文章目录
前言
ormlite看起来挺简单，其实做起来挺恼火的，昨天做了很久，但是没实现效果，就没有写博客
一、Ormlte
Ormlite全称Object Relational Mapping，是一个非常轻量级的数据库操作框架，它的底层是根据反射机制来实现的。
ormlite的使用：
新建表，借用别人的图：
增删改查：ORMLite简介和增删改查方法的使用
二、使用Ormlite
1.引入库
这个我在上一个里面写到了：安卓开发学习——day6
2.新建ContactsInfo(联系人信息表)
注意：生成空的构造方法，不然报错；生成get|set方法，方便调用
package com.example.task3.entity;
import com.j256.ormlite.field.DatabaseField;
import com.j256.ormlite.table.DatabaseTable;
//表名
@DatabaseTable(tableName = "contacts")
public class ContactsInfo {
@DatabaseField(columnName = "id", generatedId = true)
public int id; //设置主键
@DatabaseField(columnName = "contactName")
private String contactName;
@DatabaseField(columnName = "contactCompany")
private String contactCompany;
@DatabaseField(columnName = "contactTel")
private String contactTel;
public ContactsInfo() {
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getContactName() {
return contactName;
}
public void setContactName(String contactName) {
this.contactName = contactName;
}
public String getContactCompany() {
return contactCompany;
}
public void setContactCompany(String contactCompany) {
this.contactCompany = contactCompany;
}
public String getContactTel() {
return contactTel;
}
public void setContactTel(String contactTel) {
this.contactTel = contactTel;
}
}
3.新建DatabaseHelper(生成数据库结构信息)
继承继承OrmLiteSqliteOpenHelper类，重写 onCreate\onUpgrade方法
package com.example.task3.db;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import com.example.task3.entity.ContactsInfo;
import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper;
import com.j256.ormlite.dao.Dao;
import com.j256.ormlite.support.ConnectionSource;
import com.j256.ormlite.table.TableUtils;
import java.sql.SQLException;
/**
* 定义数据库的工具类，继承OrmLiteSqliteOpenHelper类，重写 onCreate\onUpgrade方法
*/
public class DatabaseHelper extends OrmLiteSqliteOpenHelper {
//定义数据库存放位置，便于以后查看
public static final String DATABASE_PATH = "mydb.db";
//定义数据库的版本号，当数据库需要升级时进行更改
public static final int DATABASE_VERSION = 1;
public DatabaseHelper(Context context) {
super(context, DATABASE_PATH, null, DATABASE_VERSION);
}
public Dao<ContactsInfo, Integer> contactsInfoDao;
public Dao<ContactsInfo, Integer> getContactsInfoDao() {
if (contactsInfoDao == null) {
try {
contactsInfoDao = getDao(ContactsInfo.class);
} catch (SQLException e) {
e.printStackTrace();
}
}
return contactsInfoDao;
}
/***
* 第一次创建数据库创建
* @param database
* @param connectionSource
*/
@Override
public void onCreate(SQLiteDatabase database, ConnectionSource connectionSource) {
try {
TableUtils.createTable(connectionSource, ContactsInfo.class);
} catch (SQLException e) {
e.printStackTrace();
}
}
/***
* 升级数据库时调用
* @param database
* @param connectionSource
* @param oldVersion
* @param newVersion
*/
@Override
public void onUpgrade(SQLiteDatabase database, ConnectionSource connectionSource, int oldVersion, int newVersion) {
if (newVersion > oldVersion) {
try {
TableUtils.dropTable(connectionSource, ContactsInfo.class, true);
TableUtils.createTableIfNotExists(connectionSource, ContactsInfo.class);
} catch (SQLException e) {
e.printStackTrace();
}
}
}
@Override
public void close() {
super.close();
if (contactsInfoDao != null) {
contactsInfoDao = null;
}
}
}
4.测试
xml只需要3个输入框和两个按钮
package com.example.task3;
import android.database.SQLException;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import com.example.task3.db.DatabaseHelper;
import com.example.task3.entity.ContactsInfo;
import com.j256.ormlite.dao.Dao;
import java.util.List;
public class TestOrmActivity extends AppCompatActivity implements View.OnClickListener {
private EditText edtName;
private EditText edtCompany;
private EditText edtTel;
private Button btnInsert;
private Button btnRead;
private DatabaseHelper dbHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test_orm);
edtName = findViewById(R.id.edt_name);
edtCompany = findViewById(R.id.edt_company);
edtTel = findViewById(R.id.edt_tel);
btnInsert = findViewById(R.id.btn_);
btnRead = findViewById(R.id.btn_read);
btnInsert.setOnClickListener(this);
btnRead.setOnClickListener(this);
}
@Override
public void onClick(View view) {
if (dbHelper==null){
dbHelper = new DatabaseHelper(TestOrmActivity.this);
}
int id = view.getId();
switch (id){
case R.id.btn_:
//插入数据
String name = edtName.getText().toString();
String company = edtCompany.getText().toString();
String tel = edtTel.getText().toString();
//获取操作表的dao对象
Dao<ContactsInfo,Integer> contactsInfoDao = dbHelper.getContactsInfoDao();
//插入对应的数据
ContactsInfo contactsInfo = new ContactsInfo();
contactsInfo.setContactName(name);
contactsInfo.setContactCompany(company);
