我以json数组的形式从服务器端获得响应。我需要首先解析它们然后将这些值插入到database.I已经解析了数据。现在我需要将该数据插入数据库。我使用以下类在数据库中创建dinserting数据。：
以下是我的帮助班：
public class WineDatabaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "applicationdata";
private static String DB_PATH = "/data/data/com.emxWinwcountry./databases/";
private static final int DATABASE_VERSION = 1;
public static final String DATABASE_CREATE ="CREATE TABLE resources(KEY_TYPE text , KEY_ENCODING text , KEY_WIDTH text, KEY_HEIGHT text, KEY_DATA text ,KeyIId text)";
public static final String DATABASE_NAVIGATION_CREATE = "create table navigation (KEY text,TYPE1 text ,LINK_NAME text,DISPLAY_NAME text ,FORWARD_ICON text ,HIGHLIGHTED_ICON_WITH_TEXT text,BANNER_IMAGE text,CHILDREN text,ICON_WITHOUT_TEXT text, HIGHLIGHTED_ICON_WITHOUT_TEXT text,ICON_WITH_TEXT text)";
public WineDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Method is called during creation of the database
@Override
public void onCreate(SQLiteDatabase database) {
try{
database.execSQL(DATABASE_CREATE);
database.execSQL(DATABASE_NAVIGATION_CREATE);
}
catch (Exception e) {
System.out.println("in on creste db"+e);
}}
// Method is called during an upgrade of the database, e.g. if you increase
// the database version
@Override
public void onUpgrade(SQLiteDatabase database, int oldVersion,
int newVersion) {
Log.w(WineDatabaseHelper.class.getName(),
"Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
database.execSQL("DROP TABLE IF EXISTS todo");
onCreate(database);
}
}
以下是我的适配器类
public class WineDatabaseAdapter {
// Database fields
public static final String KEY_TYPE = "type";
public static final String KEY_ID = "_id";
public static final String KEY_WIDTH = "width";
public static final String KEY_HEIGHT = "height";
public static final String KEY_ENCODING = "encoding";
public static final String KEY_DATA = "data";
private static final String KeyIId = "iid";
private static String DATABASE_TABLE = "resources";
private static String DATABASE_TABLE_NAVIGATION = "navigation";
private Context context;
private SQLiteDatabase database;
private WineDatabaseHelper dbHelper;
public static final String DISPLAY_NAME= "display_name";
public static final String KEY="key";
public static final String TYPE1 = "type1";
public static final String LINK_NAME = "link_name";
private static final String FORWARD_ICON = "forward_icon";
private static final String HIGHLIGHTED_ICON_WITH_TEXT = "highlighted_icon_with_text";
private static final String ICON_WITHOUT_TEXT = "icon_without_text";
private static final String HIGHLIGHTED_ICON_WITHOUT_TEXT = "highlighted_icon_without_text";
private static final String Banner_Image = "banner_image";
private static final String CHILDREN= "children";
private static final String ICON_WITH_TEXT = "icon_with_text";
private SQLiteDatabase db;
private SQLiteStatement insertStmt;
private static final String INSERT = "insert into "
+ DATABASE_TABLE + "(KEY_TYPE,KEY_ENCODING,KEY_WIDTH,KEY_HEIGHT,KEY_DATA,KeyIId)"+" values (?,?,?,?,?,?)";
private static final String INSERT_NAVIGATION = "insert into "
+ DATABASE_TABLE_NAVIGATION + "(KEY,TYPE1,LINK_NAME,DISPLAY_NAME,FORWARD_ICON,HIGHLIGHTED_ICON_WITH_TEXT,ICON_WITHOUT_TEXT,HIGHLIGHTED_ICON_WITHOUT_TEXT,Banner_Image,CHILDREN,ICON_WITH_TEXT)"+" values (?,?,?,?,?,?,?,?,?,?,?)";
public WineDatabaseAdapter(Context context) {
try{
this.context = context;
WineDatabaseHelper openHelper = new WineDatabaseHelper(context);
