我想将 json 数据存储到数据库，它必须显示我的应用程序必须显示一些以前的数据，而无需互联网时间。为此，我想创建一个用于存储 json 数据的数据库。
这是我为 json 数据创建的数据库部分。
public class GinfyDbAdapter {
private static final String DATABASE_NAME = "ginfy.db";
private static final String DATABASE_TABLE_PROJ = "prayers";
private static final int DATABASE_VERSION = 2;
public static final String CATEGORY_COLUMN_ID = "id";
public static final String CATEGORY_COLUMN_TITLE = "title";
public static final String CATEGORY_COLUMN_CONTENT = "content";
public static final String CATEGORY_COLUMN_COUNT = "count";
private static final String TAG = "ProjectDbAdapter";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
public GinfyDbAdapter(MainActivity mainActivity) {
// TODO Auto-generated constructor stub
}
public GinfyDbAdapter GinfyDbAdapter(Context context){
mDbHelper = new DatabaseHelper(context);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void saveCategoryRecord(String id, String title, String content, String count) {
ContentValues contentValues = new ContentValues();
contentValues.put(CATEGORY_COLUMN_ID, id);
contentValues.put(CATEGORY_COLUMN_TITLE, title);
contentValues.put(CATEGORY_COLUMN_CONTENT, content);
contentValues.put(CATEGORY_COLUMN_COUNT, count);
mDb.insert(DATABASE_NAME, null, contentValues);
}
public Cursor getTimeRecordList() {
return mDb.rawQuery("select * from " + DATABASE_NAME, null);
}
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
private static final String DATABASE_CREATE_PROJ =
"create table " + DATABASE_TABLE_PROJ + " ("
+ CATEGORY_COLUMN_ID + " integer primary key autoincrement, "
+ CATEGORY_COLUMN_TITLE + " text not null, " + CATEGORY_COLUMN_CONTENT + " text not null, " + CATEGORY_COLUMN_COUNT + " integer primary key autoincrement );" ;
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL("CREATE TABLE " + DATABASE_TABLE_PROJ + "( "
+ CATEGORY_COLUMN_ID + " INTEGER PRIMARY KEY, "
+ CATEGORY_COLUMN_TITLE + " TEXT, " + CATEGORY_COLUMN_CONTENT + " TEXT, " + CATEGORY_COLUMN_COUNT + " INTEGER PRIMARY KEY )" );
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("DROP TABLE IF EXISTS"+ DATABASE_NAME);
onCreate(db);
}
}
}
这是显示 ListView 的主 Activity
public class MainActivity extends Activity implements FetchDataListener,OnClickListener{
private static final int ACTIVITY_CREATE=0;
private static final String TAG_CATEGORY = "post";
private static final String CATEGORY_COLUMN_ID = "id";
private static final String CATEGORY_COLUMN_TITLE = "title";
private static final String CATEGORY_COLUMN_CONTENT = "content";
private static final String CATEGORY_COLUMN_COUNT = "count";
private static final int Application = 0;
private ProgressDialog dialog;
ListView lv;
ListView lv1;
private List<Application> items;
private Button btnGetSelected;
private Button praycount;
public int pct;
private String stringVal;
private TextView value;
private int prayers;
private int prayerid;
EditText myFilter;
ApplicationAdapter adapter;
private GinfyDbAdapter mDbHelper;
JSONArray contacts = null;
private SimpleCursorAdapter dataAdapter;
@Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list_item);
mDbHelper=new GinfyDbAdapter(MainActivity.this);
lv1 =(ListView)findViewById(R.id.list);
lv =(ListView)findViewById(R.id.list);
ArrayList<HashMap<String, String>> contactList = new ArrayList<HashMap<String, String>>();
// Creating JSON Parser instance
//JSONParser jParser = new JSONParser();
JSONObject jsonObject = new JSONObject();
//JSONArray aJson = jsonObject.getJSONArray("post");
String url = "http://www.ginfy.com/api/v1/posts.json";
// getting JSON string from URL
JSONArray aJson = jsonObject.getJSONFromUrl(url);
try {
// Getting Array of Contacts
contacts = aJson.getJSONObject(TAG_CATEGORY);
// looping through All Contacts
for(int i = 0; i < contacts.length(); i++){
JSONObject c = contacts.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(CATEGORY_COLUMN_ID);
