v("ActiveAndroid already initialized."); return; } sContext = configuration.getContext(); sModelInfo = new ModelInfo(configuration); sDatabaseHelper = new DatabaseHelper(configuration); // TODO: It would be nice to override sizeOf here and calculate the memory // actually used, however at this point it seems like the reflection // required would be too costly to be of any benefit. We'll just set a max // object size instead. sEntities = new LruCache<String, Model>(configuration.getCacheSize()); openDatabase(); sIsInitialized = true; Log.v("ActiveAndroid initialized successfully."); }
在这里，将Conguration信息传入ModelInfo，并打开数据库，将标志位sIsInitialized打开。
接下来的一篇，将继续阅读打开数据库的相关代码。
Done!
