寫了2天的代碼，總結一下這兩天的一些積累
realm簡單來說就是一個可以代替sql的數據庫， 特點：易用，快速，跨平臺，專業（支持加密，格式化查詢，易于移植，支持JSON，流式api，數據變更通知）， 可視化
官方網站 https://realm.io/docs/java/latest/ 有需要的朋友，可以去看看
代碼：

1、配置
在最外面的那層build.gradle 配置這一段代碼

classpath "io.realm:realm-gradle-plugin:5.8.0"

然后在app文件里面的build.gradle 配置這一段代碼

apply plugin: 'realm-android'

1、布局

3、代碼
3.1創建一個需要保存數據庫的類，我寫了兩個

import io.realm.RealmObject;/*** @author Admin* https://realm.io/docs/java/latest/*/ public class Dog extends RealmObject {String name;String age;String aihao;public String getName() {return name;}public void setName(String name) {this.name = name;}public String getAge() {return age;}public void setAge(String age) {this.age = age;}public String getAihao() {return aihao;}public void setAihao(String aihao) {this.aihao = aihao;}@Overridepublic String toString() {return "Dog{" +"name='" + name + '\'' +", age='" + age + '\'' +", aihao='" + aihao + '\'' +'}';} } import io.realm.RealmList; import io.realm.RealmObject; /*** @author Admin* https://realm.io/docs/java/latest/*/ public class MyRealmDemo extends RealmObject {String userName;String pwd;Long sessionId;private RealmList<Integer> Remarks = new RealmList<>();public String getUserName() {return userName;}public void setUserName(String userName) {this.userName = userName;}public String getPwd() {return pwd;}public void setPwd(String pwd) {this.pwd = pwd;}public Long getSessionId() {return sessionId;}public void setSessionId(Long sessionId) {this.sessionId = sessionId;}public RealmList<Integer> getRemarks() {return Remarks;}public void setRemarks(RealmList<Integer> remarks) {Remarks = remarks;}@Overridepublic String toString() {return "MyRealmDemo{" +"userName='" + userName + '\'' +", pwd='" + pwd + '\'' +", sessionId=" + sessionId +", Remarks=" + Remarks.size() +'}';} }

3.2 創建一個Application，在onCreate里面進行初始化

import io.realm.Realm; import io.realm.RealmConfiguration; /*** @author Admin*/ public class MyApplication extends Application {public static RealmConfiguration config;@Overridepublic void onCreate() {super.onCreate();Realm.init(this);config = new RealmConfiguration.Builder().name("myRealm.realm").deleteRealmIfMigrationNeeded().build();Realm.setDefaultConfiguration(config);//配置默認的數據庫//setDefaultConfiguration(new RealmConfiguration.Builder().build()); // RealmConfiguration configuration = new RealmConfiguration.Builder().build();} }

