Inessence, cursors iterate over result sets and provide access to data one row at a time.

first,We’ll want simple model objects,second,we need create table class with static methods and OpenSqliteHelper to create our database.third,a simpleinterface andDAOs for ourmodel objects.last,create a data manager layer to wrap aroundthose DAOs.

Designing a data access layer:

design table relations:

In general, if youneed to share your data with other applications you must create a ContentProvider.if you don’t need to share data, it’s usually simpler to use a
database directly.if we want touse a ContentProvider to expose our tables later, must have an _id column,which is the primary key.e

now the src code is:

create Model objects

ModelBase class:

[html] view plain copy

1. /TheModelBaseclass,whichbothMovieandCategoryextend,containsonlyalongid.
2. publicclassModelBase{
3. protectedlongid;
4. publiclonggetId(){
5. returnthis.id;
6. }
7. publicvoidsetId(longid){
8. this.id=id;
9. }
10. @Override
11. publicStringtoString(){
12. return"ModelBase[id="+this.id+"]";
13. }
14. @Override
15. publicinthashCode(){
16. finalintprime=31;
17. intresult=1;
18. result=prime*result+(int)(this.id^(this.id>>>32));
19. returnresult;
20. }
22. @Override
23. publicbooleanequals(Objectobj){
24. if(this==obj){
25. returntrue;
26. }
27. if(obj==null){
28. returnfalse;
29. }
30. if(!(objinstanceofModelBase)){
31. returnfalse;
32. }
33. ModelBaseother=(ModelBase)obj;
34. if(this.id!=other.id){
35. returnfalse;
36. }
37. returntrue;
38. }
39. }

