1. 集成GreenDao
GeenDao 官网
github: https://github.com/greenrobot/greenDAO
-(1)应用Model build.gradle中添加
apply plugin: 'org.greenrobot.greendao'
应用Model build.gradle 的dependencies 下添加
implementation 'org.greenrobot:greendao:3.2.2'
如果要通过sqlcipher对数据库进行加密添加
implementation 'net.zetetic:android-database-sqlcipher:3.5.9'
如下图
1.PNG
-(2)项目的根build.gradle中添加
classpath 'org.greenrobot:greendao-gradle-plugin:3.2.2'
2.PNG
-(3)添加混淆配置
-keepclassmembers class * extends org.greenrobot.greendao.AbstractDao {
public static java.lang.String TABLENAME;
}
-keep class **$Properties {*;}
#sqlcipher数据库加密开始
-keep class net.sqlcipher.** {*;}
-keep class net.sqlcipher.database.** {*;}
#sqlcipher数据库加密开始
如果没有使用加密和RxJava则使用以下配置
-keepclassmembers class * extends org.greenrobot.greendao.AbstractDao {
public static java.lang.String TABLENAME;
}
-keep class **$Properties {*;}
#If you do not use SQLCipher:
-dontwarn net.sqlcipher.database.**
#If you do not use RxJava:
-dontwarn rx.**
2. GreenDao的使用
-(1)创建实体类
@Entity
public class StudyItem {
@Id(autoincrement = true)
private Long id;
@NotNull
private String colorName;
@NotNull
private String colorId;
注意id 为Long 自动增长，不能使用long，否则数据库升级会有问题。
-(2)实体类编写后，应用Model下配置 build.gradle android{} 中添加以下配置
greendao {
schemaVersion 1 //数据库版本号
daoPackage 'com.gao.sun.it.db' //设置DaoMaster.DaoSession,Dao包名
targetGenDir 'src/main/java' //设置daoPackage所在的文件路径
}
点击Build-->Make Project，在目标文件夹中（上面配置的是daoPackage 'com.gao.sun.it.db'）会自动生成DaoMaster 、DaoSession、以及实体类对应的XXXXDao。
具体使用，例如保存数据
DaoMaster.DevOpenHelper devOpenHelper = new DaoMaster.DevOpenHelper(mContext, DB_NAME);
mDaoMaster = new DaoMaster(devOpenHelper.getWritableDb());
mDaoSession = mDaoMaster.newSession();
mDaoSession.insert(实例对象);
后面再记录具体的保存、查询、删除数据等。
-(3)数据库的升级
当数据表需要增加字段、删除字段等需要升级数据库。目前的GreenDao升级数据库时，只需要将以下配置中的版本号增加1
greendao {
schemaVersion 1 //数据库版本号
daoPackage 'com.gao.sun.it.db' //设置DaoMaster.DaoSession,Dao包名
targetGenDir 'src/main/java' //设置daoPackage所在的文件路径
}
数据表确实会完成升级，但原来的数据会丢失。
要想完成数据表的升级并且保留以前的数据，需要写一个类继承DaoMaster.DevOpenHelper并且重写onUpgrade完成数据的迁移。
public class DBHelper extends DaoMaster.DevOpenHelper {
public DBHelper(Context context, String name) {
super(context, name);
}
public DBHelper(Context context, String name, SQLiteDatabase.CursorFactory factory) {
super(context, name, factory);
}
@Override
public void onUpgrade(Database db, int oldVersion, int newVersion) {
//把需要管理的数据库表DAO作为最后一个参数传入到方法中
MigrationHelper.migrate(db, new MigrationHelper.ReCreateAllTableListener() {
@Override
public void onCreateAllTables(Database db, boolean ifNotExists) {
DaoMaster.createAllTables(db, ifNotExists);
}
@Override
public void onDropAllTables(Database db, boolean ifExists) {
DaoMaster.dropAllTables(db, ifExists);
}
},xxxxDao.class,xxxDao.class); //所有的xxxDao.classs
}
}
其中MigrationHelper是一个工具类，别人写好的。
https://github.com/yuweiguocn/GreenDaoUpgradeHelper
当表中字段，也就是实体类中属性增加或者删除时，重新Make Project，同时将版本号增加1，就会完成数据库升级。
MigrationHelper代码如下：
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.support.annotation.NonNull;
import android.text.TextUtils;
import android.util.Log;
import org.greenrobot.greendao.AbstractDao;
import org.greenrobot.greendao.database.Database;
import org.greenrobot.greendao.database.StandardDatabase;
import org.greenrobot.greendao.internal.DaoConfig;
import java.lang.ref.WeakReference;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
*
* please call {@link #migrate(SQLiteDatabase, Class[])} or {@link #migrate(Database, Class[])}