3.3 主界面的實現代碼

import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.TextView; import android.widget.Toast;import io.realm.Realm; import io.realm.RealmAsyncTask; import io.realm.RealmResults;/*** @author Admin*/ public class MainActivity extends AppCompatActivity implements View.OnClickListener {TextView txtShow;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initRealm();txtShow = findViewById(R.id.txt_show);findViewById(R.id.btn_add).setOnClickListener(this);findViewById(R.id.btn_search).setOnClickListener(this);findViewById(R.id.btn_delete).setOnClickListener(this);findViewById(R.id.btn_update).setOnClickListener(this);}Realm realm;Integer index = 0;RealmAsyncTask transaction;private void initRealm() {realm = Realm.getInstance(MyApplication.config);}/*** 升級數據庫*/ // class CustomMigration implements RealmMigration { // @Override // public void migrate(DynamicRealm realm, long oldVersion, long newVersion) { // RealmSchema schema = realm.getSchema(); // Log.e("MainActivity", "oldVersion：" + oldVersion + "----newVersion" + newVersion); // if (oldVersion == 1 && newVersion == 2) { // RealmObjectSchema personSchema = schema.get("Dog"); // if (!personSchema.hasField("Dog")) { personSchema.addField("aihao", String.class, FieldAttribute.REQUIRED); oldVersion++; } // // } // } // }private void addRealm() {transaction = realm.executeTransactionAsync(realm -> {MyRealmDemo myDemo = realm.createObject(MyRealmDemo.class);myDemo.setUserName("名字");myDemo.setPwd(index + "");myDemo.getRemarks().add(index);index++;}, () -> {//成功回調Log.e("MainActivity", "成功回調" + index);}, error -> {//失敗回調Log.e("MainActivity", "失敗");});transaction = realm.executeTransactionAsync(realm -> {Dog dog = realm.createObject(Dog.class);dog.setName("哈士奇");dog.setAge(index + "歲");dog.setAihao("拆家" + index);}, () -> {//成功回調Log.e("MainActivity", "成功回調" + index);}, error -> {//失敗回調Log.e("MainActivity", "失敗");});}private void updateRealm() {transaction = realm.executeTransactionAsync(realm -> {RealmResults<MyRealmDemo> myList = realm.where(MyRealmDemo.class).findAll();if (myList != null && myList.size() > 0) {MyRealmDemo myDemo = myList.get(0);myDemo.setUserName("換名字");myDemo.setPwd("小球不得");myDemo.getRemarks().add(index);index++;} else {Log.e("MainActivity", "updateRealm沒得東西，改毛線" + index);Toast.makeText(this, "updateRealm沒得東西，改毛線", Toast.LENGTH_SHORT).show();}}, () -> {//成功回調Log.e("MainActivity", "成功回調" + index);}, error -> {//失敗回調error.printStackTrace();Log.e("MainActivity", "失敗" + error.getMessage());});}private void deleteRealm() {transaction = realm.executeTransactionAsync(realm -> {RealmResults<MyRealmDemo> myList = realm.where(MyRealmDemo.class).findAll();//刪除第一個數據myList.get(0).deleteFromRealm(); // myList.deleteFirstFromRealm(); // //刪除最后一個數據 // myList.deleteLastFromRealm(); // //刪除位置為1的數據 // myList.deleteFromRealm(1); // //刪除所有數據 // myList.deleteAllFromRealm();}, () -> {//成功回調Log.e("MainActivity", "deleteRealm刪球了" + index);}, error -> {//失敗回調Log.e("MainActivity", "deleteRealm沒刪拖");});}private void searchRealm() {RealmResults<MyRealmDemo> myList = realm.where(MyRealmDemo.class).findAll();String strText = "";if (myList != null && myList.size() > 0) {for (MyRealmDemo myRealmDemo : myList) {strText += "\n看什么玩意嘛：" + myRealmDemo.toString();Log.e("MainActivity", "看什么玩意嘛：" + myRealmDemo.toString());for (int intNum : myRealmDemo.getRemarks()) {strText += "\n數組里的東西：" + intNum;Log.e("MainActivity", "數組里的東西：" + intNum);}}} else {Log.e("MainActivity", "空的，代碼錯了，看錘子");}RealmResults<Dog> dogList = realm.where(Dog.class).findAll();for (Dog dog : dogList) {strText += "\n我的狗：" + dog.toString();Log.e("MainActivity", "我的狗：" + dog.toString());}txtShow.setText(strText);}@Overridepublic void onClick(View v) {switch (v.getId()) {case R.id.btn_add://添加addRealm();break;case R.id.btn_search://查詢searchRealm();break;case R.id.btn_delete://刪除deleteRealm();break;case R.id.btn_update://修改updateRealm();break;default:break;}}@Overrideprotected void onStop() {super.onStop();//取消當前的數據庫操作狀態if (transaction != null && !transaction.isCancelled()) {transaction.cancel();}}@Overrideprotected void onDestroy() {super.onDestroy();//關閉連接realm.close();} }

效果圖：

源碼：
https://github.com/StrangerYang/testRealm

總結

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