Realm 数据库取代sqlite？，realmsqlite
Realm 是一个orm数据库,适用于android,ios；据说速度超越sqlite(这一点我将在后面有实例验证),还支持json,加密支持
第一步:
compile 'io.realm:realm-android:0.84.1'
第二步:
创建模型:javaBean 必须标准化,字段要私有，要有get set方法，toString方法都不可以有,有严格要求，果真是牺牲自由行来换取速度
package com.xuan.realm.bean;
import io.realm.RealmObject;
/**
* @author xuanyouwu
* @email xuanyouwu@163.com
* @time 2016-05-05 10:02
*/
public class User extends RealmObject {
private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
第三步:创建一个Realm对象
mRealm = Realm.getInstance(this);
保存对象:
User user = new User();
user.setName("hhh");
user.setAge(25);
mRealm.beginTransaction();
mRealm.copyToRealm(user);
mRealm.commitTransaction();查询对象:
RealmResults<User> all = mRealm.where(User.class).findAll();全部代码:
package com.xuan.realm;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import com.xuan.realm.bean.User;
import com.xuan.realm.utils.LogUtils;
import io.realm.Realm;
import io.realm.RealmResults;
public class MainActivity extends AppCompatActivity {
Realm mRealm;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRealm = Realm.getInstance(this);
}
public void onSave(View v) {
User user = new User();
user.setName("hhh");
user.setAge(25);
mRealm.beginTransaction();
mRealm.copyToRealm(user);
mRealm.commitTransaction();
}
public void onQuery(View v) {
RealmResults<User> all = mRealm.where(User.class).findAll();
LogUtils.d("----->query:" + all);
}
}
</pre><pre code_snippet_id="1672753" snippet_file_name="blog_20160505_4_2130749" name="code" class="java">对比:插入100次:<pre name="code" class="java"> long startTime = System.currentTimeMillis();
for (int i = 0; i < 100; i++) {
studentDao.insertData(new Student("name:" + SystemClock.elapsedRealtime(), new Random().nextInt(100)));
}
long endTime = System.currentTimeMillis();
Log.d("-------->sqlite 原生:耗时1:", "" + (endTime - startTime));
long startTime1 = System.currentTimeMillis();
for (int i = 0; i < 100; i++) {
Student1 student1 = new Student1();
student1.setName("name:" + SystemClock.elapsedRealtime());
student1.setAge(new Random().nextInt(100));
daoSession.insertOrReplace(student1);
}
long endTime1 = System.currentTimeMillis();
Log.d("-------->greendao 耗时2:", "" + (endTime1 - startTime1));
long startTime2 = System.currentTimeMillis();
for (int i = 0; i < 100; i++) {
StudentReleam student1 = new StudentReleam();
student1.setName("name:" + SystemClock.elapsedRealtime());
student1.setAge(new Random().nextInt(100));
mRealm.beginTransaction();
mRealm.copyToRealm(student1);
mRealm.commitTransaction();
}
long endTime2 = System.currentTimeMillis();
Log.d("-------->Realm 耗时3:", "" + (endTime2 - startTime2));05-05 03:32:49.561 11993-11993/com.xuan.greendaotest D/-------->sqlite 原生:耗时1:: 605
05-05 03:32:50.246 11993-11993/com.xuan.greendaotest D/-------->greendao 耗时2:: 685
05-05 03:32:50.677 11993-11993/com.xuan.greendaotest D/-------->Realm 耗时3:: 431
查询100次 总时间:
//查询100次
int totalTime = 0;
for (int i = 0; i < 100; i++) {
long startTime = System.currentTimeMillis();
String sql = String.format("select sum(%s) from %s", "age", "student");
Cursor cursor = studentDao.helper.getWritableDatabase().rawQuery(sql, null);
int sumAge = 0;
if (cursor != null && cursor.moveToFirst()) {
sumAge = cursor.getInt(0);
}
long endTime = System.currentTimeMillis();
totalTime += (endTime - startTime);
}
Log.d("-------->sqlite 原生:耗时1:", "" + totalTime);
int totalTime1 = 0;
for (int j = 0; j < 100; j++) {
long startTime1 = System.currentTimeMillis();
/* String sql = String.format("select sum(%s) from %s", "AGE", "STUDENT1");
Cursor cursor = daoSession.getDatabase().rawQuery(sql, null);
int sumAge1 = 0;
if (cursor != null && cursor.moveToFirst()) {
sumAge1 = cursor.getInt(0);
}*/
List<Student1> student1s = daoSession.getStudent1Dao().loadAll();
int sumAge1 = 0;
if (student1s != null) {
for (int i = 0; i < student1s.size(); i++) {
Student1 student1 = student1s.get(i);
if (student1 == null) continue;
sumAge1 += student1.getAge();
}
}
long endTime1 = System.currentTimeMillis();
totalTime1 += (endTime1 - startTime1);
}
Log.d("------->greendao 耗时2:", "" + totalTime1);
int totalTime2 = 0;
for (int j = 0; j < 100; j++) {
long startTime2 = System.currentTimeMillis();
int sumAge2 = 0;
RealmResults<StudentReleam> all = mRealm.where(StudentReleam.class).findAll();
if (all != null) {
for (int i = 0; i < 100; i++) {
StudentReleam student1 = all.get(i);
if (student1 == null) continue;
sumAge2 += student1.getAge();
}
}
long endTime2 = System.currentTimeMillis();
totalTime2 += (endTime2 - startTime2);
}
Log.d("------->realm 耗时3:", "" + totalTime2);
结果:
05-05 03:36:06.226 11993-11993/com.xuan.greendaotest D/-------->sqlite 原生:耗时1:: 1052
05-05 03:36:06.769 11993-11993/com.xuan.greendaotest D/------->greendao 耗时2:: 543
05-05 03:36:07.977 11993-11993/com.xuan.greendaotest D/------->realm 耗时3:: 1208
总结:插入速度 realm>sqlite>greendao
查询速度:sqlite约等于greendao>realm
sqlite 有时候不稳定,几乎和greendao 持平,realm耗时比较稳定，但是几乎是前者的2倍时间
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