*
*/
public final class MigrationHelper {
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 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");
}
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();
}
}
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");
if (!isTableExists(db, true, tempTableName)) {
continue;
}
try {
// get all columns from tempTable, take careful to use the columns list
List<TableInfo> newTableInfos = TableInfo.getTableInfo(db, tableName);
List<TableInfo> tempTableInfos = TableInfo.getTableInfo(db, tempTableName);
ArrayList<String> selectColumns = new ArrayList<>(newTableInfos.size());
ArrayList<String> intoColumns = new ArrayList<>(newTableInfos.size());
for (TableInfo tableInfo : tempTableInfos) {
if (newTableInfos.contains(tableInfo)) {
String column = '`' + tableInfo.name + '`';
intoColumns.add(column);
selectColumns.add(column);
}
}
// NOT NULL columns list
for (TableInfo tableInfo : newTableInfos) {
if (tableInfo.notnull && !tempTableInfos.contains(tableInfo)) {
String column = '`' + tableInfo.name + '`';
intoColumns.add(column);
String value;
if (tableInfo.dfltValue != null) {
value = "'" + tableInfo.dfltValue + "' AS ";
} else {
value = "'' AS ";
}
selectColumns.add(value + column);
}
}
if (intoColumns.size() != 0) {
StringBuilder insertTableStringBuilder = new StringBuilder();
insertTableStringBuilder.append("REPLACE INTO `").append(tableName).append("` (");
insertTableStringBuilder.append(TextUtils.join(",", intoColumns));
insertTableStringBuilder.append(") SELECT ");
insertTableStringBuilder.append(TextUtils.join(",", selectColumns));
insertTableStringBuilder.append(" FROM ").append(tempTableName).append(";");
db.execSQL(insertTableStringBuilder.toString());
printLog("【Restore data】 to " + tableName);
}
StringBuilder dropTableStringBuilder = new StringBuilder();
dropTableStringBuilder.append("DROP TABLE ").append(tempTableName);
db.execSQL(dropTableStringBuilder.toString());
printLog("【Drop temp table】" + tempTableName);
} catch (SQLException e) {
Log.e(TAG, "【Failed to restore data from temp table 】" + tempTableName, e);
}
}
}
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);
}
}
private static class TableInfo {
int cid;
String name;
String type;
boolean notnull;
String dfltValue;
boolean pk;
@Override
public boolean equals(Object o) {
return this == o
|| o != null
&& getClass() == o.getClass()
&& name.equals(((TableInfo) o).name);
}
@Override
public String toString() {
return "TableInfo{" +
"cid=" + cid +
", name='" + name + '\'' +
", type='" + type + '\'' +
", notnull=" + notnull +
", dfltValue='" + dfltValue + '\'' +
", pk=" + pk +
'}';
}
private static List<TableInfo> getTableInfo(Database db, String tableName) {
String sql = "PRAGMA table_info(`" + tableName + "`)";
printLog(sql);
Cursor cursor = db.rawQuery(sql, null);
if (cursor == null)
return new ArrayList<>();
TableInfo tableInfo;
List<TableInfo> tableInfos = new ArrayList<>();
while (cursor.moveToNext()) {
tableInfo = new TableInfo();
tableInfo.cid = cursor.getInt(0);
tableInfo.name = cursor.getString(1);
tableInfo.type = cursor.getString(2);
tableInfo.notnull = cursor.getInt(3) == 1;
tableInfo.dfltValue = cursor.getString(4);
tableInfo.pk = cursor.getInt(5) == 1;
tableInfos.add(tableInfo);
// printLog(tableName + "：" + tableInfo);
}
cursor.close();
return tableInfos;
}
}
}
2. GreenDao完成增删改查
未完待续
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