this.db=openHelper.getWritableDatabase();
this.insertStmt=this.db.compileStatement(INSERT);
this.insertStmt=this.db.compileStatement(INSERT_NAVIGATION);
}
catch(Exception e)
{
System.out.println(e);
}
}
public long insert(String KEY_TYPE ,String KEY_ENCODING,String KEY_WIDTH,String KEY_HEIGHT,String KEY_DATA,String KeyIId){
this.insertStmt.bindString(1, KEY_TYPE);
this.insertStmt.bindString(2, KEY_ENCODING);
this.insertStmt.bindString(3, KEY_WIDTH);
this.insertStmt.bindString(4, KEY_WIDTH);
this.insertStmt.bindString(5, KEY_DATA);
this.insertStmt.bindString(6, KeyIId);
return this.insertStmt.executeInsert();
}
public long insertNavigation(String KEY ,String TYPE1,String LINK_NAME,String DISPLAY_NAME,String FORWARD_ICON,String HIGHLIGHTED_ICON_WITH_TEXT,String ICON_WITHOUT_TEXT,String HIGHLIGHTED_ICON_WITHOUT_TEXT,String Banner_Image,String CHILDREN,String ICON_WITH_TEXT ){
this.insertStmt.bindString(1, KEY);
this.insertStmt.bindString(2, TYPE1);
this.insertStmt.bindString(3, LINK_NAME);
this.insertStmt.bindString(4, DISPLAY_NAME);
this.insertStmt.bindString(5, FORWARD_ICON);
this.insertStmt.bindString(6, HIGHLIGHTED_ICON_WITH_TEXT);
this.insertStmt.bindString(7, ICON_WITHOUT_TEXT);
this.insertStmt.bindString(8, HIGHLIGHTED_ICON_WITHOUT_TEXT);
this.insertStmt.bindString(9, Banner_Image);
this.insertStmt.bindString(10, CHILDREN);
this.insertStmt.bindString(11, ICON_WITH_TEXT);
return this.insertStmt.executeInsert();
}
public Cursor fetchAllResources() {
return database.query(DATABASE_TABLE, new String[] { KEY_TYPE,
KEY_ENCODING, KEY_WIDTH, KEY_WIDTH,KEY_DATA, KeyIId}, null, null, null,
null, null);
}
public List<String> selectTable(){
List<String> list=new ArrayList<String>();
Cursor c = db.rawQuery("SELECT * FROM " +
DATABASE_TABLE , null);
if(c.moveToFirst()){
do{
list.add(c.getString(0));
}
while(c.moveToNext());
}
if(c !=null && !c.isClosed()){
c.close();
}
return list;
}
public void deleteAll(){
this.db.delete(DATABASE_TABLE, null, null);
}
public void deleteAllNavigation(){
this.db.delete(DATABASE_TABLE_NAVIGATION, null, null);
}
public List<String> selectAll(){
List<String> list=new ArrayList<String>();
Cursor cursor=this.db.query(DATABASE_TABLE, new String[]{"KEY_TYPE","KEY_ENCODING","KEY_WIDTH","KEY_HEIGHT","KEY_DATA","KeyIId"},
null, null, null, null, "KeyIId");
if(cursor.moveToFirst()){
do{
list.add(cursor.getString(0));
}
while(cursor.moveToNext());
}
if(cursor !=null && !cursor.isClosed()){
cursor.close();
}
return list;
}
public List<String> selectAllNavigation(){
List<String> list=new ArrayList<String>();
Cursor cursor=this.db.query(DATABASE_TABLE_NAVIGATION, new String[]{"KEY,TYPE1","LINK_NAME","DISPLAY_NAME","FORWARD_ICON","HIGHLIGHTED_ICON_WITH_TEXT","ICON_WITHOUT_TEXT","HIGHLIGHTED_ICON_WITHOUT_TEXT","Banner_Image","CHILDREN,ICON_WITH_TEXT"},
null, null, null, null, "Key");
if(cursor.moveToFirst()){
do{
list.add(cursor.getString(0));
}
while(cursor.moveToNext());
}
if(cursor !=null && !cursor.isClosed()){
cursor.close();
}
return list;
}
public WineDatabaseAdapter open() throws SQLException {
dbHelper = new WineDatabaseHelper(context);
database = dbHelper.getWritableDatabase();
return this;
}
public void close() {
dbHelper.close();
}
public long createNavigation(String key, String type, String link_name, String display_name,String forward_icon, String highlighted_icon_with_text, String banner_image,String highlighted_icon_without_text,String icon_without_text,String children,String icon_with_text ) {