Movie model: [html] view plain copy

1. publicclassMovieextendsModelBase{
2. privateStringproviderId;
3. privateStringname;
4. privateintyear;
5. privatedoublerating;
6. privateStringurl;
7. privateStringhomepage;
8. privateStringtrailer;
9. privateStringtagline;
10. privateStringthumbUrl;
11. privateStringimageUrl;
12. privateSet<Category>categories;
14. //note,inthereal-worldmakingthesemodelbeansimmutablewouldbeabetterapproach
15. //(thatistosay,notmakingthemJavaBeans,butmakignimmutablemodelclasseswithBuilder)
17. publicMovie(){
18. this.categories=newLinkedHashSet<Category>();
19. }
21. publicStringgetProviderId(){
22. returnthis.providerId;
23. }
25. publicvoidsetProviderId(StringproviderId){
26. this.providerId=providerId;
27. }
29. publicStringgetName(){
30. returnthis.name;
31. }
33. publicvoidsetName(Stringname){
34. this.name=name;
35. }
37. publicintgetYear(){
38. returnthis.year;
39. }
41. publicvoidsetYear(intyear){
42. this.year=year;
43. }
45. publicdoublegetRating(){
46. returnthis.rating;
47. }
49. publicvoidsetRating(doublerating){
50. this.rating=rating;
51. }
53. publicStringgetUrl(){
54. returnthis.url;
55. }
57. publicvoidsetUrl(Stringurl){
58. this.url=url;
59. }
61. publicStringgetHomepage(){
62. returnthis.homepage;
63. }
65. publicvoidsetHomepage(Stringhomepage){
66. this.homepage=homepage;
67. }
69. publicStringgetTrailer(){
70. returnthis.trailer;
71. }
73. publicvoidsetTrailer(Stringtrailer){
74. this.trailer=trailer;
75. }
77. publicStringgetTagline(){
78. returnthis.tagline;
79. }
81. publicvoidsetTagline(Stringtagline){
82. this.tagline=tagline;
83. }
85. publicStringgetThumbUrl(){
86. returnthis.thumbUrl;
87. }
89. publicvoidsetThumbUrl(StringthumbUrl){
90. this.thumbUrl=thumbUrl;
91. }
93. publicStringgetImageUrl(){
94. returnthis.imageUrl;
95. }
97. publicvoidsetImageUrl(StringimageUrl){
98. this.imageUrl=imageUrl;
99. }
101. publicSet<Category>getCategories(){
102. returnthis.categories;
103. }
105. publicvoidsetCategories(Set<Category>categories){
106. this.categories=categories;
107. }
109. @Override
110. publicStringtoString(){
111. return"Movie[categories="+this.categories+",homepage="+this.homepage+",name="+this.name
112. +",providerId="+this.providerId+",rating="+this.rating+",tagline="+this.tagline
113. +",thumbUrl="+this.thumbUrl+",imageUrl="+this.imageUrl+",trailer="+this.trailer+",url="
114. +this.url+",year="+this.year+"]";
115. }
117. @Override
118. publicinthashCode(){
119. finalintprime=31;
120. intresult=super.hashCode();
121. result=prime*result+((this.categories==null)?0:this.categories.hashCode());
122. result=prime*result+((this.homepage==null)?0:this.homepage.hashCode());
123. //uppernamesohashCodeisconsistentwithequals(equalsignorescase)
124. result=prime*result+((this.name==null)?0:this.name.toUpperCase().hashCode());
125. result=prime*result+((this.providerId==null)?0:this.providerId.hashCode());
126. longtemp;
127. temp=Double.doubleToLongBits(this.rating);
128. result=prime*result+(int)(temp^(temp>>>32));
129. result=prime*result+((this.tagline==null)?0:this.tagline.hashCode());
130. result=prime*result+((this.thumbUrl==null)?0:this.thumbUrl.hashCode());
131. result=prime*result+((this.imageUrl==null)?0:this.imageUrl.hashCode());
132. result=prime*result+((this.trailer==null)?0:this.trailer.hashCode());
133. result=prime*result+((this.url==null)?0:this.url.hashCode());
134. result=prime*result+this.year;
135. returnresult;
136. }
138. @Override
139. publicbooleanequals(Objectobj){
140. if(this==obj){
141. returntrue;
142. }
143. if(!super.equals(obj)){
144. returnfalse;
145. }
146. if(!(objinstanceofMovie)){
147. returnfalse;
148. }
149. Movieother=(Movie)obj;
150. if(this.categories==null){
151. if(other.categories!=null){
152. returnfalse;
153. }
154. }elseif(!this.categories.equals(other.categories)){
155. returnfalse;
156. }
157. if(this.homepage==null){
158. if(other.homepage!=null){
159. returnfalse;
160. }
161. }elseif(!this.homepage.equals(other.homepage)){
162. returnfalse;
163. }
164. if(this.name==null){
165. if(other.name!=null){
166. returnfalse;
167. //namecheckignorescase
168. }
169. }elseif(!this.name.equalsIgnoreCase(other.name)){
170. returnfalse;
171. }
172. if(this.providerId==null){
173. if(other.providerId!=null){
174. returnfalse;
175. }
176. }elseif(!this.providerId.equals(other.providerId)){
177. returnfalse;
178. }
179. if(Double.doubleToLongBits(this.rating)!=Double.doubleToLongBits(other.rating)){
180. returnfalse;
181. }
182. if(this.tagline==null){
183. if(other.tagline!=null){
184. returnfalse;
185. }
186. }elseif(!this.tagline.equals(other.tagline)){
187. returnfalse;
188. }
189. if(this.thumbUrl==null){
190. if(other.thumbUrl!=null){
191. returnfalse;
192. }
193. }elseif(!this.thumbUrl.equals(other.thumbUrl)){
194. returnfalse;
195. }
196. if(this.imageUrl==null){
197. if(other.imageUrl!=null){
198. returnfalse;
199. }
200. }elseif(!this.imageUrl.equals(other.imageUrl)){
201. returnfalse;
202. }
203. if(this.trailer==null){
204. if(other.trailer!=null){
205. returnfalse;
206. }
207. }elseif(!this.trailer.equals(other.trailer)){
208. returnfalse;
209. }
210. if(this.url==null){
211. if(other.url!=null){
212. returnfalse;
213. }
214. }elseif(!this.url.equals(other.url)){
215. returnfalse;
216. }
217. if(this.year!=other.year){
218. returnfalse;
219. }
220. returntrue;
221. }
222. }

