Android提供了创建和是用sqlite数据库的API。sqliteDatabase代表一个数据库对象,提供了操作数据库的一些方法。
要求:
使用sqlite数据库,将某条新闻(包含标题时间内容)插入到数据库中。
实现:
sqliteOpenHelper类是sqliteDatabase一个辅助类。这个类主要生成一 个数据库,并对数据库的版本进行管理。当在程序当中调用这个类的方法getWritableDatabase()或者 getReadableDatabase()方法的时候,如果当时没有数据,那么Android系统就会自动生成一个数据库。
package com.example.hades.toutiao;
import android.content.Context;
import android.database.sqlite.sqliteDatabase;
import android.database.sqlite.sqliteOpenHelper;
import android.util.Log;
/** * Created by hades on 2017/6/17. */
public class NewsListDB extends sqliteOpenHelper {
public NewsListDB(Context context,String name,sqliteDatabase.CursorFactory factory,int version) {
super(context,name,factory,version);
}
public void onCreate(sqliteDatabase db) {
String sql = "create table if not exists list(_id integer primary key autoincrement,title text,desc text,content text,pubdate text,img text)";
Log.i("Tag","create Database");
db.execsql(sql);
}
public void onUpgrade(sqliteDatabase db,int oldVersion,int newVersion) {
Log.i("Tag","update Databases");
}
}
创建
public void Creat() {
NewsListDB listDB = new NewsListDB(context,"news.db",null,2);
sqliteDatabase db = listDB.getReadableDatabase();
Log.i("Tag","Creat");
}
public void Update() {
NewsListDB listDB = new NewsListDB(context,"Update");
}
插入
注意corsor的关闭
public void Insert(String t,String d,String c,String i,String p) {
NewsListDB listDB = new NewsListDB(context,null,2);
sqliteDatabase db = listDB.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put("title",t);
cv.put("desc",d);
cv.put("content",c);
cv.put("img",i);
cv.put("pubdate",p);
db.insertOrThrow("list",cv);
Log.i("Tag","Indert");
db.close();
}
查询
返回一个map对象
public List<Map<String,String>> Query() {
NewsListDB dbHelper = new NewsListDB(context,null,2);
sqliteDatabase db = dbHelper.getReadableDatabase();
Cursor cursor = db.query("list",new String[]{"title","desc","content","img","pubdate"},null);
List<Map<String,String>> data = new ArrayList<Map<String,String>>();
while (cursor.moveToNext()) {
Map map = new HashMap<String,String>();
map.put("news_title",cursor.getString(cursor.getColumnIndex("title")));
map.put("news_desc",cursor.getString(cursor.getColumnIndex("desc")));
map.put("news_img",cursor.getString(cursor.getColumnIndex("img")));
map.put("news_content",cursor.getString(cursor.getColumnIndex("content")));
map.put("news_pubdate",cursor.getString(cursor.getColumnIndex("pubdate")));
data.add(map);
}
cursor.close();
db.close();
return data;
}
public void Delete() {
NewsListDB listDB = new NewsListDB(context,2);
sqliteDatabase db = listDB.getReadableDatabase();
String whereClauses = "id=?";
String[] whereArgs = {String.valueOf(2)};
db.delete("stu_table",whereClauses,whereArgs);
}
完整AddLikeItem类:
package com.example.hades.toutiao;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.sqliteDatabase;
import android.database.sqlite.sqliteOpenHelper;
import android.util.Log;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/** * Created by hades on 2017/6/17. */
public class AddLikeItem {
public Context context;
public String newsTitle,newsDesc,newsContent,newsImg,newsPubDate;
public AddLikeItem(Context context) {
this.context = context;
Log.i("Tag","context2" + String.valueOf(context));
}
public void Creat() {
NewsListDB listDB = new NewsListDB(context,"Creat");
}
public void Update() {
NewsListDB listDB = new NewsListDB(context,"Update");
}
public void Insert(String t,String d,String c,String i,String p) {
NewsListDB listDB = new NewsListDB(context,2);
sqliteDatabase db = listDB.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put("title",t);
cv.put("desc",d);
cv.put("content",c);
cv.put("img",i);
cv.put("pubdate",p);
db.insertOrThrow("list",cv);
Log.i("Tag","Indert");
db.close();
}
public List<Map<String,String>> Query() {
NewsListDB dbHelper = new NewsListDB(context,new String[]{"title",null);
List<Map<String,String>> data = new ArrayList<Map<String,String>>();
while (cursor.moveToNext()) {
Map map = new HashMap<String,String>();
map.put("news_title",cursor.getString(cursor.getColumnIndex("pubdate")));
data.add(map);
}
cursor.close();
db.close();
return data;
}
public void Delete() {
NewsListDB listDB = new NewsListDB(context,whereArgs);
}
}