ContentValues initialValues = createNavigationValues(key,type,link_name,display_name, forward_icon,
highlighted_icon_with_text, banner_image, highlighted_icon_without_text,banner_image,highlighted_icon_without_text,icon_without_text);
return database.insert(DATABASE_TABLE, null, initialValues);
}
public boolean updateNavigation (long rowId,String key,String type, String link_name,String display_name, String forward_icon, String highlighted_icon_with_text, String banner_image,String highlighted_icon_without_text,String icon_without_text,String children,String icon_with_text )
{ ContentValues updateValues = createNavigationValues(key, type,link_name,display_name, forward_icon,
highlighted_icon_with_text, banner_image, highlighted_icon_without_text,banner_image,highlighted_icon_without_text,icon_without_text);
return database.update(DATABASE_TABLE, updateValues, KEY_ID + "="
+ rowId, null) > 0;
}
public boolean deleteNavigation(long rowId) {
return database.delete(DATABASE_TABLE, KEY_ID + "=" + rowId, null) > 0;
}
public Cursor fetchAllNavigations() {
return database.query(DATABASE_TABLE_NAVIGATION, new String[] { KEY_ID,TYPE1,FORWARD_ICON,LINK_NAME,HIGHLIGHTED_ICON_WITH_TEXT,Banner_Image,CHILDREN,ICON_WITHOUT_TEXT,HIGHLIGHTED_ICON_WITHOUT_TEXT,ICON_WITH_TEXT}, null, null, null,
null, null);
}
public Cursor fetchNavigation(long rowId) throws SQLException {
Cursor mCursor = database.query(true, DATABASE_TABLE_NAVIGATION, new String[] { KEY_ID,TYPE1,FORWARD_ICON,LINK_NAME,HIGHLIGHTED_ICON_WITH_TEXT,Banner_Image,CHILDREN,ICON_WITHOUT_TEXT,HIGHLIGHTED_ICON_WITHOUT_TEXT,ICON_WITH_TEXT},
KEY_ID + "=" + rowId, null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
public long createTodo(String iid,String type, String encoding, String data)
{
ContentValues initialValues = createContentValues(iid,type,
encoding, data);
return database.insert(DATABASE_TABLE, null, initialValues);
}
public boolean updateTodo(long rowId,String iid, String type,
String encoding, String data ) {
ContentValues updateValues = createContentValues(iid, type,
encoding, data);
return database.update(DATABASE_TABLE, updateValues, KEY_ID + "="
+ rowId, null) > 0;
}
public boolean deleteTodo(long rowId) {
return database.delete(DATABASE_TABLE, KEY_ID + "=" + rowId, null) > 0;
}
public Cursor fetchAllTodos() {
return database.query(DATABASE_TABLE, new String[] { KEY_ID,KeyIId,
KEY_TYPE, KEY_WIDTH,KEY_HEIGHT, KEY_ENCODING, KEY_DATA }, null, null, null,
null, null);
}
public Cursor fetchTodo(long rowId) throws SQLException {
Cursor mCursor = database.query(true, DATABASE_TABLE, new String[] {
KEY_ID,KeyIId, KEY_TYPE, KEY_WIDTH, KEY_HEIGHT, KEY_ENCODING, KEY_DATA },
KEY_ID + "=" + rowId, null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
private ContentValues createContentValues( String iid,String type,
String encoding, String data) {
ContentValues values = new ContentValues();
values.put(KeyIId, iid);
values.put(KEY_TYPE, type);
values.put(KEY_ENCODING, encoding);
values.put(KEY_DATA, data);
return values;
}
private ContentValues createNavigationValues(String key,String type, String link_name,String display_name, String forward_icon, String highlighted_icon_with_text, String banner_image,String highlighted_icon_without_text,String icon_without_text,String children,String icon_with_text ) {
ContentValues values = new ContentValues();