contactsInfo.setContactTel(tel);
try {
//通过操作实体对象的形式将数据插入到表中
contactsInfoDao.createIfNotExists(contactsInfo);
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
break;
case R.id.btn_read:
//读取数据
Dao<ContactsInfo ,Integer> contactsInfoList = dbHelper.getContactsInfoDao();
try {
List<ContactsInfo> contactsInfoDataList = contactsInfoList.queryForAll();
StringBuffer strBuffer = new StringBuffer();
for(int i =0;i<contactsInfoDataList.size();i++){
strBuffer.append("第"+i+"位置的word="+contactsInfoDataList.get(i).getContactName()+"；单词的含义"+contactsInfoDataList.get(i).getContactTel()+"\n");
}
Toast.makeText(TestOrmActivity.this, strBuffer.toString(), Toast.LENGTH_SHORT).show();
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
break;
}
}
}
三、完善通讯录的关于Ormlite的功能
1.添加联系人
package com.example.task3;
import android.content.Intent;
import android.database.SQLException;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import com.example.task3.db.DatabaseHelper;
import com.example.task3.entity.ContactsInfo;
import com.j256.ormlite.dao.Dao;
public class AddActivity extends AppCompatActivity implements View.OnClickListener {
private ImageView ok;
private ImageView cancel;
private EditText edtName;
private EditText edtCompany;
private EditText edtTel;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add);
ok = findViewById(R.id.ok);
cancel = findViewById(R.id.cancel);
edtName = findViewById(R.id.edt_name);
edtCompany = findViewById(R.id.edt_company);
edtTel = findViewById(R.id.edt_tel);
ok.setOnClickListener(this);
cancel.setOnClickListener(this);
}
private DatabaseHelper dbHelper;
@Override
public void onClick(View v) {
if (dbHelper == null) {
dbHelper = new DatabaseHelper(AddActivity.this);
}
int id = v.getId();
switch (id) {
case R.id.ok:
//插入数据
String name = edtName.getText().toString();
String company = edtCompany.getText().toString();
String tel = edtTel.getText().toString();
//获取操作表的dao对象
Dao<ContactsInfo, Integer> contactsInfoDao = dbHelper.getContactsInfoDao();
//插入对应的数据
ContactsInfo contactsInfo = new ContactsInfo();
contactsInfo.setContactName(name);
contactsInfo.setContactCompany(company);
contactsInfo.setContactTel(tel);
try {
//通过操作实体对象的形式将数据插入到表中
contactsInfoDao.createIfNotExists(contactsInfo);
} catch (SQLException | java.sql.SQLException e) {
e.printStackTrace();
}
Toast.makeText(AddActivity.this, "添加" + edtName.getText().toString() + "成功"
, Toast.LENGTH_LONG).show();
Intent intent = new Intent(AddActivity.this, MainActivity.class);
startActivity(intent);
break;
case R.id.cancel:
intent = new Intent(AddActivity.this, MainActivity.class);
startActivity(intent);
break;
}
}
}
2.读取联系人
package com.example.task3;
import android.content.Intent;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import com.example.task3.db.DatabaseHelper;
import com.example.task3.entity.ContactsInfo;
import com.j256.ormlite.dao.Dao;
import java.sql.SQLException;
import java.util.List;
public class MainActivity extends AppCompatActivity{
private TextView tvAdd;
private EditText edtSo;
private ListView lvContacts;
private ImageView find;
private ContactAdapter adapter;
DatabaseHelper dbHelper = new DatabaseHelper(this);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tvAdd = findViewById(R.id.tv_add);
edtSo = findViewById(R.id.edt_find_contact);
lvContacts = findViewById(R.id.lv_contacts);
find = findViewById(R.id.find);
try {
Dao<ContactsInfo, Integer> dao = dbHelper.getDao(ContactsInfo.class);
List<ContactsInfo> contact = dao.queryBuilder().selectColumns("contactName").query();
adapter = new ContactAdapter(MainActivity.this,contact);
lvContacts.setAdapter(adapter);
} catch (SQLException e) {
e.printStackTrace();
}
edtSo.setOnEditorActionListener(new TextView.OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
String text = edtSo.getText().toString().trim();
try {
Dao<ContactsInfo, Integer> dao = dbHelper.getDao(ContactsInfo.class);
List<ContactsInfo> contact = dao.queryBuilder().where().like("contactName","%"+text+"%").query();
//初始化适配器
ContactAdapter findAdapter = new ContactAdapter(MainActivity.this, contact);
lvContacts.setAdapter(findAdapter);
} catch (SQLException e) {
e.printStackTrace();
}
return false;
}
});
tvAdd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this, AddActivity.class);
startActivity(intent);
}
});
}
}
3.查找联系人
4.效果图
遇到的问题
问题1
ormlite E/SQLiteLog: (1) no such table: contacts
解决方法：
已经创建过诸如contacts表之后,部署到手机上,此时数据库已经初始化完成.但是现在有需求又新加了一个表,此时代码都写完了,此时部署到手机上,调用新表里面的ContactInfoDao.create(bean)方法会出现no such table错误.
把原来安装的app卸载重新部署。
总结
ormlite数据库因为没有找到较为完整的教程，所以用时比较久，写的还不够完善。