greenDaoMaster的学习研究

最近一直在研究一个第三方的开源框架，greenDaoMaster是一个移动开发的ORM框架，由于网上一直查不到使用资料，所以自己摸索总结下用法。

首先需要新建一个JAVA项目用来自动生成文件。需要导入greendao-generator-1.3.0.jar和freemarker.jar到项目中

示例代码如下：

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1. /*
2. *Copyright(C)2011MarkusJunginger,greenrobot(http://greenrobot.de)
3. *
4. *LicensedundertheApacheLicense,Version2.0(the"License");
5. *youmaynotusethisfileexceptincompliancewiththeLicense.
6. *YoumayobtainacopyoftheLicenseat
7. *
8. *http://www.apache.org/licenses/LICENSE-2.0
9. *
10. *Unlessrequiredbyapplicablelaworagreedtoinwriting,software
11. *distributedundertheLicenseisdistributedonan"ASIS"BASIS,
12. *WITHOUTWARRANTIESORCONDITIONSOFANYKIND,eitherexpressorimplied.
13. *SeetheLicenseforthespecificlanguagegoverningpermissionsand
14. *limitationsundertheLicense.
15. */
16. packagede.greenrobot.daogenerator.gentest;
18. importde.greenrobot.daogenerator.DaoGenerator;
19. importde.greenrobot.daogenerator.Entity;
20. importde.greenrobot.daogenerator.Property;
21. importde.greenrobot.daogenerator.Schema;
22. importde.greenrobot.daogenerator.ToMany;
24. /**
25. *GeneratesentitiesandDAOsfortheexampleprojectDaoExample.
26. *
27. *RunitasaJavaapplication(notAndroid).
28. *
29. *@authorMarkus
30. */
31. publicclassExampleDaoGenerator{
33. publicstaticvoidmain(String[]args)throwsException{
35. Schemaschema=newSchema(3,"de.greenrobot.daoexample");
37. addNote(schema);
38. addCustomerOrder(schema);
40. newDaoGenerator().generateAll(schema,"../DaoExample/src-gen");
41. }
43. privatestaticvoidaddNote(Schemaschema){
44. Entitynote=schema.addEntity("Note");
45. note.addIdProperty();
46. note.addStringProperty("text").notNull();
47. note.addStringProperty("comment");
48. note.addDateProperty("date");
49. }
51. privatestaticvoidaddCustomerOrder(Schemaschema){
52. Entitycustomer=schema.addEntity("Customer");
53. customer.addIdProperty();
54. customer.addStringProperty("name").notNull();
56. Entityorder=schema.addEntity("Order");
57. order.setTableName("ORDERS");//"ORDER"isareservedkeyword
58. order.addIdProperty();
59. PropertyorderDate=order.addDateProperty("date").getProperty();
60. PropertycustomerId=order.addLongProperty("customerId").notNull().getProperty();
61. order.addToOne(customer,customerId);
63. ToManycustomerToOrders=customer.addToMany(order,customerId);
64. customerToOrders.setName("orders");
65. customerToOrders.orderAsc(orderDate);
66. }
68. }

来分析这段代码：

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1. Schemaschema=newSchema(3,"de.greenrobot.daoexample");

Schema对象接受2个参数，第一个参数是DB的版本号，通过更新版本号来更新数据库。第二个参数是自动生成代码的包路径。包路径系统自动生成

在来看这段代码

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1. Entitynote=schema.addEntity("Note");
2. note.addIdProperty();
3. note.addStringProperty("text").notNull();
4. note.addStringProperty("comment");
5. note.addDateProperty("date");

Entity表示一个实体可以对应成数据库中的表

系统自动会以传入的参数作为表的名字，这里表名就是NOTE

当然也可以自己设置表的名字，像这样：

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1. order.setTableName("ORDERS");

接下来是一些字段参数设置。

如果想ID自动增长可以像这样：

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1. order.addIdProperty().autoincrement();

再来看这一段：

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1. newDaoGenerator().generateAll(schema,"../DaoExample/src-gen");

