Android中自定义ContentProvider实例

高洛峰

发布时间：2017-02-07 15:51:50

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来源于php中文网

原创

//以下为testbaidu
mainactivity如下:

package cn.testbaidu; 
import android.net.Uri; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.app.Activity; 
import android.content.ContentResolver; 
import android.content.ContentValues; 
import android.database.Cursor; 
/** 
* Demo描述: 
* 应用A(TestBaidu)调用另外一个应用(TestContentProvider) 
* 中的自定义ContentProvider,即: 
* 1 自定义ContentProvider的使用 
* 2 其它应用调用该ContentProvider 
* 
* 测试方法: 
* 1 依次测试ContentProvider的增查删改(注意该顺序) 
* 2 其它应用查询该ContentProvider的数据 
* 
*/ 
public class MainActivity extends Activity { 
private Button mAddButton; 
private Button mDeleteButton; 
private Button mUpdateButton; 
private Button mQueryButton; 
private Button mTypeButton; 
private ContentResolver mContentResolver; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.main); 
init(); 
} 
private void init() { 
mContentResolver=this.getContentResolver(); 

mAddButton=(Button) findViewById(R.id.addButton); 
mAddButton.setOnClickListener(new ClickListenerImpl()); 

mDeleteButton=(Button) findViewById(R.id.deleteButton); 
mDeleteButton.setOnClickListener(new ClickListenerImpl()); 

mUpdateButton=(Button) findViewById(R.id.updateButton); 
mUpdateButton.setOnClickListener(new ClickListenerImpl()); 

mQueryButton=(Button) findViewById(R.id.queryButton); 
mQueryButton.setOnClickListener(new ClickListenerImpl()); 

mTypeButton=(Button) findViewById(R.id.typeButton); 
mTypeButton.setOnClickListener(new ClickListenerImpl()); 

} 
private class ClickListenerImpl implements OnClickListener{ 
@Override 
public void onClick(View v) { 
switch (v.getId()) { 
case R.id.addButton: 
Person person=null; 
for (int i = 0; i < 5; i++) { 
person=new Person("xiaoming"+i, "9527"+i,(8888+i)); 
testInsert(person); 
} 
break; 
case R.id.deleteButton: 
testDelete(1); 
break; 
case R.id.updateButton: 
testUpdate(3); 
break; 
case R.id.queryButton: 
//查询表 
//queryFromContentProvider(-1); 

//查询personid=2的数据 
testQuery(2); 
break; 
case R.id.typeButton: 
testType(); 
break; 
default: 
break; 
} 

} 

} 
private void testInsert(Person person) { 
ContentValues contentValues=new ContentValues(); 
contentValues.put("name", person.getName()); 
contentValues.put("phone", person.getPhone()); 
contentValues.put("salary",person.getSalary()); 
Uri insertUri=Uri.parse("content://cn.bs.testcontentprovider/person"); 
Uri returnUri=mContentResolver.insert(insertUri, contentValues); 
System.out.println("新增数据:returnUri="+returnUri); 
} 

private void testDelete(int index){ 
Uri uri=Uri.parse("content://cn.bs.testcontentprovider/person/"+String.valueOf(index)); 
mContentResolver.delete(uri, null, null); 
} 

private void testUpdate(int index){ 
Uri uri=Uri.parse("content://cn.bs.testcontentprovider/person/"+String.valueOf(index)); 
ContentValues values=new ContentValues(); 
values.put("name", "hanmeimei"); 
values.put("phone", "1234"); 
values.put("salary", 333); 
mContentResolver.update(uri, values, null, null); 
} 
private void testQuery(int index) { 
Uri uri=null; 
if (index<=0) { 
//查询表 
uri=Uri.parse("content://cn.bs.testcontentprovider/person"); 
} else { 
//按照id查询某条数据 
uri=Uri.parse("content://cn.bs.testcontentprovider/person/"+String.valueOf(index)); 
} 

//对应上面的:查询表 
//Cursor cursor= mContentResolver.query(uri, null, null, null, null); 

