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);
}
}
}
本篇文章基于Android studo開發工具編寫
1、內建
參考官方文檔 https://github.com/greenrobot/greenDAO
在項目的application目錄的build.gradle檔案裡加上如下代碼
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号,一定要注意位置,在apply plugin: 'org.greenrobot.greendao'下面
}
dependencies {
compile 'org.greenrobot:greendao:3.2.0'
}
添加完成重新build一下就成功內建了greendao了
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後自動添加的,開發者可以不要自己添加
@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類是資料庫更新的輔助類
來源于 https://github.com/yuweiguocn/GreenDaoUpgradeHelper 我是直接搬過來的
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);
}
/**
* 擷取單例引用
*
* @param context
* @return
*/
public static DBManager getInstance(Context context) {
if (mInstance == null) {
synchronized (DBManager.class) {
if (mInstance == null) {
mInstance = new DBManager(context);
}
}
}
return mInstance;
}
/**
* 擷取可讀資料庫
*/
private SQLiteDatabase getReadableDatabase() {
if (openHelper == null) {
openHelper = new MyOpenHelper(context, dbName, null);
}
SQLiteDatabase db = openHelper.getReadableDatabase();
return db;
}
/**
* 擷取可寫資料庫
*/
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);
}
/**
* 删除一條記錄
*
* @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);
}
/**
* 查詢使用者清單
*/
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;
}
/**
* 查詢使用者清單
*/
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;
}
}
測試調用
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());
}