String title = c.getString(CATEGORY_COLUMN_TITLE);
String content = c.getString(CATEGORY_COLUMN_CONTENT);
String count = c.getString(CATEGORY_COLUMN_COUNT);
mDbHelper.saveCategoryRecord(id,title,content,count);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(CATEGORY_COLUMN_ID, id);
map.put(CATEGORY_COLUMN_TITLE, title);
map.put(CATEGORY_COLUMN_CONTENT, content);
map.put(CATEGORY_COLUMN_COUNT, count);
// adding HashList to ArrayList
contactList.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
}
btnGetSelected = (Button) findViewById(R.id.btnget);
btnGetSelected.setOnClickListener(this);
myFilter = (EditText) findViewById(R.id.myFilter);
//praycount.setOnClickListener(this);
initView();
}
private void initView(){
// show progress dialog
dialog = ProgressDialog.show(this, "", "Loading...");
String url = "http://www.ginfy.com/api/v1/posts.json";
FetchDataTask task = new FetchDataTask(this);
task.execute(url);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
MenuInflater mi = getMenuInflater();
mi.inflate(R.menu.activity_main, menu);
return true;
}
@Override
public boolean onMenuItemSelected(int featureId, MenuItem item) {
createProject();
return super.onMenuItemSelected(featureId, item);
}
private void createProject() {
Intent i = new Intent(this, AddPrayerActivity.class);
startActivityForResult(i, ACTIVITY_CREATE);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
super.onActivityResult(requestCode, resultCode, intent);
initView();
}
@Override
public void onFetchComplete(List<Application> data){
this.items = data;
// dismiss the progress dialog
if ( dialog != null )
dialog.dismiss();
// create new adapter
ApplicationAdapter adapter = new ApplicationAdapter(this, data);
/*dataAdapter adapter = new SimpleCursorAdapter(this,
R.layout.activity_row,
new String[] { CATEGORY_COLUMN_TITLE, CATEGORY_COLUMN_CONTENT, CATEGORY_COLUMN_COUNT }, new int[] {
R.id.text2, R.id.text1, R.id.count });*/
//lv.setListAdapter(adapter);
// set the adapter to list
lv.setAdapter(adapter);
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
CheckBox chk = (CheckBox) view.findViewById(R.id.checkbox);
Application bean = items.get(position);
if (bean.isSelected()) {
bean.setSelected(false);
chk.setChecked(false);
} else {
bean.setSelected(true);
chk.setChecked(true);
}
}
});
}
// Toast is here...
private void showToast(String msg) {
Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
}
@Override
public void onFetchFailure(String msg){
if ( dialog != null )
dialog.dismiss();
Toast.makeText(this, msg, Toast.LENGTH_LONG).show();
}
在使用数据库之前它也会显示在 ListView 中，现在我也想创建数据库，为此我在 mainactivity 中编写了一些代码。
Fetchdatatask.java
public class FetchDataTask extends AsyncTask<String, Void, String>
{
private final FetchDataListener listener;
private OnClickListener onClickListener;
private String msg;
public FetchDataTask(FetchDataListener listener)
{
this.listener = listener;
}
@Override
protected String doInBackground(String... params)
{
if ( params == null )
return null;
// get url from params
String url = params[0];
try
{
// create http connection
HttpClient client = new DefaultHttpClient();
HttpGet httpget = new HttpGet(url);
// connect
HttpResponse response = client.execute(httpget);
// get response
HttpEntity entity = response.getEntity();
if ( entity == null )
{
msg = "No response from server";
return null;
}
// get response content and convert it to json string
InputStream is = entity.getContent();
return streamToString(is);
}
catch ( IOException e )
{
msg = "No Network Connection";
}
return null;
}
@Override
protected void onPostExecute(String sJson)
{
if ( sJson == null )
{
if ( listener != null )
listener.onFetchFailure(msg);
return;
}
try
{
// convert json string to json object
JSONObject jsonObject = new JSONObject(sJson);
JSONArray aJson = jsonObject.getJSONArray("post");
// create apps list