//对应上面的:查询personid=2的数据 
//注意:因为name是varchar字段的,所以应该写作"name='xiaoming1'" 
// 若写成"name=xiaoming1"查询时会报错 
Cursor cursor= mContentResolver.query(uri, null, "name='xiaoming1'", null, null); 

while(cursor.moveToNext()){ 
int personid=cursor.getInt(cursor.getColumnIndex("personid")); 
String name=cursor.getString(cursor.getColumnIndex("name")); 
String phone=cursor.getString(cursor.getColumnIndex("phone")); 
int salary=cursor.getInt(cursor.getColumnIndex("salary")); 
System.out.println("查询得到:personid=" + personid+",name="+name+",phone="+phone+",salary="+salary); 
} 
cursor.close(); 
} 

private void testType(){ 
Uri dirUri=Uri.parse("content://cn.bs.testcontentprovider/person"); 
String dirType=mContentResolver.getType(dirUri); 
System.out.println("dirType:"+dirType); 

Uri itemUri=Uri.parse("content://cn.bs.testcontentprovider/person/3"); 
String itemType=mContentResolver.getType(itemUri); 
System.out.println("itemType:"+itemType); 
} 
}

Person如下:

package cn.testbaidu; 
public class Person { 
private Integer id; 
private String name; 
private String phone; 
private Integer salary; 
public Person(String name, String phone,Integer salary) { 
this.name = name; 
this.phone = phone; 
this.salary=salary; 
} 
public Person(Integer id, String name, String phone,Integer salary) { 
this.id = id; 
this.name = name; 
this.phone = phone; 
this.salary=salary; 
} 
public Integer getId() { 
return id; 
} 
public void setId(Integer id) { 
this.id = id; 
} 
public String getName() { 
return name; 
} 
public void setName(String name) { 
this.name = name; 
} 
public String getPhone() { 
return phone; 
} 
public void setPhone(String phone) { 
this.phone = phone; 
} 
public Integer getSalary() { 
return salary; 
} 
public void setSalary(Integer salary) { 
this.salary = salary; 
} 
@Override 
public String toString() { 
return "Person [id=" + id + ", name=" + name + ", phone=" + phone+ ", salary=" + salary + "]"; 
} 



}

main.xml如下:

//以下为TestContentProvider
MainActivity如下:

package cn.testcontentprovider; 
import android.app.Activity; 
import android.os.Bundle; 
public class MainActivity extends Activity { 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.main); 
} 
}

ContentProviderTest如下:

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package cn.testcontentprovider; 
import android.content.ContentProvider; 
import android.content.ContentUris; 
import android.content.ContentValues; 
import android.content.UriMatcher; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.net.Uri; 
/** 
* 注意事项: 
* 在AndroidManifest.xml中注册ContentProvider时的属性 
* android:exported="true"表示允许其他应用访问. 
* 这样TestBaidu这个应用才可以访问该处的ContentProvider 
*/ 
public class ContentProviderTest extends ContentProvider { 
private DBOpenHelper dbOpenHelper; 
private UriMatcher URI_MATCHER; 
private static final int PERSONS = 0; 
private static final int PERSON = 1; 

@Override 
public boolean onCreate() { 
initUriMatcher(); 
dbOpenHelper=new DBOpenHelper(getContext()); 
return true; 
} 
//初始化UriMatcher 
private void initUriMatcher(){ 
URI_MATCHER=new UriMatcher(UriMatcher.NO_MATCH); 
//表示返回所有的person,其中PERSONS为该特定Uri的标识码 
URI_MATCHER.addURI("cn.bs.testcontentprovider","person", PERSONS); 
//表示返回某一个person,其中PERSON为该特定Uri的标识码 
URI_MATCHER.addURI("cn.bs.testcontentprovider","person/#", PERSON); 
} 
/** 
* 插入操作: 
* 插入操作只有一种可能:向一张表中插入 
* 返回结果为新增记录对应的Uri 
* 方法db.insert()返回结果为新增记录对应的主键值 
*/ 
@Override 
public Uri insert(Uri uri, ContentValues values) { 
SQLiteDatabase db=dbOpenHelper.getWritableDatabase(); 
switch (URI_MATCHER.match(uri)) { 
case PERSONS: 
long rowid=db.insert("person", "name,phone,salary", values); 
return ContentUris.withAppendedId(uri, rowid); 
default: 
throw new IllegalArgumentException("unknown uri"+uri.toString()); 
} 
} 

