Android SQLite Database Tutorial
16lz
2021-01-23
表名：
列（字段）：
联系人实体类：构造方法，setters 、getters方法
File: Contact.java
package com.example.sqlitetest;public class Contact {int _id;String _name;String _phone_number;//空的构造方法public Contact() {}//构造方法public Contact(int id, String name, String phone_number) {this._id = id;this._name = name;this._phone_number = phone_number;}//构造方法public Contact(String name, String phone_number) {this._name = name;this._phone_number = phone_number;}public int getID() {return this._id;}public void setID(int id) {this._id = id;}public String getName() {return this._name;}public void setName(String name) {this._name = name;}public String getPhoneNumber() {return this._phone_number;}public void setPhoneNumber(String phone_number) {this._phone_number = phone_number;}}
数据库的创建，表的创建，增删改查操作：
DatabaseHandler.java
package com.example.sqlitetest;import java.util.ArrayList;import java.util.List;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.database.sqlite.SQLiteOpenHelper;public class DatabaseHandler extends SQLiteOpenHelper {//Database Version 数据版本private static final int DATABASE_VERSION = 1;//Database Name 数据库名private static final String DATABASE_NAME = "contactsManager";//Contacts table name 表名private static final String TABLE_CONTACTS = "contacts";//Contacts Table Columns names 字段名private static final String KEY_ID = "id";private static final String KEY_NAME = "name";private static final String KEY_PH_NUM = "phone_number";public DatabaseHandler(Context context) {super(context, DATABASE_NAME, null, DATABASE_VERSION);}// Creating Tables 创建表: CREATE TABLE table_name (column_name column_type);@Overridepublic void onCreate(SQLiteDatabase db) {String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "(" + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT," + KEY_PH_NUM + " TEXT" + ")";db.execSQL(CREATE_CONTACTS_TABLE);}// Upgrading database@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {// Drop older table if existed 如果表存在，则删除db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);// Create tables again。删除完表后，要再次创建表onCreate(db);}/* * CRUD操作。增删改查操作 *///Adding new contact 增加 void addContact(Contact contact) { SQLiteDatabase db = this.getWritableDatabase(); ContentValues values = new ContentValues(); values.put(KEY_NAME, contact.getName()); // Contact Name values.put(KEY_PH_NUM, contact.getPhoneNumber()); // Contact Phone // Inserting Row db.insert(TABLE_CONTACTS, null, values); db.close(); // Closing database connection } // Getting single contact 获取单条记录 Contact getContact(int id) { SQLiteDatabase db = this.getReadableDatabase(); Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID, KEY_NAME, KEY_PH_NUM }, KEY_ID + "=?", new String[] { String.valueOf(id) }, null, null, null, null); if (cursor != null) cursor.moveToFirst(); Contact contact = new Contact(Integer.parseInt(cursor.getString(0)), cursor.getString(1), cursor.getString(2)); return contact; } // Getting All Contacts 获取所有的联系人信息 public List<Contact> getAllContacts() { List<Contact> contactList = new ArrayList<Contact>(); // Select All Query 查询：SELECT * FROM tableName WHERE criteria String selectQuery = "SELECT * FROM " + TABLE_CONTACTS; SQLiteDatabase db = this.getWritableDatabase(); Cursor cursor = db.rawQuery(selectQuery, null); // looping through all rows and adding to list if (cursor.moveToFirst()) { do { Contact contact = new Contact(); contact.setID(Integer.parseInt(cursor.getString(0))); contact.setName(cursor.getString(1)); contact.setPhoneNumber(cursor.getString(2)); // Adding contact to list contactList.add(contact); } while (cursor.moveToNext()); } return contactList; } // Updating single contact public int updateContact(Contact contact) { SQLiteDatabase db = this.getWritableDatabase(); ContentValues values = new ContentValues(); values.put(KEY_NAME, contact.getName()); values.put(KEY_PH_NUM, contact.getPhoneNumber()); // updating row return db.update(TABLE_CONTACTS, values, KEY_ID + " = ?", new String[] { String.valueOf(contact.getID()) }); } // Deleting single contact public void deleteContact(Contact contact) { SQLiteDatabase db = this.getWritableDatabase(); db.delete(TABLE_CONTACTS, KEY_ID + " = ?", new String[] { String.valueOf(contact.getID()) }); db.close(); } // Getting contacts Count public int getContactsCount() { String countQuery = "SELECT * FROM " + TABLE_CONTACTS; SQLiteDatabase db = this.getReadableDatabase(); Cursor cursor = db.rawQuery(countQuery, null); cursor.close(); // return count return cursor.getCount(); } }
Activity:
package com.example.sqlitetest;import java.util.List;import android.os.Bundle;import android.app.Activity;import android.util.Log;import android.view.Menu;public class SQLiteActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_sqlite); DatabaseHandler db = new DatabaseHandler(this); /** * CRUD Operations 增删改查 * */ // Inserting Contacts Log.d("Insert: ", "Inserting .."); db.addContact(new Contact("yixiaohan", "9111111111")); db.addContact(new Contact("jiangge", "9122222222")); db.addContact(new Contact("xiaokai", "9533333333")); db.addContact(new Contact("xiaoweiwei", "9544444444")); // Reading all contacts Log.d("Reading: ", "Reading all contacts.."); List<Contact> contacts = db.getAllContacts(); for (Contact cn : contacts) { String log = "Id: "+cn.getID()+" ,Name: " + cn.getName() + " ,Phone: " + cn.getPhoneNumber(); Log.d("Name: ", log);// Writing Contacts to log } }}
LogCat:
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