Android SQLite数据缓存操作

矫情吗；* 2022-04-16 02:36 240阅读 0赞

import android.content.Context;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteOpenHelper;
    
    public class DBOpenHelper extends SQLiteOpenHelper {
    
    	public DBOpenHelper(Context context) {
    		super(context, "people.db", null, 1);
    	}
    
    	@Override
    	public void onCreate(SQLiteDatabase db) {
    		//创建人员表
    		db.execSQL("drop table if exists people");
    		db.execSQL("create table people (id integer primary key autoincrement,name varchar(64),sex smallint,contact varchar(64))");
    	}
    
    	@Override
    	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    
    	}
    
    }

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 com.text.people.People;
    import com.text.people.StrUtil;
    
    public class PeopleService {
    	private DBOpenHelper dbOpenHelper;
    	private static PeopleService instance = null;
    
    	public PeopleService(Context context) {
    		this.dbOpenHelper = new DBOpenHelper(context);
    	}
    
    	public synchronized static PeopleService getInstance(Context ctx) {
    		if (null == instance) {
    			instance = new PeopleService(ctx);
    		}
    		return instance;
    	}
    	
    	//增加数据
    	public void save(People people) {
    		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
    		ContentValues values = new ContentValues();
    		values.put("name", people.getName());
    		values.put("sex", people.getSex());
    		values.put("contact", people.getContact());
    		db.insert("people", null, values);
    	}
    
    	//根据id删除日志
    	public void delete(Integer id) {
    		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
    		db.delete("people", "id=?", new String[] { id.toString() });
    	}
    
    	//删除所有数据
    	public void deleteAll() {
    		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
    		db.delete("people", "", null);
    	}
    
    	//根据id修改数据
    	public void update(People people) {
    		SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
    		ContentValues values = new ContentValues();
    		values.put("name", people.getName());
    		values.put("sex", people.getSex());
    		values.put("contact", people.getContact());
    		db.update("people", values, "id=?", new String[] { people.getId().toString() });
    	}
    
    	//根据id查询单条数据
    	public People find(Integer id) {
    		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
    		Cursor cursor = db.query("people",new String[] { "id,name,sex,contact" },
    						"id=?", new String[] { id.toString() }, null, null,
    						null, "1");
    		try {
    			if (cursor.moveToFirst()) {
    				People people = new People();
    				people.setId(id);
    				people.setName(cursor.getString(cursor.getColumnIndex("name")));
    				people.setSex(cursor.getInt(cursor.getColumnIndex("sex")));
    				people.setContact(cursor.getString(cursor.getColumnIndex("contact")));
    				return people;
    			}
    			return null;
    		} finally {
    			cursor.close();
    		}
    	}
    
    	//分页加载数据
    	public List<People> getScrollData(int currentPage, int lineSize,String whereStr) {
    		String firstResult = String.valueOf((currentPage - 1) * lineSize);
    		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
    		Cursor cursor = null;
    		try {
    			if(StrUtil.isNull(whereStr)){
    				cursor = db.query("people",
    						new String[] { "id,name,sex,contact" },
    						null, null, null, null, "id desc",
    						firstResult + "," + lineSize);
    			}else{
    				cursor = db.query("people",
    						new String[] { "id,name,sex,contact" },
    						"name like ? or contact like ?", new String[]{"%"+whereStr+"%","%"+whereStr+"%"}, null, null, "id desc",
    						firstResult + "," + lineSize);
    			}
    			List<People> peoples = new ArrayList<People>();
    			while (cursor.moveToNext()) {
    				People people = new People();
    				people.setId(cursor.getInt(cursor.getColumnIndex("id")));
    				people.setName(cursor.getString(cursor.getColumnIndex("name")));
    				people.setSex(cursor.getInt(cursor.getColumnIndex("sex")));
    				people.setContact(cursor.getString(cursor.getColumnIndex("contact")));
    				peoples.add(people);
    			}
    			return peoples;
    		} finally {
    			if(cursor!=null){
    				cursor.close();
    			}
    		}
    	}
    
    	//查询总记录数
    	public int getCount() {
    		SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
    		Cursor cursor = db.rawQuery("select count(1) from people", null);
    		try {
    			cursor.moveToFirst();
    			return cursor.getInt(0);
    		} finally {
    			cursor.close();
    		}
    	}
    }