第一个参数是Schema对象，第二个参数是希望自动生成的代码对应的项目路径。

试了下src-gen这个文件夹必须手动创建,这里路径如果错了会抛出异常。

好了先别慌运行这段程序。新建一个Android项目名字是DaoExample，和刚才的JAVA项目保持在同一个文件夹下。

接着就可以运行刚才的JAVA程序，会看到src-gen下面自动生成了8个文件，3个实体对象，3个dao，1个DaoMaster,

1个DaoSession

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1. greenDAOGenerator
2. Copyright2011-2013MarkusJunginger,greenrobot.de.LicensedunderGPLV3.
3. ThisprogramcomeswithABSOLUTELYNOWARRANTY
4. Processingschemaversion3...
5. WrittenD:\androidworkspace\OpenSource\greenDAO-master\DaoExample\src-gen\de\greenrobot\daoexample\NoteDao.java
6. WrittenD:\androidworkspace\OpenSource\greenDAO-master\DaoExample\src-gen\de\greenrobot\daoexample\Note.java
7. WrittenD:\androidworkspace\OpenSource\greenDAO-master\DaoExample\src-gen\de\greenrobot\daoexample\CustomerDao.java
8. WrittenD:\androidworkspace\OpenSource\greenDAO-master\DaoExample\src-gen\de\greenrobot\daoexample\Customer.java
9. WrittenD:\androidworkspace\OpenSource\greenDAO-master\DaoExample\src-gen\de\greenrobot\daoexample\OrderDao.java
10. WrittenD:\androidworkspace\OpenSource\greenDAO-master\DaoExample\src-gen\de\greenrobot\daoexample\Order.java
11. WrittenD:\androidworkspace\OpenSource\greenDAO-master\DaoExample\src-gen\de\greenrobot\daoexample\DaoMaster.java
12. WrittenD:\androidworkspace\OpenSource\greenDAO-master\DaoExample\src-gen\de\greenrobot\daoexample\DaoSession.java
13. Processed3entitiesin7743ms

可以看到DaoMaster中封装了SQLiteDatabase和SQLiteOpenHelper

来看看如何使用GreenDao实现CRUD

如下代码实现插入一个Note对象：

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1. DevOpenHelperhelper=newDaoMaster.DevOpenHelper(this,"notes-db",null);
2. db=helper.getWritableDatabase();
3. daoMaster=newDaoMaster(db);
4. daoSession=daoMaster.newSession();
5. noteDao=daoSession.getNoteDao();
6. Notenote=newNote(null,noteText,comment,newDate());
7. noteDao.insert(note);

代码变得如此简单。

官方推荐将取得DaoMaster对象的方法放到Application层这样避免多次创建生成Session对象。

感觉这个框架和Web的Hibernate有异曲同工之妙。

这里列出自己实际开发中的代码方便记忆：

首先是在Application层实现得到DaoMaster和DaoSession的方法：

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1. publicclassBaseApplicationextendsApplication{
3. privatestaticBaseApplicationmInstance;
4. privatestaticDaoMasterdaoMaster;
5. privatestaticDaoSessiondaoSession;
7. @Override
8. publicvoidonCreate(){
9. super.onCreate();
10. if(mInstance==null)
11. mInstance=this;
12. }
14. /**
15. *取得DaoMaster
16. *
17. *@paramcontext
18. *@return
19. */
20. publicstaticDaoMastergetDaoMaster(Contextcontext){
21. if(daoMaster==null){
22. OpenHelperhelper=newDaoMaster.DevOpenHelper(context,Constants.DB_NAME,null);
23. daoMaster=newDaoMaster(helper.getWritableDatabase());
24. }
25. returndaoMaster;
26. }
28. /**
29. *取得DaoSession
30. *
31. *@paramcontext
32. *@return
33. */
34. publicstaticDaoSessiongetDaoSession(Contextcontext){
35. if(daoSession==null){
36. if(daoMaster==null){
37. daoMaster=getDaoMaster(context);
38. }
39. daoSession=daoMaster.newSession();
40. }
41. returndaoSession;
42. }
43. }

