Android中使用Sqlite数据库 (二) 增删改查
定义接口
package com.example.android_db.service; import java.util.List; import java.util.Map; public interface PersonService { public boolean addPerson(Object[] params); public boolean deletePerson(Object[] params); public boolean updatePerson(Object[] params); public Map<String,String> viewPerson(String[] selectionArgs); public List<Map<String,String>> listPersonMaps(String[] selectionArgs); }
实现接口:
package com.example.android_db.dao; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import com.example.android_db.db.DbOpenHelper; import com.example.android_db.service.PersonService; public class PersonDao implements PersonService { private DbOpenHelper helper = null; public PersonDao(Context context) { // TODO Auto-generated constructor stub helper = new DbOpenHelper(context); } @Override public boolean addPerson(Object[] params) { // TODO Auto-generated method stub boolean flag = false; //实现对数据库的添加删除和修改查询的功能 SQLiteDatabase database = null; try { String sql = "insert into person(name,address,sex) values(?,?,?)"; database = helper.getWritableDatabase();//实现对数据库的写的操作 database.execSQL(sql, params); flag = true; } catch (Exception e) { // TODO: handle exception e.printStackTrace(); }finally{ if(database!=null){ database.close(); } } return flag; } @Override public boolean deletePerson(Object[] params) { // TODO Auto-generated method stub boolean flag = false; SQLiteDatabase database = null; try { String sql = "delete from person where id = ? "; database = helper.getWritableDatabase(); database.execSQL(sql, params); flag = true; } catch (Exception e) { // TODO: handle exception }finally{ if(database!=null){ database.close(); } } return flag; } @Override public boolean updatePerson(Object[] params) { // TODO Auto-generated method stub boolean flag = false; SQLiteDatabase database = null; try { String sql = "update person set name = ? ,address = ?, sex = ? where id = ? "; database = helper.getWritableDatabase(); database.execSQL(sql, params); flag = true; } catch (Exception e) { // TODO: handle exception }finally{ if(database!=null){ database.close(); } } return flag; } @Override public Map<String, String> viewPerson(String[] selectionArgs) { Map<String,String> map = new HashMap<String, String>(); SQLiteDatabase database = null; try { String sql = "select * from person where id = ? "; database = helper.getReadableDatabase(); Cursor cursor = database.rawQuery(sql, selectionArgs); //获得数据库的列的个数 int colums = cursor.getColumnCount(); while(cursor.moveToNext()){ for(int i=0;i<colums;i++){ String cols_name = cursor.getColumnName(i); String cols_value = cursor.getString(cursor.getColumnIndex(cols_name)); if(cols_value==null){ cols_value = ""; } map.put(cols_name, cols_value); } } } catch (Exception e) { // TODO: handle exception }finally{ if(database!=null){ database.close(); } } return map; } @Override public List<Map<String, String>> listPersonMaps(String[] selectionArgs) { // TODO Auto-generated method stub List<Map<String,String>> list = new ArrayList<Map<String,String>>(); String sql = "select * from person "; SQLiteDatabase database = null; try { database = helper.getReadableDatabase(); Cursor cursor = database.rawQuery(sql, selectionArgs); int colums = cursor.getColumnCount(); while(cursor.moveToNext()){ Map<String,String> map = new HashMap<String, String>(); for(int i=0;i<colums;i++){ String cols_name = cursor.getColumnName(i); String cols_value = cursor.getString(cursor.getColumnIndex(cols_name)); if(cols_value==null){ cols_value=""; } map.put(cols_name, cols_value); } list.add(map); } } catch (Exception e) { // TODO: handle exception }finally{ if(database!=null){ database.close(); } } return list; } }
实现SQLiteOpenHelper的子类
package com.example.android_db.db; import android.content.Context; import android.database.DatabaseErrorHandler; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteDatabase.CursorFactory; import android.database.sqlite.SQLiteOpenHelper; public class DbOpenHelper extends SQLiteOpenHelper { private static String name = "mydb.db";// 表示数据库的名称 private static int version = 2;// 表示数据库的版本号码 public DbOpenHelper(Context context) { super(context, name, null, version); } // 当数据库创建的时候,是第一次被执行,完成对数据库的表的创建 @Override public void onCreate(SQLiteDatabase db) { // TODO Auto-generated method stub //支持的数据类型:整型数据,字符串类型,日期类型,二进制的数据类型, String sql = "create table person(id integer primary key autoincrement,name varchar(64),address varchar(64))"; db.execSQL(sql); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { // TODO Auto-generated method stub String sql = "alter table person add sex varchar(8)"; db.execSQL(sql); } }
测试类:
package com.example.android_db.test; import java.util.List; import java.util.Map; import com.example.android_db.dao.PersonDao; import com.example.android_db.db.DbOpenHelper; import com.example.android_db.service.PersonService; import android.test.AndroidTestCase; import android.util.Log; public class MyTest extends AndroidTestCase { public MyTest() { // TODO Auto-generated constructor stub } public void createDb(){ DbOpenHelper helper = new DbOpenHelper(getContext()); helper.getWritableDatabase(); } public void insertDB(){ PersonService service = new PersonDao(getContext()); Object[] params = {"李斯","广西","女"}; boolean flag = service.addPerson(params); System.out.println("--->>"+flag); } public void deleteDB(){ PersonService service = new PersonDao(getContext()); Object[] params = {1}; boolean flag = service.deletePerson(params); System.out.println("--->>"+flag); } public void updateDB(){ PersonService service = new PersonDao(getContext()); Object[] params = {"王五","上海","不祥","3"}; service.updatePerson(params); } public void viewDB(){ PersonService service = new PersonDao(getContext()); String[] selectionArgs = {"3"}; Map<String, String> map = service.viewPerson(selectionArgs); Log.i("Test", "-->>"+map.toString()); } public void listDB(){ PersonService service = new PersonDao(getContext()); List<Map<String,String>> list = service.listPersonMaps(null); Log.i("Test", "-->>"+list.toString()); } }
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