Category model: [html] view plain copy

1. publicclassCategoryextendsModelBaseimplementsComparable<Category>{
2. //NOTEinreal-worldandroidappyoumightwantaCategoryFactory
3. //orfactorymethodhere,tocutdownonnumberofobjectscreated
4. privateStringname;
5. publicCategory(){
6. }
8. publicCategory(longid,Stringname){
9. this.id=id;
10. this.name=name;
11. }
13. publicStringgetName(){
14. returnthis.name;
15. }
17. publicvoidsetName(Stringname){
18. this.name=name;
19. }
21. @Override
22. publicStringtoString(){
23. returnthis.name;
24. }
26. @Override
27. publicintcompareTo(Categoryanother){
28. if(another==null){
29. return-1;
30. }
31. if(this.name==null){
32. return1;
33. }
34. returnthis.name.compareTo(another.name);
35. }
37. @Override
38. publicinthashCode(){
39. finalintprime=31;
40. intresult=super.hashCode();
41. //uppernamesohashCodeisconsistentwithequals(equalsignorescase)
42. result=prime*result+((this.name==null)?0:this.name.toUpperCase().hashCode());
43. returnresult;
44. }
46. @Override
47. publicbooleanequals(Objectobj){
48. if(this==obj){
49. returntrue;
50. }
51. if(!super.equals(obj)){
52. returnfalse;
53. }
54. if(!(objinstanceofCategory)){
55. returnfalse;
56. }
57. Categoryother=(Category)obj;
58. if(this.name==null){
59. if(other.name!=null){
60. returnfalse;
61. //namecheckignorescase
62. }
63. }elseif(!this.name.equalsIgnoreCase(other.name)){
64. returnfalse;
65. }
66. returntrue;
67. }
68. }

predefine Constant class:Constants、DataConstants: [html] view plain copy

1. publicclassConstants{
2. publicstaticfinalStringLOG_TAG="MyMovies";
3. privateConstants(){
4. }
5. }

[html] view plain copy

1. publicclassDataConstants{
2. privatestaticfinalStringAPP_PACKAGE_NAME="example.mymoviesdatabases";
3. privatestaticfinalStringEXTERNAL_DATA_DIR_NAME="mymoviesdata";
4. publicstaticfinalStringEXTERNAL_DATA_PATH=
5. Environment.getExternalStorageDirectory()+"/"+DataConstants.EXTERNAL_DATA_DIR_NAME;
7. publicstaticfinalStringDATABASE_NAME="mymovies.db";
8. publicstaticfinalStringDATABASE_PATH=
9. Environment.getDataDirectory()+"/data/"+DataConstants.APP_PACKAGE_NAME+"/databases/"
10. +DataConstants.DATABASE_NAME;
12. privateDataConstants(){
13. }
14. }

MovieTable table class:

The MovieTable class with static methods and inner class MovieColumns.

[html] view plain copy

1. publicfinalclassMovieTable{
2. publicstaticfinalStringTABLE_NAME="movie";
3. //BaseColumnsisprovidedbyAndroid,anditdefinesthe_idcolumn
4. publicstaticclassMovieColumnsimplementsBaseColumns{
5. publicstaticfinalStringHOMEPAGE="homepage";
6. publicstaticfinalStringNAME="movie_name";
7. publicstaticfinalStringRATING="rating";
8. publicstaticfinalStringTAGLINE="tagline";
9. publicstaticfinalStringTHUMB_URL="thumb_url";
10. publicstaticfinalStringIMAGE_URL="image_url";
11. publicstaticfinalStringTRAILER="trailer";
12. publicstaticfinalStringURL="url";
13. publicstaticfinalStringYEAR="year";
14. }
16. publicstaticvoidonCreate(SQLiteDatabasedb){
17. StringBuildersb=newStringBuilder();
18. //movietable
19. sb.append("CREATETABLE"+MovieTable.TABLE_NAME+"(");
20. sb.append(BaseColumns._ID+"INTEGERPRIMARYKEY,");
21. sb.append(MovieColumns.HOMEPAGE+"TEXT,");
22. sb.append(MovieColumns.NAME+"TEXTUNIQUENOTNULL,");
23. //movienamesaren'tunique,butforsimplificationweconstrain
24. sb.append(MovieColumns.RATING+"INTEGER,");
25. sb.append(MovieColumns.TAGLINE+"TEXT,");
26. sb.append(MovieColumns.THUMB_URL+"TEXT,");
27. sb.append(MovieColumns.IMAGE_URL+"TEXT,");
28. sb.append(MovieColumns.TRAILER+"TEXT,");
29. sb.append(MovieColumns.URL+"TEXT,");
30. sb.append(MovieColumns.YEAR+"INTEGER");
31. sb.append(");");
32. db.execSQL(sb.toString());
33. }
34. publicstaticvoidonUpgrade(SQLiteDatabasedb,intoldVersion,intnewVersion){
35. db.execSQL("DROPTABLEIFEXISTS"+MovieTable.TABLE_NAME);
36. MovieTable.onCreate(db);
37. }
38. }