然后写一个Db工具类：

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1. publicclassDbService{
3. privatestaticfinalStringTAG=DbService.class.getSimpleName();
4. privatestaticDbServiceinstance;
5. privatestaticContextappContext;
6. privateDaoSessionmDaoSession;
7. privateNoteDaonoteDao;
10. privateDbService(){
11. }
13. publicstaticDbServicegetInstance(Contextcontext){
14. if(instance==null){
15. instance=newDbService();
16. if(appContext==null){
17. appContext=context.getApplicationContext();
18. }
19. instance.mDaoSession=BaseApplication.getDaoSession(context);
20. instance.noteDao=instance.mDaoSession.getNoteDao();
21. }
22. returninstance;
23. }
26. publicNoteloadNote(longid){
27. returnnoteDao.load(id);
28. }
30. publicList<Note>loadAllNote(){
31. returnnoteDao.loadAll();
32. }
34. /**
35. *querylistwithwhereclause
36. *ex:begin_date_time>=?ANDend_date_time<=?
37. *@paramwherewhereclause,include'where'word
38. *@paramparamsqueryparameters
39. *@return
40. */
42. publicList<Note>queryNote(Stringwhere,String...params){
43. returnnoteDao.queryRaw(where,params);
44. }
47. /**
48. *insertorupdatenote
49. *@paramnote
50. *@returninsertorupdatenoteid
51. */
52. publiclongsaveNote(Notenote){
53. returnnoteDao.insertOrReplace(note);
54. }
57. /**
58. *insertorupdatenoteListusetransaction
59. *@paramlist
60. */
61. publicvoidsaveNoteLists(finalList<Note>list){
62. if(list==null||list.isEmpty()){
63. return;
64. }
65. noteDao.getSession().runInTx(newRunnable(){
66. @Override
67. publicvoidrun(){
68. for(inti=0;i<list.size();i++){
69. Notenote=list.get(i);
70. noteDao.insertOrReplace(note);
71. }
72. }
73. });
75. }
77. /**
78. *deleteallnote
79. */
80. publicvoiddeleteAllNote(){
81. noteDao.deleteAll();
82. }
84. /**
85. *deletenotebyid
86. *@paramid
87. */
88. publicvoiddeleteNote(longid){
89. noteDao.deleteByKey(id);
90. Log.i(TAG,"delete");
91. }
93. publicvoiddeleteNote(Notenote){
94. noteDao.delete(note);
95. }
97. }

DB常量：

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1. publicclassConstants{
2. publicstaticfinalStringDB_NAME="note_db";
3. }

Note实体类：

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1. //THISCODEISGENERATEDBYgreenDAO,DONOTEDIT.Enable"keep"sectionsifyouwanttoedit.
2. /**
3. *Entitymappedtotablenote.
4. */
5. publicclassNote{
7. privateLongid;
8. /**Not-nullvalue.*/
9. privateStringtitle;
10. /**Not-nullvalue.*/
11. privateStringcontent;
12. privatejava.util.DatecreateDate;
14. publicNote(){
15. }
17. publicNote(Longid){
18. this.id=id;
19. }
21. publicNote(Longid,Stringtitle,Stringcontent,java.util.DatecreateDate){
22. this.id=id;
23. this.title=title;
24. this.content=content;
25. this.createDate=createDate;
26. }
28. publicLonggetId(){
29. returnid;
30. }
32. publicvoidsetId(Longid){
33. this.id=id;
34. }
36. /**Not-nullvalue.*/
37. publicStringgetTitle(){
38. returntitle;
39. }
41. /**Not-nullvalue;ensurethisvalueisavailablebeforeitissavedtothedatabase.*/
42. publicvoidsetTitle(Stringtitle){
43. this.title=title;
44. }
46. /**Not-nullvalue.*/
47. publicStringgetContent(){
48. returncontent;
49. }
51. /**Not-nullvalue;ensurethisvalueisavailablebeforeitissavedtothedatabase.*/
52. publicvoidsetContent(Stringcontent){
53. this.content=content;
54. }
56. publicjava.util.DategetCreateDate(){
57. returncreateDate;
58. }
60. publicvoidsetCreateDate(java.util.DatecreateDate){
61. this.createDate=createDate;
62. }
64. }
65.