public class Network {
//除了判斷是否有網絡,還寫工具方法判斷網絡爲什麼類型 2G、3G、4G、wifi此處忽略
public static boolean checkNetworkState(Context context) {
//得到網絡信息
ConnectivityManager manager = (ConnectivityManager)
context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo info = manager.getActiveNetworkInfo();
if (info != null && info.isAvailable()) {
//當前的網絡是連接的
return true;
} else {
return false;
}
}
}
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.INTERNET"/>
public class MySqliteOpenHelper extends SQLiteOpenHelper{
//數據庫名稱
private static final String name = "girl.db";
//數據庫版本
private static final int version = 1;
public static final String tableNmae = "girls";
public MySqliteOpenHelper(Context context) {
//第三個參數CursorFactory指定在執行查詢時獲得一個遊標實例的工廠類,設置爲null,代表使用系統默認的工廠類
super(context, name, null, version);
}
//用於初次使用軟件時生成數據庫表
@Override
public void onCreate(SQLiteDatabase db) {
/**
* 圖片的所以屬性
* title : 清純氣質韓國美女沙灘寫真
* picUrl : http://t1.du114.com/uploads/151201/10-1512011521415N.jpg
* description : 114美女
* ctime : 2016-03-06 14:11
* url : http://www.du114.com/qingchun/66307.html
*/
//執行SQL語句 創建表 此處注意table後的空格 不然語句就成了tablegirls而報錯
db.execSQL("create table " + tableNmae + "(id integer primary key autoincrement,title text," +
"picUrl text,description text,ctime text,url text)");
}
//用於升級軟件時更新數據庫表結構
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
public class GirlImageDao {
MySqliteOpenHelper mHelper;
public GirlImageDao(Context context) {
mHelper = new MySqliteOpenHelper(context);
}
//向數據庫中添加數據 即NewslistBean對象
public void addGirl(GirlsBean.ShowapiResBodyBean.NewslistBean bean) {
//Android提供了一個名爲SQLiteDatabase的類,該類封裝了一些操作數據庫的API,
//該類可以對數據進行添加(Create)、查詢(Retrieve)、更新(Update)和刪除(Delete)操作(簡稱爲CRUD)
SQLiteDatabase db = mHelper.getReadableDatabase();
ContentValues values = new ContentValues();
//存入圖片的Url地址
values.put("title", bean.getTitle());
values.put("picUrl", bean.getPicUrl());
values.put("description", bean.getDescription());
values.put("ctime", bean.getCtime());
values.put("url", bean.getUrl());
//向表中插入數據
db.insert(MySqliteOpenHelper.tableNmae, null, values);
db.close();
}
//for循環遍歷girl集合,將每個圖片地址挨個插入數據庫
public void addGirlList(List<GirlsBean.ShowapiResBodyBean.NewslistBean> list) {
for (GirlsBean.ShowapiResBodyBean.NewslistBean bean : list) {
addGirl(bean);
}
}
//查詢SQLite取出數據存入集合
public List<GirlsBean.ShowapiResBodyBean.NewslistBean> queryAllGirls() {
List<GirlsBean.ShowapiResBodyBean.NewslistBean> list = new ArrayList<>();
SQLiteDatabase db = mHelper.getReadableDatabase();
//Cursor是結果集遊標,用於對結果集進行隨機訪問,Cursor與JDBC中的ResultSet作用很相似。
Cursor cursor = db.query(MySqliteOpenHelper.tableNmae,null,null,null,null,null,null);
//moveToNext()方法可以將遊標從當前行移到下一行,如果移過了結果集的最後一行,返回結果爲false,否則爲true
while (cursor.moveToNext()) {
GirlsBean.ShowapiResBodyBean.NewslistBean bean =
new GirlsBean.ShowapiResBodyBean.NewslistBean();
//通過key 得到圖片地址值value
bean.setTitle(cursor.getString(cursor.getColumnIndex("title")));
bean.setPicUrl(cursor.getString(cursor.getColumnIndex("picUrl")));
bean.setDescription(cursor.getString(cursor.getColumnIndex("description")));
bean.setCtime(cursor.getString(cursor.getColumnIndex("ctime")));
bean.setUrl(cursor.getString(cursor.getColumnIndex("url")));
//將NewslistBean對象加入集合
list.add(bean);
}
return list;
}
}
@Override
public void onFinish(GirlsBean data) {
// //得到適配器
// mAdapter = new MyAdapter(this,data.getShowapi_res_body().getNewslist());
// //設置適配器
// mRecyclerView.setAdapter(mAdapter);
// //RecyclerView設置Item的點擊事件
// mAdapter.setOnItemClickListener(new MyAdapter.OnItemClickListener() {
//
// @Override
// public void onItemClick(String data) {
// //跳轉顯示詳細圖片的Activity
// Intent intent = new Intent(MainActivity.this, ImageShowActivity.class);
// intent.putExtra("data",data);
// startActivity(intent);
// }
// });
//存儲數據
GirlImageDao dao = new GirlImageDao(this);
dao.addGirlList(data.getShowapi_res_body().getNewslist());
}
//是否聯網
boolean isNetwork;
isNetwork = Network.checkNetworkState(this);
//判斷是否聯網,選擇數據的加載方式
if (isNetwork) {
//如果有網絡,調用getGirlList方法請求數據 1數據請求時的頁面
mRequest.getGirlList(this,1);
} else {
//沒有網絡則加載數據庫的數據
GirlImageDao dao = new GirlImageDao(this);
List<GirlsBean.ShowapiResBodyBean.NewslistBean> list = dao.queryAllGirls();
if (list.size() == 0) {
//集合數據爲0則第一次進入也未聯網
Toast.makeText(this,"網絡連接失敗",Toast.LENGTH_SHORT).show();
} else {
//數據庫有數據時候
mAdapter = new MyAdapter(this,list);
mRecyclerView.setAdapter(mAdapter);
}
}
3.3當無網絡時進入app,然後又開啓網絡,此時app應該自動加載圖片,並改變前面isNetwork的值,因此需要監聽網絡變化
public class NetworkChangeReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
//再次判斷有無網絡
isNetwork = Network.checkNetworkState(MainActivity.this);
//如果有網絡
if (isNetwork) {
Toast.makeText(context,"已連接網絡",Toast.LENGTH_SHORT).show();
//如果有網絡,調用getGirlList方法請求數據 1數據請求時的頁面
mRequest.getGirlList(MainActivity.this,1);
}else {
Toast.makeText(context,"已斷開網絡",Toast.LENGTH_SHORT).show();
}
}
}
NetworkChangeReceiver networkChangeReceiver;
//註冊網絡變化廣播接收器
public void registerNetworkChangeReceiver() {
IntentFilter intentFilter = new IntentFilter();
//廣播的動作類型
intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
networkChangeReceiver = new NetworkChangeReceiver();
//註冊
registerReceiver(networkChangeReceiver,intentFilter);
}
//動態註冊的廣播接收器都要取消
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(networkChangeReceiver);
}
<receiver android:name=".activity.MainActivity$NetworkChangeReceiver">
<intent-filter>
<!-- 監聽的動作類型,這裏是網絡連接狀態-->
<action android:name="android.net.conn.CONNECTIVITY_CHANGE"/>
</intent-filter>
</receiver>