CategoryTable table class,

with static methods and inner class CategoryColumns:

[html] view plain copy

1. publicclassCategoryTable{
2. publicstaticfinalStringTABLE_NAME="category";
3. publicstaticclassCategoryColumnsimplementsBaseColumns{
4. publicstaticfinalStringNAME="name";
5. }
7. publicstaticvoidonCreate(SQLiteDatabasedb){
8. StringBuildersb=newStringBuilder();
9. //categorytable
10. sb.append("CREATETABLE"+CategoryTable.TABLE_NAME+"(");
11. sb.append(BaseColumns._ID+"INTEGERPRIMARYKEY,");
12. sb.append(CategoryColumns.NAME+"TEXTUNIQUENOTNULL");
13. sb.append(");");
14. db.execSQL(sb.toString());
15. }
17. publicstaticvoidonUpgrade(SQLiteDatabasedb,intoldVersion,intnewVersion){
18. db.execSQL("DROPTABLEIFEXISTS"+CategoryTable.TABLE_NAME);
19. CategoryTable.onCreate(db);
20. }
21. }

MovieCategoryTable table class

The MovieCategoryTable class showing the declaration of foreign key references
[html] view plain copy

1. publicclassMovieCategoryTable{
2. publicstaticfinalStringTABLE_NAME="movie_category";
3. publicstaticclassMovieCategoryColumns{
4. publicstaticfinalStringMOVIE_ID="movie_id";
5. publicstaticfinalStringCATEGORY_ID="category_id";
6. }
8. publicstaticvoidonCreate(SQLiteDatabasedb){
9. StringBuildersb=newStringBuilder();
11. //movie_categorymappingtable
12. sb.append("CREATETABLE"+MovieCategoryTable.TABLE_NAME+"(");
13. sb.append(MovieCategoryColumns.MOVIE_ID+"INTEGERNOTNULL,");
14. sb.append(MovieCategoryColumns.CATEGORY_ID+"INTEGERNOTNULL,");
16. sb.append("FOREIGNKEY("+MovieCategoryColumns.MOVIE_ID+")REFERENCES"+MovieTable.TABLE_NAME+"("
17. +BaseColumns._ID+"),");
18. sb.append("FOREIGNKEY("+MovieCategoryColumns.CATEGORY_ID+")REFERENCES"+CategoryTable.TABLE_NAME+"("
19. +BaseColumns._ID+"),");
20. sb.append("PRIMARYKEY("+MovieCategoryColumns.MOVIE_ID+","+MovieCategoryColumns.CATEGORY_ID+")");
21. sb.append(");");
22. db.execSQL(sb.toString());
23. }
25. publicstaticvoidonUpgrade(SQLiteDatabasedb,intoldVersion,intnewVersion){
26. db.execSQL("DROPTABLEIFEXISTS"+MovieCategoryTable.TABLE_NAME);
27. MovieCategoryTable.onCreate(db);
28. }
29. }

last,The SQLiteOpenHelper used for creating and updating databases.

we need to somehow tell Android tobuild those tables,This is done by extending SQLiteOpenHelper.

