Android GreenDao数据库—基础详解
1.GreenDao数据库简介
greenDAO是一个对象关系映射（ORM）的框架，能够提供一个接口通过操作对象的方式去操作关系型数据库，它能够让你操作数据库时更简单、更方便。如下图所示：
官网地址：http://greenrobot.org/greendao
github：https://github.com/greenrobot/greenDAO
2.GreenDao 优点
2.1.性能高，号称Android最快的关系型数据库。
2.2.内存占用小 库文件比较小，小于100K，编译时间低，而且可以避免65K方法限制。
2.3.支持数据库加密 greendao支持SQLCipher进行数据库加密 。
2.4.简洁易用的API。
3.代码讲解
3.1.配置Gradle
根目录gradle
// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
repositories {
google()
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:3.3.2'
classpath 'org.greenrobot:greendao-gradle-plugin:3.2.2' // add plugin
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
allprojects {
repositories {
google()
jcenter()
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}
app gradle
apply plugin: 'com.android.application'
apply plugin: 'org.greenrobot.greendao' // apply plugin
android {
compileSdkVersion 28
defaultConfig {
applicationId "com.wjn.androiddbdemo"
minSdkVersion 15
targetSdkVersion 26
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
greendao {
// 版本号
schemaVersion 1
//greendao输出dao的数据库操作实体类文件夹
daoPackage 'com.wjn.androiddbdemo.greendao'
//greenDao实体类包文件夹
targetGenDir 'src/main/java'
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.support:appcompat-v7:28.0.0'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.2'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
implementation 'com.readystatesoftware.systembartint:systembartint:1.0.3'
implementation 'org.greenrobot:greendao:3.2.2' // add library
}
3.2.创建实体类
步骤
3.2.1.创建类名为People的普通类并创建所需要的属性
public class People {
private Long id;
private String name;
private String height;
private String weight;
}id 必须为Long
3.2.2.类名上@Entity
3.2.3.Make Project
稍等片刻 后实体类 变成如下
@Entity
public class People {
@Id(autoincrement = true)
private Long id;
private String name;
private String height;
private String weight;
@Generated(hash = 516943684)
public People(Long id, String name, String height, String weight) {
this.id = id;
this.name = name;
this.height = height;
this.weight = weight;
}
@Generated(hash = 1406030881)
public People() {
}
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 String getHeight() {
return this.height;
}
public void setHeight(String height) {
this.height = height;
}
public String getWeight() {
return this.weight;
}
public void setWeight(String weight) {
this.weight = weight;
}
}
注意：主键要添加autoincrement 自增
否则会报 does not have a single-column primary key 错误
设置的文件夹中会生成以下类
3.3.在Application中获取 DaoSession
public class MyApplication extends Application {
private static DaoSession daoSession;
@Override
public void onCreate() {
super.onCreate();
setupDatabase();
}
/**
* 配置数据库
*/
private void setupDatabase() {
//创建数据库shop.db 创建SQLite数据库的SQLiteOpenHelper的具体实现
DaoMaster.DevOpenHelper helper = new DaoMaster.DevOpenHelper(this, "greendaodemo.db", null);
//获取SQLiteDatabase对象
SQLiteDatabase db = helper.getReadableDatabase();
//获取数据库对象
DaoMaster daoMaster = new DaoMaster(db);
//获取dao对象管理者
daoSession = daoMaster.newSession();
}
/**
* 获取 DaoSession 外部调用
* */
public static DaoSession getDaoInstant() {
return daoSession;
}
}
3.4.Activity代码
public class GreenDaoActivity extends AppCompatActivity implements View.OnClickListener {
private TextView textView1;
private TextView textView2;
private TextView textView3;
private TextView textView4;
private TextView textView;
private String string="123456";
private Long id;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_greendao);
initView();
}
/**
* 初始化各种View
*/
private void initView() {
//根据状态栏颜色来决定 状态栏背景 用黑色还是白色 true:是否修改状态栏字体颜色
StatusBarUtil.setStatusBarMode(this, false, false, R.color.colorPrimary);
textView1 = findViewById(R.id.activity_greendao_textview1);
textView2 = findViewById(R.id.activity_greendao_textview2);
textView3 = findViewById(R.id.activity_greendao_textview3);
textView4 = findViewById(R.id.activity_greendao_textview4);
textView = findViewById(R.id.activity_greendao_textview);
textView1.setOnClickListener(this);
textView2.setOnClickListener(this);
textView3.setOnClickListener(this);
textView4.setOnClickListener(this);
id=Long.parseLong(string);
}
/**
* 各种点击事件的方法
*/
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.activity_greendao_textview1://增
insertUser();
break;
case R.id.activity_greendao_textview2://删
deleteUser();
break;
case R.id.activity_greendao_textview3://改
updateUser();
break;
case R.id.activity_greendao_textview4://查
List list=queryUserList();
StringBuilder sbBuilder = new StringBuilder();
for(int i=0;i queryUserList() {
UserInfoDao userInfoDao= MyApplication.getDaoInstant().getUserInfoDao();
QueryBuilder qb = userInfoDao.queryBuilder();
List list = qb.list();
return list;
}
}
3.5.结果
3.5.1.增——>查
3.5.2.删——>查
3.5.3.改——>查
3.6.注意
主键设置了自增后 插入是就可以不用设置id
3.6.1.插入数据
/**
* 插入一条记录
*/
public void insertUser() {
UserInfo userInfo=new UserInfo();
userInfo.setName("张三");
userInfo.setAge("29");
UserInfo userInfo1=new UserInfo();
userInfo1.setName("李四");
userInfo1.setAge("39");
UserInfo userInfo2=new UserInfo();
userInfo2.setName("旺旺");
userInfo2.setAge("19");
UserInfo userInfo3=new UserInfo();
userInfo3.setName("王伟");
userInfo3.setAge("59");
List list=new ArrayList<>();
list.add(userInfo);
list.add(userInfo1);
list.add(userInfo2);
list.add(userInfo3);
UserInfoDao userInfoDao= MyApplication.getDaoInstant().getUserInfoDao();
userInfoDao.insertInTx(list);
}
3.6.2.结果
代码链接：https://github.com/wujianning/AndroidDBDemo