values.put(KEY, key);
values.put(TYPE1, type);
values.put(LINK_NAME, link_name);
values.put(DISPLAY_NAME, display_name);
values.put(FORWARD_ICON, forward_icon);
values.put(HIGHLIGHTED_ICON_WITH_TEXT, highlighted_icon_with_text);
values.put(Banner_Image, banner_image);
values.put(CHILDREN, children);
values.put(ICON_WITHOUT_TEXT, icon_without_text);
values.put(HIGHLIGHTED_ICON_WITHOUT_TEXT, highlighted_icon_without_text);
values.put(ICON_WITH_TEXT, icon_with_text);
return values;
}
}
我将这些值插入到以下活动中：
for (int ii = 0; ii < resources.length(); ii++)
{
type = resources.getJSONObject(ii).getString("type").toString();
encoding = resources.getJSONObject(ii).getString("encoding").toString();
data1 = resources.getJSONObject(ii).getString("data").toString();
iid = resources.getJSONObject(ii).getString("id").toString();
try{
width=resources.getJSONObject(ii).getString("width").toString();
height=resources.getJSONObject(ii).getString("height").toString();
}
catch(Exception e){
e.printStackTrace();
}
db = new WineDatabaseAdapter(HomePageWithPhoneIsOfflineDialog.this);
db.insert(type,encoding,width,height, data1,iid);
db.fetchAllResources()
它给了我 null pointer exception on fetchAllResources() method 。相反，当我使用字符串构建器打印值时，它会打印值。
编辑：
它返回一个空数组，即没有像[]那样的任何值。是不是在数据库中插入了值？然后如何在数据库中插入值。
任何人都可以告诉我为什么会这样。 感谢
答案 0 :(得分：3)
public Cursor fetchAllResources() {
return database.query(DATABASE_TABLE, new String[] { KEY_TYPE,
KEY_ENCODING, KEY_WIDTH, KEY_WIDTH,KEY_DATA, KeyIId}, null, null, null,
null, null);
}
此处您正在使用永远不会初始化的database =＆gt;空指针异常
答案 1 :(得分：1)
您不能在适配器类中使用SQLitedatabase类的数据库对象，因为该对象将为null，因为它未初始化。
而是将fetchAllResources（）方法放在databasehelper类中，或者在使用数据库对象之前调用open（）方法。
希望它有所帮助。
答案 2 :(得分：0)
因为在创建表时，您使用了KEY_TYPE，KEY_ID等作为字段名称，这些名称按原样使用。它们不被视为变量。因此您应该将表声明为：
public static final String DATABASE_CREATE ="CREATE TABLE resources(type text,encoding text,width text,height text,data text ,iid text)";
public static final String DATABASE_NAVIGATION_CREATE = "create table navigation (key text,type1 text ,link_name text,display_name text ,forward_icon text ,highlighted_icon_with_text text,banner_image text,childer text,icon_without_text text, highlighted_icon_without_text text,icon_with_text text)";
或
public static final String DATABASE_CREATE ="CREATE TABLE resources("+WineDatabaseAdapter.KEY_TYPE+" text,"+WineDatabaseAdapter.KEY_ENCODING+" text ,"+WineDatabaseAdapter.KEY_WIDTH+" text,"+WineDatabaseAdapter.KEY_HEIGHT+" text,"+WineDatabaseAdapter.KEY_DATA+" text,"+WineDatabaseAdapter.KeyIId+" text)";
public static final String DATABASE_NAVIGATION_CREATE = "create table navigation ("+WineDatabaseAdapter.KEY+" text,"+WineDatabaseAdapter.TYPE1+" text,"+WineDatabaseAdapter.LINK_NAME+" text,"+WineDatabaseAdapter.DISPLAY_NAME+" text ,"+WineDatabaseAdapter.FORWARD_ICON+" text ,"+WineDatabaseAdapter.HIGHLIGHTED_ICON_WITH_TEXT+" text,"+WineDatabaseAdapter.BANNER_IMAGE+" text,"+WineDatabaseAdapter.CHILDREN+" text,"+WineDatabaseAdapter.ICON_WITHOUT_TEXT+" text,"+WineDatabaseAdapter.HIGHLIGHTED_ICON_WITHOUT_TEXT+" text,"+WineDatabaseAdapter.ICON_WITH_TEXT+" text)";
修改：
还要将此方法添加到WineDatabaseAdapter：
public WineDatabaseAdpater open() throws SQLException
{
dbcreator=new DatabaseCreator(context);
sqdb=dbcreator.getWritableDatabase();
return this;
}
public void close()
{
dbcreator.close();
}
使用此课程时，请使用
WineDatabaseAdapter wda=new WineDatabaseAdapter(context);
wda.open();
wda.fetchAllResources();
wda.close();