1.在project的gradle里添加： classpath "io.realm:realm-gradle-plugin:3.0.0"
2.在APP的gradle里添加： apply plugin: ‘realm-android’
3.建立MyApplication，并在AndroidManifest.xml配置自定义的Application：
public class MyApplication extends Application {
@Override
public void onCreate() {
super.onCreate();
Realm.init(this);
//默认配置
// RealmConfiguration config = new RealmConfiguration.Builder().build();
//自定义配置
RealmConfiguration config = new RealmConfiguration.Builder()
.name("myRealm.realm")
.deleteRealmIfMigrationNeeded()
.build();
Realm.setDefaultConfiguration(config);
}
}
4.新建一个类继承RealmObject:
public class User extends RealmObject {
@PrimaryKey
private String id;
private String name;
private String email;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String toString() {
return "student:id="+ id +" name=" + name +"email=" + email + "\n";
}
}
5.增删改查:
/**
* 增加
*/
public void addObject() {
// //实现方法一：事务操作
// //类型一 ：新建一个对象，并进行存储
// Realm realm=Realm.getDefaultInstance();
// realm.beginTransaction();
// User user = realm.createObject(User.class); // Create a new object
// user.setName("John");
// user.setEmail("john@corporation.com");
// realm.commitTransaction();
// //类型二：复制一个对象到Realm数据库
// Realm realm=Realm.getDefaultInstance();
// User user = new User("John");
// user.setEmail("john@corporation.com");
// realm.beginTransaction();
// realm.copyToRealm(user);
// realm.commitTransaction();
//实现方法二：使用事务块
Realm mRealm = Realm.getDefaultInstance();
final User user = new User();
user.setEmail("john" + number + "@corporation.com");
user.setId(String.valueOf(number));
user.setName("John" + number);
try{
mRealm.executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
realm.copyToRealm(user);
tvShowResult.setText(" 增加成功:" + user.toString());
}
});
}catch (Exception e){
number++;
e.printStackTrace();
tvShowResult.setText(" 增加失败");
}
}
/**
* 删除
* 同样也可以使用同addObject函数的beginTransaction和commitTransaction方法进行删除
*/
public void deleteObject() {
final int positon = 1;
Realm mRealm = Realm.getDefaultInstance();
final RealmResults<User> users = mRealm.where(User.class).findAll();
try {
mRealm.executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
if (users.size() > 0) {
User user = users.get(positon);
String str = user.toString();
user.deleteFromRealm();
tvShowResult.setText("删除成功\n" + str);
// //删除第一个数据
// users.deleteFirstFromRealm();
// //删除最后一个数据
// users.deleteLastFromRealm();
// //删除位置为1的数据
// users.deleteFromRealm(1);
// //删除所有数据
// users.deleteAllFromRealm();
} else {
tvShowResult.setText("user表里无数据");
}
}
});
}catch (Exception e){
e.printStackTrace();
tvShowResult.setText("删除失败");
}
}
/**
* 修改
*/
public void updateObject() {
try{
String id = "1";
String newName = "玫玫";
Realm mRealm = Realm.getDefaultInstance();
User user = mRealm.where(User.class).equalTo("id", id).findFirst();
mRealm.beginTransaction();
user.setName(newName);
mRealm.commitTransaction();
tvShowResult.setText("更新\n" + user.toString());
}catch (Exception e){
e.printStackTrace();
tvShowResult.setText(" 更新失败");
}
}
/**
* 查询所有数据
*/
public void queryAllObject() {
Realm mRealm = Realm.getDefaultInstance();
RealmResults<User> users = mRealm.where(User.class).findAll();
/**
* 对查询结果，按Id进行排序，只能对查询结果进行排序
*/
// //增序排列
// users=users.sort("id");
//降序排列
users = users.sort("id", Sort.DESCENDING);
String str = "";
for (int i = 0; i < users.size(); i++) {
User user = users.get( i);
str = str + user.toString();
}
tvShowResult.setText("查询所有数据：\n" + str);
}
}
异步操作：
@OnClick({R.id.tv_asy_add, R.id.tv_asy_delete, R.id.tv_asy_update, R.id.tv_asy_query})
public void onViewClicked(View view) {
switch (view.getId()) {
case R.id.tv_asy_add:
User user = new User();
user.setEmail("john" + number + "@corporation.com");
user.setId(String.valueOf(number));
user.setName("John" + number);
addUser( user );
number++;
break;
case R.id.tv_asy_delete:
String id = "1";
deleteUser( id);
break;
case R.id.tv_asy_update:
String Id = "2";
String name = "玫玫";
updateUser( name,Id );
break;
case R.id.tv_asy_query:
queryUser();
break;
}
}
/**
* 增加
* @param user
*/
private void addUser(final User user) {
Realm mRealm = Realm.getDefaultInstance();
addTask= mRealm.executeTransactionAsync(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
realm.copyToRealm(user);
}
}, new Realm.Transaction.OnSuccess() {
@Override
public void onSuccess() {
tvShowResult.setText( "增加成功" + user.toString());
}
}, new Realm.Transaction.OnError() {
@Override
public void onError(Throwable error) {
tvShowResult.setText( "增加失败");
}
});
}
/**
* 删除
* @param id
*/
private void deleteUser(final String id){
Realm mRealm = Realm.getDefaultInstance();
final String[] str = {""};
deleteTask= mRealm.executeTransactionAsync(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
User user=realm.where(User.class).equalTo("id",id).findFirst();
str[0] = user.toString();
user.deleteFromRealm();
}
}, new Realm.Transaction.OnSuccess() {
@Override
public void onSuccess() {
tvShowResult.setText( "删除成功" + str[0] );
}
}, new Realm.Transaction.OnError() {
@Override
public void onError(Throwable error) {
tvShowResult.setText( "删除失败" + str[0] );
}
});
}
/**
* 修改
* @param name
* @param id
*/
private void updateUser(final String name, final String id){
Realm mRealm = Realm.getDefaultInstance();
final String[] oldStr = {""};
final String[] newStr = {""};
updateTask = mRealm.executeTransactionAsync(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
User user=realm.where(User.class).equalTo("id",id).findFirst();
oldStr[0] = user.toString();
user.setName(name);
newStr[0] = user.toString();
}
}, new Realm.Transaction.OnSuccess() {
@Override
public void onSuccess() {
tvShowResult.setText( "旧信息:" + oldStr[0] + "\n修改成功\n" + newStr[0]);
}
}, new Realm.Transaction.OnError() {
@Override
public void onError(Throwable error) {
tvShowResult.setText( "旧信息:" + oldStr[0] + "\n修改失败");
}
});
}
/**
* 查询所有数据
*/
private void queryUser(){
final Realm mRealm = Realm.getDefaultInstance();
users = mRealm.where(User.class).findAllAsync();
users.addChangeListener(new RealmChangeListener<RealmResults<User>>() {
@Override
public void onChange(RealmResults<User> element) {
element= element.sort("id");
List<User> datas=mRealm.copyFromRealm(element);
String str = "";
for (int i = 0; i <datas.size(); i++) {
User user = datas.get( i);
str = str + user.toString();
}
tvShowResult.setText("查询所有数据：\n" + str);
}
});
}
@Override
protected void onDestroy() {
super.onDestroy();
if (addTask != null && !addTask.isCancelled()){
addTask.cancel();
}
if (deleteTask != null && !deleteTask.isCancelled()){
deleteTask.cancel();
}
if (updateTask != null && !updateTask.isCancelled()){
updateTask.cancel();
}
if( users != null){
users.removeChangeListeners();
}
}
}
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