[html] view plain copy

1. publicclassOpenHelperextendsSQLiteOpenHelper{
3. privatestaticfinalintDATABASE_VERSION=1;
4. privateContextcontext;
5. publicOpenHelper(finalContextcontext){
6. super(context,DataConstants.DATABASE_NAME,null,DATABASE_VERSION);
7. this.context=context;
8. }
9. publicvoidonOpen(finalSQLiteDatabasedb){
10. super.onOpen(db);
11. if(!db.isReadOnly()){
12. //versionsofSQLiteolderthan3.6.19don'tsupportforeignkeys
13. //makesureforeignkeysupportisturnedonifit'sthere
14. db.execSQL("PRAGMAforeign_keys=ON;");
15. //thenwechecktomakesurethey'reon
16. Cursorc=db.rawQuery("PRAGMAforeign_keys",null);
17. if(c.moveToFirst()){
18. intresult=c.getInt(0);
19. Log.i(Constants.LOG_TAG,"SQLiteforeignkeysupport(1ison,0isoff):"+result);
20. }else{
21. Log.i(Constants.LOG_TAG,"SQLiteforeignkeysupportNOTAVAILABLE");
22. }
23. if(!c.isClosed()){
24. c.close();
25. }
26. }
27. }
29. @Override
30. publicvoidonCreate(finalSQLiteDatabasedb){
31. //TODOAuto-generatedmethodstub
32. Log.i(Constants.LOG_TAG,"DataHelper.OpenHelperonCreatecreatingdatabase"+DataConstants.DATABASE_NAME);
34. CategoryTable.onCreate(db);
35. //populateinitialcategories(oneway,thereareseveral,thisworksokforsmalldataset)
36. CategoryDaocategoryDao=newCategoryDao(db);
37. String[]categories=context.getResources().getStringArray(R.array.tmdb_categories);
38. for(Stringcat:categories){
39. categoryDao.save(newCategory(0,cat));
40. }
41. MovieTable.onCreate(db);
42. MovieCategoryTable.onCreate(db);
43. }
45. @Override
46. publicvoidonUpgrade(finalSQLiteDatabasedb,finalintoldVersion,finalintnewVersion){
47. //TODOAuto-generatedmethodstub
48. Log.i(Constants.LOG_TAG,"SQLiteOpenHelperonUpgrade-oldVersion:"+oldVersion+"newVersion:"
49. +newVersion);
51. MovieCategoryTable.onUpgrade(db,oldVersion,newVersion);
52. MovieTable.onUpgrade(db,oldVersion,newVersion);
53. CategoryTable.onUpgrade(db,oldVersion,newVersion);
54. }
56. }

Each table object has a static method for onCreate and onUpgrade that’s called from OpenHelper’s methods.

To supply initial data of Category,we do this:

create arrays.xml

[html] view plain copy

1. <?xmlversion="1.0"encoding="utf-8"?>
2. <resources>
3. <!--UsedinView/Spinner1.java-->
4. <string-arrayname="tmdb_categories">
5. <item>Action</item>
6. <item>Adventure</item>
7. <item>Animation</item>
8. <item>Comedy</item>
9. <item>Crime</item>
10. <item>Disaster</item>
11. <item>Documentary</item>
12. <item>Drama</item>
13. <item>Eastern</item>
14. <item>Erotic</item>
15. <item>Family</item>
16. <item>FanFilm</item>
17. <item>Fantasy</item>
18. <item>FilmNoir</item>
19. <item>History</item>
20. <item>Holiday</item>
21. <item>Horror</item>
22. <item>Indie</item>
23. <item>Music</item>
24. <item>Musical</item>
25. <item>Mystery</item>
26. <item>NeoNoir</item>
27. <item>RoadMovie</item>
28. <item>Romance</item>
29. <item>ScienceFiction</item>
30. <item>Short</item>
31. <item>Sport</item>
32. <item>Suspense</item>
33. <item>Thriller</item>
34. <item>War</item>
35. <item>Western</item>
36. </string-array>
37. </resources>

in the SqliteOpenHelper class onCreate method: [html] view plain copy

1. //populateinitialcategories(oneway,thereareseveral,thisworksokforsmalldataset)
2. CategoryDaocategoryDao=newCategoryDao(db);
3. String[]categories=context.getResources().getStringArray(R.array.tmdb_categories);
4. for(Stringcat:categories){
5. categoryDao.save(newCategory(0,cat));
6. }

Forsmall amounts of data this works fine.
for large volumes of data,you can create your SQLite db file ahead of time (each SQLite database is stored as asingle file).At runtime each application database is stored in a file at the /data/data/<packagename>/databases/ internal storage location.

database:

Once we have a SQLiteOpenHelper, we can use it from anywhere in our application tocreate a SQLiteDatabase object. The SQLiteDatabase object is the keystone of
Android SQLite database operations. This is where we’ll create connections and performdata operations such as select, update, insert, and delete.

here’s an example of using our OpenHelper to obtaina SQLiteDatabase reference:

SQLiteOpenHelper openHelper = new OpenHelper(this.context);
SQLiteDatabase db = openHelper.getWritableDatabase();

The getWritableDatabase method of SQLiteOpenHelper will call onCreate the firsttime it’s called, and thereafter will call onOpen.

We have model objects for working with the data in our application’s Java code andtable objects to keep the details for each table separate from one another. We also
have a SQLiteOpenHelper implementation that can be used to create and update ourdatabase, and to provide references to the SQLiteDatabase objects we’ll later use to

store and retrieve data

原blog:

http://blog.csdn.net/kaixinbingju/article/details/8468178

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