List<Application> apps = new ArrayList<Application>();
for ( int i = 0; i < aJson.length(); i++ )
{
JSONObject json = aJson.getJSONObject(i);
Application app = new Application();
app.setContent(json.getString("content"));
app.setTitle(json.getString("title"));
app.setCount(Integer.parseInt(json.getString("count")));
app.setId(Integer.parseInt(json.getString("id")));
// add the app to apps list
apps.add(app);
}
//notify the activity that fetch data has been complete
if ( listener != null )
listener.onFetchComplete(apps);
}
catch ( JSONException e )
{
e.printStackTrace();
msg = "Invalid response";
if ( listener != null )
listener.onFetchFailure(msg);
return;
}
}
/**
* This function will convert response stream into json string
*
* @param is
* respons string
* @return json string
* @throws IOException
*/
public String streamToString(final InputStream is) throws IOException
{
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try
{
while ( (line = reader.readLine()) != null )
{
sb.append(line + "\n");
}
}
catch ( IOException e )
{
throw e;
}
finally
{
try
{
is.close();
}
catch ( IOException e )
{
throw e;
}
}
return sb.toString();
}
}
这个 fetchdatatask 从 json 获取并显示在 ListView 中，我希望在没有互联网时间的情况下它也必须显示在 ListView 中，因为我正在创建数据库。
你能检查一下我的代码是否正确，实际上它在主要 Activity 行 JSONArray aJson = jsonObject.getJSONFromUrl(url); 中显示错误
最佳答案
创建一个类，充当数据库类和主 Activity 之间的中间层，以将数据插入数据库，反之亦然
public class Category {
String id;
String title;
String content;
String count;
public Category(String id, String title, String content, String count) {
super();
this.id = id;
this.title = title;
this.content = content;
this.count = count;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public String getCount() {
return count;
}
public void setCount(String count) {
this.count = count;
}
}
在您进行 json 解析的主要 Activity 中，创建一个 DB 类对象并调用其中的保存记录方法，就像我在下面所做的那样
DatabaseHelper mDbHelper;
public class ABC extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.abc);
mDbHelper= new DatabaseHelper (this);
new GetSyncDataAsyncTask().execute();
}
}
private class GetDataAsyncTask extends AsyncTask<Void, Void, Boolean> {
private ProgressDialog Dialog = new ProgressDialog(ABC.this);
protected void onPreExecute() {
Dialog.setMessage("Loading.....");
Dialog.show();
}
@Override
protected void onPostExecute(Boolean result) {
super.onPostExecute(result);
Dialog.dismiss();
Intent intent = new Intent(ABC.this, XYZ.class);
startActivity(intent);
}
@Override
protected Boolean doInBackground(Void... params) {
getData();
return null;
}
}
public void getProdData() {
// getting JSON string from URL
JSONParser parser = new JSONParser();
JSONObject jsonObject = new JSONObject();
//JSONArray aJson = jsonObject.getJSONArray("post");
String url = "http://www.ginfy.com/api/v1/posts.json";
// getting JSON string from URL
JSONArray aJson = jsonObject.getJSONFromUrl(url);
try {
// Getting Array of Contacts
contacts = aJson.getJSONObject(TAG_CATEGORY);
// looping through All Contacts
for(int i = 0; i < contacts.length(); i++){
JSONObject c = contacts.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(CATEGORY_COLUMN_ID);
String title = c.getString(CATEGORY_COLUMN_TITLE);
String content = c.getString(CATEGORY_COLUMN_CONTENT);
String count = c.getString(CATEGORY_COLUMN_COUNT);
mDbHelper.saveCategoryRecord(new Category(id,title,content,count));
}
} catch (JSONException e) {
e.printStackTrace();
}
}
最后在您的数据库类中插入如下所示的值
public void saveCategoryRecord(Category category) {
String query = "insert into"+ TABLE_NAME+ values( ?, ?, ?, ?, ?, ? )";
SQLiteStatement stmt = mDb.compileStatement(query);
stmt.bindString(1, category.getId());
stmt.bindString(2, category.getTitle());
stmt.bindString(3, category.getContent());
stmt.bindString(4, category.getCount());
stmt.execute();
}
我尝试使用与您使用过的相同的东西。我认为这就是你现在有了做到这一点的概念的方式
关于java - 想要将json数据插入Sqlite数据库，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/17441031/