Android studio結合資料庫簡單的進行展示刪除
阿新 • • 發佈：2018-11-21
xml裡面的程式碼在這裡插入程式碼片
main裡面的程式碼
<Button android:id="@+id/get_Btn" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="獲取資料" /> <ListView android:id="@+id/listView" android:layout_width="match_parent" android:layout_height="match_parent"> </ListView>
介面卡中的程式碼在這裡插入item
<TextView
android:id="@+id/list_tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
主頁面中的程式碼
import android.content.DialogInterface; import android.os.AsyncTask; import android.os.Bundle; import android.support.v7.app.AlertDialog; import android.support.v7.app.AppCompatActivity； import android.view.View; import android.widget.AdapterView; import android.widget.Button; import android.widget.ListView; import com.example.adapter.MyAdapter; import com.example.bean.MyData; import com.example.dao.MyDao; import com.example.utils.MyUtils; import com.google.gson.Gson; import java.util.ArrayList; import java.util.List; public class MainActivity extends AppCompatActivity implements View.OnClickListener { private Button get_Btn; private ListView listView； //將網址寫入 private String mUrl = "http://api.expoon.com/AppNews/getNewsList/type/1/p/1"; private List<MyData.DataBean> lists = new ArrayList<>(); private MyAdapter adapter; private MyDao dao; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); dao = new MyDao(this); initView(); adapter = new MyAdapter(this, lists); listView.setAdapter(adapter); listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, final int position, long id) { AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this); builder.setTitle("刪除"); builder.setMessage("確定刪除嗎?"); builder.setPositiveButton("確定", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { String title = adapter.getDatas().get(position).getNews_title(); int dele = dao.dele(title); //進行判斷刪除 if (dele>0){ adapter.setDatas(dao.show()); } } }); builder.setNegativeButton("取消", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); } } ); AlertDialog dialog = builder.create(); dialog.show(); } } ); } private void initView() { get_Btn = (Button) findViewById(R.id.get_Btn); listView = (ListView) findViewById(R.id.listView); get_Btn.setOnClickListener(this); } @Override public void onClick(View v) { switch (v.getId()) { case R.id.get_Btn: List<MyData.DataBean> dataBeanList = dao.show(); //進行判斷 if (dataBeanList.size() > 0) { adapter.setDatas(dataBeanList); } else { new MyTask().execute(mUrl); } break; } } class MyTask extends AsyncTask<String, Void, List<MyData.DataBean>> { @Override protected List<MyData.DataBean> doInBackground(String... strings) { //建立uri String json = MyUtils.getMyStrig(strings[0]); Gson gson = new Gson(); MyData myData = gson.fromJson(json, MyData.class); return myData.getData(); } @Override protected void onPostExecute(List<MyData.DataBean> dataBeans) { super.onPostExecute(dataBeans); adapter.setDatas(dataBeans); dao.add(dataBeans); } } }
封裝的介面卡
import android.content.Context; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.TextView; import com.example.bean.MyData; import com.example.zhoukaolianxi1.R; import java.util.List; public class MyAdapter extends BaseAdapter { private Context mContext; private List<MyData.DataBean> datas; public MyAdapter(Context mContext, List<MyData.DataBean> datas) { this.mContext = mContext; this.datas = datas; } public void setDatas(List<MyData.DataBean> datas) { this.datas = datas; //重新整理介面卡 notifyDataSetChanged(); } public List<MyData.DataBean> getDatas() { return datas; } @Override public int getCount() { return datas.size(); } @Override public Object getItem(int position) { return null; } @Override public long getItemId(int position) { return 0; } @Override public View getView(int position, View convertView, ViewGroup parent) { //宣告一個holder類 ViewHolder holder = null; //進行判斷 if (convertView == null) { holder = new ViewHolder(); convertView = View.inflate(mContext, R.layout.item, null); holder.tv_list = convertView.findViewById(R.id.list_tv); convertView.setTag(holder); } else { holder = (ViewHolder) convertView.getTag(); } holder.tv_list.setText(datas.get(position).getNews_title()); return convertView; } //holder類 class ViewHolder { TextView tv_list; } } }
這裡是bean包
import java.util.List;
public class MyData {
private int status;
private String info;
private List<DataBean> data;
public int getStatus() {
return status;
}
public void setStatus(int status) {
this.status = status;
}
public String getInfo() {
return info;
}
public void setInfo(String info) {
this.info = info;
}
public List<DataBean> getData() {
return data;
}
public void setData(List<DataBean> data) {
this.data = data;
}
public static class DataBean {
private String news_id;
private String news_title;
private String news_summary;
private String pic_url;
public String getNews_id() {
return news_id;
}
public void setNews_id(String news_id) {
this.news_id = news_id;
}
public String getNews_title() {
return news_title;
}
public void setNews_title(String news_title) {
this.news_title = news_title;
}
public String getNews_summary() {
return news_summary;
}
public void setNews_summary(String news_summary) {
this.news_summary = news_summary;
}
public String getPic_url() {
return pic_url;
}
public void setPic_url(String pic_url) {
this.pic_url = pic_url;
} }
}
helper類
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class MyHelper extends SQLiteOpenHelper {
public MyHelper(Context context) {
super(context, "mydb", null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table news (title text)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
dao層
mport android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import com.example.bean.MyData;
import java.util.ArrayList;
import java.util.List;
public class MyDao {
private SQLiteDatabase database;
public MyDao(Context mContext) {
MyHelper helper = new MyHelper(mContext);
database = helper.getWritableDatabase();
}
public List<MyData.DataBean> show() {
//建立一個集合
List<MyData.DataBean> datas = new ArrayList<MyData.DataBean>();
Cursor qu = database.query("news", null, null, null, null, null, null, null);
while (qu.moveToNext()) {
String title = qu.getString(qu.getColumnIndex("title"));
//建立一個bean包類
MyData.DataBean dataBean = new MyData.DataBean();
dataBean.setNews_title(title);
datas.add(dataBean);
}
return datas;
}
public void add(List<MyData.DataBean> datas) {
//迴圈新增
for (int i = 0; i < datas.size(); i++) {
ContentValues values = new ContentValues();
values.put("title", datas.get(i).getNews_title());
database.insert("news", null, values);
}
}
public int dele(String title) {
int i = database.delete("news", "title = ? ", new String[]{title});
return i;
}
}
我自己將解析資料的方法抽出來單獨封裝了一個工具類
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class MyUtils {
public static String getMyStrig(String mUrl) {
try {
URL url = new URL(mUrl);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
InputStream stream = connection.getInputStream();
String sb = getStr(stream);
return sb;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public static String getStr(InputStream stream) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
StringBuffer sb = new StringBuffer();
String con = "";
while ((con = reader.readLine()) != null) {
sb.append(con);
}
reader.close();
return sb.toString();
}
}