大家在Android项目中或多或少的都会使用数据库，为了提高我们的开发效率，当然少不了数据库ORM框架了，尤其是某些数据库操作特别频繁的app；本篇博客将详细介绍ORMLite的简易用法。
下面开始介绍ORMLite的入门用法~
1、下载 ORMLite Jar
首先去ORMLite官网下载jar包，对于Android为：ormlite-android-5.0.jar 和 ormlite-core-5.0.jar ；
ps:访问不了的朋友，文章末尾会把jar、源码、doc与本篇博客例子一起打包提供给大家下载。
2、配置Bean类
有了jar,我们直接新建一个项目为：OrmliteDemo，然后把jar拷贝到libs下。
然后新建一个包：com.my.bean专门用于存放项目中的Bean，首先新建一个Usera.Java
Users:
1 package com.my.bean;
2
3 import com.j256.ormlite.field.DatabaseField;
4 import com.j256.ormlite.table.DatabaseTable;
5
6
7
8
9 @DatabaseTable(tableName="tb_users")
10 public class Users {
11 @DatabaseField(generatedId=true)
12 private int id;
13 @DatabaseField(columnName="name")
14 private String name;
15 @DatabaseField(columnName="desc")
16 private String desc;
17 public int getId() {
18 return id;
19 }
20 public void setId(int id) {
21 this.id = id;
22 }
23 public String getName() {
24 return name;
25 }
26 public void setName(String name) {
27 this.name = name;
28 }
29 public String getDesc() {
30 return desc;
31 }
32 public void setDesc(String desc) {
33 this.desc = desc;
34 }
35 public Users( String name, String desc) {
36 super();
37 this.name = name;
38 this.desc = desc;
39 }
40 public Users() {
41 super();
42 // TODO Auto-generated constructor stub
43 }
44
45
46
47 }
首先在User类上添加@DatabaseTable(tableName = "tb_user")，标明这是数据库中的一张表，标明为tb_users
然后分别在属性上添加@DatabaseField(columnName = "name") ，columnName的值为该字段在数据中的列名
@DatabaseField(generatedId = true) ，generatedId 表示id为主键且自动生成
3、编写DAO类
原生的数据库操作，需要继承SQLiteOpenHelper，这里我们需要继承OrmLiteSqliteOpenHelper
DatabaseHelper:
1 package com.my.db;
2
3 import java.sql.SQLException;
4
5 import android.content.Context;
6 import android.database.sqlite.SQLiteDatabase;
7
8 import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper;
9 import com.j256.ormlite.dao.Dao;
10 import com.j256.ormlite.support.ConnectionSource;
11 import com.j256.ormlite.table.TableUtils;
12 import com.my.bean.Users;
13
14
15 public class DatabaseHelper extends OrmLiteSqliteOpenHelper{
16 private static final String TABLE_NAME = "users.db";
17 /**
18 * usersDao，每张表对应一个
19 */
20 private Dao<Users,Integer> usersDao ;
21
22 private static DatabaseHelper instance;
23 public DatabaseHelper(Context context) {
24 super(context, TABLE_NAME, null, 1);
25 // TODO Auto-generated constructor stub
26 }
27
28 @Override
29 public void onCreate(SQLiteDatabase arg0, ConnectionSource arg1) {
30 // TODO Auto-generated method stub
31 try{
32 TableUtils.createTable(arg1, Users.class);
33 }catch(Exception e){
34 e.printStackTrace();
35 }
36 }
37
38 @Override
39 public void onUpgrade(SQLiteDatabase arg0, ConnectionSource arg1, int arg2,
40 int arg3) {
41 try
42 {
43 TableUtils.dropTable(connectionSource, Users.class, true);
44 onCreate(arg0, connectionSource);
45 } catch (SQLException e)
46 {
47 e.printStackTrace();
48 }
49
50 }
51 /**
52 * 单例获取该Helper
53 */
54 public static synchronized DatabaseHelper getHelper(Context context){
55 if(instance == null){
56 synchronized (DatabaseHelper.class) {
57 if(instance == null){
58 instance = new DatabaseHelper(context);
59 }
60 }
61 }
62 return instance;
63 }
64
65 /**
66 * 获得userDao
67 * @throws SQLException
68 */
69 public Dao<Users,Integer> getUsersDao() throws SQLException{
70 if(usersDao == null){
71 usersDao = getDao(Users.class);
72 }
