Realm
Realm是一個直接在手機，平板電腦或可穿戴設備中運行的移動數據庫。目前僅支持在Android運行。
特性
- 移動數據庫： Realm是第一個直接在手機，平板電腦和可穿戴設備內部運行的數據庫。
- 簡單：數據直接作為對象公開，並且可以通過代碼查詢，從而消除了對ORM充滿性能和維護問題的需求。
- 線程安全： Realm支持簡單的線程安全，關係和加密。
- 性能： Realm在常見操作上比原始SQLite更快，同時保持極其豐富的功能集。
項目熱度
標星： 10635
拷貝： 1670
貢獻人數： 84
最後更新： 2019-09-05
代碼提交活躍度：
推薦指數：【5】顆星
開發語言
開發語言：java
使用方法
在文件build.gradle添加依賴：
buildscript {
repositories {
jcenter()
}
dependencies {
classpath "io.realm:realm-gradle-plugin:5.15.0"
}
}在build.gradle頭部添加：
apply plugin: 'realm-android'
例子：
// Define your model class by extending RealmObject
public class Dog extends RealmObject {
private String name;
private int age;
// ... Generated getters and setters ...
}
public class Person extends RealmObject {
@PrimaryKey
private long id;
private String name;
private RealmList dogs; // Declare one-to-many relationships
// ... Generated getters and setters ...
}
// Use them like regular java objects
Dog dog = new Dog();
dog.setName("Rex");
dog.setAge(1);
// Initialize Realm (just once per application)
Realm.init(context);
// Get a Realm instance for this thread
Realm realm = Realm.getDefaultInstance();
// Query Realm for all dogs younger than 2 years old
final RealmResults puppies = realm.where(Dog.class).lessThan("age", 2).findAll();
puppies.size(); // => 0 because no dogs have been added to the Realm yet
// Persist your data in a transaction
realm.beginTransaction();
final Dog managedDog = realm.copyToRealm(dog); // Persist unmanaged objects
Person person = realm.createObject(Person.class); // Create managed objects directly
person.getDogs().add(managedDog);
realm.commitTransaction();
// Listeners will be notified when data changes
puppies.addChangeListener(new OrderedRealmCollectionChangeListener>() {
@Override
public void onChange(RealmResults results, OrderedCollectionChangeSet changeSet) {
// Query results are updated in real time with fine grained notifications.
changeSet.getInsertions(); // => [0] is added.
}
});
// Asynchronously update objects on a background thread
realm.executeTransactionAsync(new Realm.Transaction() {
@Override
public void execute(Realm bgRealm) {
Dog dog = bgRealm.where(Dog.class).equalTo("age", 1).findFirst();
dog.setAge(3);
}
}, new Realm.Transaction.OnSuccess() {
@Override
public void onSuccess() {
// Original queries and Realm objects are automatically updated.
puppies.size(); // => 0 because there are no more puppies younger than 2 years old
managedDog.getAge(); // => 3 the dogs age is updated
}
});
項目地址
https://github.com/realm/realm-java
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