/** 
* 更新操作: 
* 更新操作有两种可能:更新一张表或者更新某条数据 
* 在更新某条数据时原理类似于查询某条数据,见下. 
*/ 
@Override 
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { 
SQLiteDatabase db=dbOpenHelper.getWritableDatabase(); 
int updataNum=0; 
switch (URI_MATCHER.match(uri)) { 
//更新表 
case PERSONS: 
updataNum=db.update("person", values, selection, selectionArgs); 
break; 
//按照id更新某条数据 
case PERSON: 
long id=ContentUris.parseId(uri); 
String where="personid="+id; 
if(selection!=null&&!"".equals(selection.trim())){ 
where=selection+" and "+where; 
} 
updataNum=db.update("person", values, where, selectionArgs); 
break; 
default: 
throw new IllegalArgumentException("unknown uri"+uri.toString()); 
} 
return updataNum; 
} 

/** 
* 删除操作: 
* 删除操作有两种可能:删除一张表或者删除某条数据 
* 在删除某条数据时原理类似于查询某条数据,见下. 
*/ 
@Override 
public int delete(Uri uri, String selection, String[] selectionArgs) { 
SQLiteDatabase db=dbOpenHelper.getWritableDatabase(); 
int deletedNum=0; 
switch (URI_MATCHER.match(uri)) { 
//删除表 
case PERSONS: 
deletedNum=db.delete("person", selection, selectionArgs); 
break; 
//按照id删除某条数据 
case PERSON: 
long id=ContentUris.parseId(uri); 
String where="personid="+id; 
if(selection!=null&&!"".equals(selection.trim())){ 
where=selection+" and "+where; 
} 
deletedNum=db.delete("person", where, selectionArgs); 
break; 
default: 
throw new IllegalArgumentException("unknown uri"+uri.toString()); 
} 
return deletedNum; 
} 
/** 
* 查询操作: 
* 查询操作有两种可能:查询一张表或者查询某条数据 
* 注意事项: 
* 在查询某条数据时要注意--因为此处是按照personid来查询 
* 某条数据,但是同时可能还有其他限制.例如: 
* 要求personid为2且name为xiaoming1 
* 所以在查询时分为两步: 
* 第一步: 
* 解析出personid放入where查询条件 
* 第二部: 
* 判断是否有其他限制(如name),若有则将其 
* 组拼到where查询条件. 
* 详细代码见下. 
*/ 
@Override 
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) { 
SQLiteDatabase db=dbOpenHelper.getWritableDatabase(); 
Cursor cursor; 
switch (URI_MATCHER.match(uri)) { 
//查询表 
case PERSONS: 
cursor=db.query("person", projection, selection, selectionArgs, null, null, sortOrder); 
break; 
//按照id查询某条数据 
case PERSON: 
//第一步: 
long id=ContentUris.parseId(uri); 
String where="personid="+id; 
//第二步: 
if(selection!=null&&!"".equals(selection.trim())){ 
where=selection+" and "+where; 
} 
cursor=db.query("person", projection, where, selectionArgs, null, null, sortOrder); 
break; 
default: 
throw new IllegalArgumentException("unknown uri"+uri.toString()); 
} 
return cursor; 
} 

/** 
* 返回当前Uri所代表的数据的MIME类型. 
* 如果该Uri对应的数据可能包含多条记录,那么返回 
* 字符串应该以"vnd.android.cursor.dir/"开头 
* 如果该Uri对应的数据只包含一条记录,那么返回 
* 字符串应该以"vnd.android.cursor.item/"开头 
*/ 
@Override 
public String getType(Uri uri) { 
switch (URI_MATCHER.match(uri)) { 
case PERSONS: 
return "vnd.android.cursor.dir/persons"; 
case PERSON: 
return "vnd.android.cursor.item/person"; 
default: 
throw new IllegalArgumentException("unknown uri"+uri.toString()); 
} 
} 
}

DBOpenHelper如下:

package cn.testcontentprovider; 
import android.content.Context; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 
public class DBOpenHelper extends SQLiteOpenHelper { 
public DBOpenHelper(Context context) { 
super(context, "contentprovidertest.db", null, 1); 
} 
@Override 
public void onCreate(SQLiteDatabase db) { 
db.execSQL("create table person(personid integer primary key autoincrement,name varchar(20),phone varchar(12),salary Integer(12))"); 
} 
//当数据库版本号发生变化时调用该方法 
@Override 
public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) { 
//db.execSQL("ALTER TABLE person ADD phone varchar(12) NULL"); 
//db.execSQL("ALTER TABLE person ADD salary Integer NULL"); 
} 
}

AndroidManifest.xml如下:

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