73 return usersDao;
74 }
75
76
77 /**
78 * 释放资源
79 */
80
81 @Override
82 public void close() {
83 // TODO Auto-generated method stub
84 super.close();
85 usersDao = null;
86 }
87 }
这里我们需要继承OrmLiteSqliteOpenHelper，其实就是间接继承了SQLiteOpenHelper
然后需要实现两个方法：
1、onCreate(SQLiteDatabase database,ConnectionSource connectionSource)
创建表，我们直接使用ormlite提供的TableUtils.createTable(connectionSource, User.class);进行创建~
2、onUpgrade(SQLiteDatabase database, ConnectionSource connectionSource, int oldVersion, int newVersion)
更新表，使用ormlite提供的TableUtils.dropTable(connectionSource, User.class, true);进行删除操作~
删除完成后，别忘了，创建操作：onCreate(database, connectionSource);
然后使用单例公布出一个创建实例的方法，getHelper用于获取我们的help实例；
4、显示在Activity
MainActivity:
package com.example.ormlitedemo;
import java.util.List;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TableLayout;
import android.widget.TableRow;
import android.widget.TableRow.LayoutParams;
import android.widget.TextView;
import com.j256.ormlite.dao.Dao;
import com.my.bean.Users;
import com.my.db.DatabaseHelper;
public class MainActivity extends Activity {
private Dao<Users,Integer> usersDao;
private Context context;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
context = this;
//新建一个表格布局
TableLayout tblay = new TableLayout(this);
//给该Activity设置布局
setContentView(tblay,new TableLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
//插入数据
init();
try{
//取出数据
List<Users> users = getList();
//遍历集合
for (Users u : users) {
//创建一行
TableRow tr = new TableRow(this);
//新建文本视图
TextView v1 = new TextView(this);
TextView v2 = new TextView(this);
TextView v3 = new TextView(this);
v1.setText(u.getId()+"");
v2.setText(u.getName());
v3.setText(u.getDesc());
//把文本视图添加到TableRow中
tr.addView(v1,new TableRow.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, 1));
tr.addView(v2,new TableRow.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, 1));
tr.addView(v3,new TableRow.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, 1));
//把TableRow添加到TableLayout中
tblay.addView(tr);
}
}catch(Exception e){
e.printStackTrace();
}
}
//插入数据
public void init(){
DatabaseHelper helper = DatabaseHelper.getHelper(context);
try{
Users u1 = new Users("zhy","2b铅笔");
usersDao = helper.getUsersDao();
usersDao.create(u1);
u1 = new Users("zhy2", "2b铅笔");
usersDao.create(u1);
u1 = new Users("zhy3", "2b铅笔");
usersDao.create(u1);
u1 = new Users("zhy4", "2b铅笔");
usersDao.create(u1);
u1 = new Users("zhy5", "2b铅笔");
usersDao.create(u1);
u1 = new Users("zhy6", "2b铅笔");
usersDao.create(u1);
}catch(Exception e){
e.printStackTrace();
}
}
//查询所有操作
public List<Users> getList(){
DatabaseHelper helper = DatabaseHelper.getHelper(context);
List<Users> users = null;
try{
users = helper.getUsersDao().queryForAll();
}catch(Exception e){
e.printStackTrace();
}
return users;
}
//删除操作
public void DeleteUser(){
DatabaseHelper helper = DatabaseHelper.getHelper(context);
try{
helper.getUsersDao().deleteById(2);
}catch(Exception e){
e.printStackTrace();
}
}
//更新操作
public void UpdateUser(){
DatabaseHelper helper = DatabaseHelper.getHelper(context);
try{
Users u1 = new Users("lisi", "4b铅笔");
u1.setId(3);
helper.getUsersDao().update(u1);
}catch(Exception e){
e.printStackTrace();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
运行结果如下：
好了，Ormlite的简单操作就说这里了。。。。希望对大家有用，不喜勿喷
时间： 2024-07-29 12:44:23