GreenDAO 3.0 資料庫整合，使用，升級
阿新 • • 發佈：2019-02-07
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.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.ArrayList; import java.util.Arrays; import java.util.List; /** * Created by cuiyk on 17-2-28. */ public 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"; public static void migrate(SQLiteDatabase db, Class<? extends AbstractDao<?, ?>>... daoClasses) { Database database = new StandardDatabase(db); printLog("【The Old Database Version】" + db.getVersion()); printLog("【Generate temp table】start"); generateTempTables(database, daoClasses); printLog("【Generate temp table】complete"); 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】"); } private static void createAllTables(Database db, boolean ifNotExists, @NonNull Class<? extends AbstractDao<?, ?>>... daoClasses) { reflectMethod(db, "createTable", ifNotExists, daoClasses); printLog("【Create all table】"); } /** * 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<String> columns = getColumns(db, tempTableName); ArrayList<String> properties = new ArrayList<>(columns.size()); for (int j = 0; j < daoConfig.properties.length; j++) { String columnName = daoConfig.properties[j].columnName; if (columns.contains(columnName)) { properties.add(columnName); } } if (properties.size() > 0) { final String columnSQL = TextUtils.join(",", properties); StringBuilder insertTableStringBuilder = new StringBuilder(); insertTableStringBuilder.append("INSERT INTO ").append(tableName).append(" ("); insertTableStringBuilder.append(columnSQL); insertTableStringBuilder.append(") SELECT "); insertTableStringBuilder.append(columnSQL); 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); } } }
本篇文章基於Android studo開發工具編寫
1、整合
在專案的application目錄的build.gradle檔案里加上如下程式碼
新增完成重新build一下就成功集成了greendao了buildscript { repositories { mavenCentral() } dependencies { classpath 'org.greenrobot:greendao-gradle-plugin:3.2.1' } } apply plugin: 'org.greenrobot.greendao' greendao { schemaVersion 2 //這是修改資料庫版本號，一定要注意位置，在apply plugin: 'org.greenrobot.greendao'下面 } dependencies { compile 'org.greenrobot:greendao:3.2.0' }
2、簡單的使用
建立資料表，每個Entity類就是一個表，如下：
package com.stu.myapplication; import org.greenrobot.greendao.annotation.Entity; import org.greenrobot.greendao.annotation.Id; import org.greenrobot.greendao.annotation.Generated; /** * Created by cuiyk on 17-2-28. */ @Entity public class User { @Id private Long id; private String name; private int age; private String tiem; //下面是build後自動新增的，開發者可以不要自己新增 @Generated(hash = 1634397952) public User(Long id, String name, int age, String tiem) { this.id = id; this.name = name; this.age = age; this.tiem = tiem; } @Generated(hash = 586692638) public User() { } public Long getId() { return this.id; } public void setId(Long id) { this.id = id; } public String getName() { return this.name; } public void setName(String name) { this.name = name; } public int getAge() { return this.age; } public void setAge(int age) { this.age = age; } public String getTiem() { return this.tiem; } public void setTiem(String tiem) { this.tiem = tiem; } }
MigrationHelper類是資料庫升級的輔助類
自定義一個OpenHelper類，為以後資料庫時使用
public class MyOpenHelper extends DaoMaster.OpenHelper {
public MyOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory) {
super(context, name, factory);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
MigrationHelper.migrate(db,UserDao.class);//資料版本變更才會執行
}
}
建立資料庫操作類
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import org.greenrobot.greendao.query.QueryBuilder;
import java.util.List;
/**
* Created by cuiyk on 17-2-28.
*/
public class DBManager {
private final static String dbName = "test_db";
private static DBManager mInstance;
private MyOpenHelper openHelper;
private Context context;
public DBManager(Context context) {
this.context = context;
openHelper = new MyOpenHelper(context, dbName, null);
}
/**
* 獲取單例引用
*
* @param context
* @return
*/
public static DBManager getInstance(Context context) {
if (mInstance == null) {
synchronized (DBManager.class) {
if (mInstance == null) {
mInstance = new DBManager(context);
}
}
}
return mInstance;
}
/**
* 獲取可讀資料庫
*/
private SQLiteDatabase getReadableDatabase() {
if (openHelper == null) {
openHelper = new MyOpenHelper(context, dbName, null);
}
SQLiteDatabase db = openHelper.getReadableDatabase();
return db;
}
/**
* 獲取可寫資料庫
*/
private SQLiteDatabase getWritableDatabase() {
if (openHelper == null) {
openHelper = new MyOpenHelper(context, dbName, null);
}
SQLiteDatabase db = openHelper.getWritableDatabase();
return db;
}
/**
* 插入一條記錄
*
* @param user
*/
public void insertUser(User user) {
DaoMaster daoMaster = new DaoMaster(getWritableDatabase());
DaoSession daoSession = daoMaster.newSession();
UserDao userDao = daoSession.getUserDao();
userDao.insert(user);
}
/**
* 插入使用者集合
*
* @param users
*/
public void insertUserList(List<User> users) {
if (users == null || users.isEmpty()) {
return;
}
DaoMaster daoMaster = new DaoMaster(getWritableDatabase());
DaoSession daoSession = daoMaster.newSession();
UserDao userDao = daoSession.getUserDao();
userDao.insertInTx(users);
}
/**
* 刪除一條記錄
*
* @param user
*/
public void deleteUser(User user) {
DaoMaster daoMaster = new DaoMaster(getWritableDatabase());
DaoSession daoSession = daoMaster.newSession();
UserDao userDao = daoSession.getUserDao();
userDao.delete(user);
}
/**
* 更新一條記錄
*
* @param user
*/
public void updateUser(User user) {
DaoMaster daoMaster = new DaoMaster(getWritableDatabase());
DaoSession daoSession = daoMaster.newSession();
UserDao userDao = daoSession.getUserDao();
userDao.update(user);
}
/**
* 查詢使用者列表
*/
public List<User> queryUserList() {
DaoMaster daoMaster = new DaoMaster(getReadableDatabase());
DaoSession daoSession = daoMaster.newSession();
UserDao userDao = daoSession.getUserDao();
QueryBuilder<User> qb = userDao.queryBuilder();
List<User> list = qb.list();
return list;
}
/**
* 查詢使用者列表
*/
public List<User> queryUserList(int age) {
DaoMaster daoMaster = new DaoMaster(getReadableDatabase());
DaoSession daoSession = daoMaster.newSession();
UserDao userDao = daoSession.getUserDao();
QueryBuilder<User> qb = userDao.queryBuilder();
qb.where(UserDao.Properties.Age.gt(age)).orderAsc(UserDao.Properties.Age);
List<User> list = qb.list();
return list;
}
} DBManager dbManager = DBManager.getInstance(this);
for (int i = 0; i < 5; i++) {
User user = new User();
user.setId((long) i);
user.setAge(i * 3);
user.setName("第" + i + "人");
user.setTiem(String.valueOf(System.currentTimeMillis()));
dbManager.insertUser(user);
}
List<User> userList = dbManager.queryUserList();
userList = dbManager.queryUserList();
for (User user : userList) {
Log.e("TAG", "queryUserList--before-->" + user.getId() + "--" + user.getName() +"--"+user.getAge()+ "--" + user.getTiem());
if (user.getId() == 0) {
dbManager.deleteUser(user);
}
if (user.getId() == 3) {
user.setAge(10);
dbManager.updateUser(user);
}
}
userList = dbManager.queryUserList();
for (User user : userList) {
Log.e("TAG", "queryUserList--after--->" + user.getId() + "---" + user.getName()+"--"+user.getAge() + "--" + user.getTiem());
}