contentProvider小结

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ContentProvider小结

ContentProvider，android四大组件之一，用于对外提供数据操作的接口，通常情况下，我们是结合android的SQLite数据库来对应提供数据接口的，当然，数据不一定非要来自于数据库，也可以是文件。在编写ContentProvider的时候，通常需要用到的实例对象有：Uri，UriMatcher，ContentUris，ContentResolver。

1.Uri

Uri类用于定义ContentProvider的访问路径，类似于网站的网址，Uri由三部分组成，即：content：// + authority + path，如：content://com.jackie.providers.personprovider/person，创建Uri实例的语句如下：

Uri uri = Uri.parse("content://com.jackie.providers.personprovider/person");

2.UriMatcher

UriMatcher是用匹配Uri是否符合我们定义的格式，如下：

private UriMatcher matcher;

static {

matcher = new UriMatcher(UriMatcher.NO_MATCH);

matcher.addURI(PersonUtil.AUTHORITY, "person", 1);

matcher.addURI(PersonUtil.AUTHORITY, "person/#", 2);

}

3.ContentUris

ContentUris用于操作uri，它有两个方法：withAppendedId（uri，id），parseId（uri），从方法的定义上，我们知道withAppendedId（uri，id）用往uri添加id，而parseId这是解析uri中的id。

4.ContentResolver

ContentResolver用于客户端，它用来操作ContentProvider，同样，ContentResolver提供了与ContentProvider一致的方法。

下面是一个简单的实例：

1、person实体类

public class Person {

public int id;

public String name;

public int age;

public Person() {

}

public Person(String name,int age) {

this.name = name;

this.age = age;

}

2、person对应的数据库操作

package com.jackie.util;

import java.util.ArrayList;

import java.util.List;

import android.content.ContentValues;

import android.content.Context;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

import com.jackie.domain.Person;

public class PersonDBUtil extends SQLiteOpenHelper{

public static final String TABLE_NAME = "person";

public static final int VERSION = 1;

public PersonDBUtil(Context context) {

super(context, TABLE_NAME, null, VERSION);

}

@Override

public void onCreate(SQLiteDatabase db) {

StringBuffer person_sql = new StringBuffer();

person_sql.append("create table person ( _id integer primary key autoincrement,");

person_sql.append("name varchar(30), age integer)");

db.execSQL(person_sql.toString());

}

@Override

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}

/**

* 插入person记录

* @param person

public void insertPerson(Person person){

SQLiteDatabase db = this.getWritableDatabase();

ContentValues values = new ContentValues();

values.put("name", person.name);

values.put("age", person.age);

db.insert(TABLE_NAME, null, values);

}

/**

* 获取person列表

* @return

public List<Person> getPersons() {

SQLiteDatabase db = this.getReadableDatabase();

Cursor cursor = db.query(TABLE_NAME, null, null, null, null, null, null);

List<Person> list = new ArrayList<Person>();

while(cursor.moveToNext()) {

Person person = new Person();

person.id = cursor.getInt(cursor.getColumnIndex("_id"));

person.name = cursor.getString(cursor.getColumnIndex("name"));

person.age = cursor.getInt(cursor.getColumnIndex("age"));

list.add(person);

}

return list;

}

/**

* 获取person

* @param id

* @return

public Person getPersonById(int id){

SQLiteDatabase db = this.getReadableDatabase();

Cursor cursor = db.query(TABLE_NAME, null, "_id=?", new String[]{id + ""}, null, null, null);

Person person = new Person();

while(cursor.moveToNext()) {

person.id = cursor.getInt(cursor.getColumnIndex("_id"));

person.name = cursor.getString(cursor.getColumnIndex("name"));

person.age = cursor.getInt(cursor.getColumnIndex("age"));

break;

}

return person;

}

/**

* 更新person

* @param person

public void updatePerson(Person person){

SQLiteDatabase db = this.getWritableDatabase();

ContentValues values = new ContentValues();

values.put("name", person.name);

values.put("age", person.age);

db.update(TABLE_NAME, values, "_id=?", new String[]{person.id + ""});

}

/**

* 删除person

* @param id

public void deletePersonById(int id) {

SQLiteDatabase db = this.getWritableDatabase();

db.delete(TABLE_NAME, "_id=?", new String[]{id + ""});

}

3、person工具类

package com.jackie.util;

import android.net.Uri;

public class PersonUtil {

public static final String AUTHORITY = "com.jackie.providers.personprovider";

public static final int PERSONS = 1;

public static final int PERSON = 2;

public static final String PERSON_TYPE = "vnd.android.cursor.dir/com.jackie.providers.personprovider";

public static final String PERSON_ITEM_TYPE = "vnd.android.cursor.item/com.jackie.providers.personprovider";

public static final Uri PERSON_URI = Uri.parse("content://" + AUTHORITY + "/person");

}

4、person的ContentProvider类

package com.jackie.providers;

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;

import android.text.TextUtils;

import com.jackie.util.PersonDBUtil;

import com.jackie.util.PersonUtil;

public class PersonProvider extends ContentProvider{

private static UriMatcher matcher;

private static ContentUris contentUris;

private PersonDBUtil util;

private SQLiteDatabase db;

private String tableName ;

static {

matcher = new UriMatcher(UriMatcher.NO_MATCH);

matcher.addURI(PersonUtil.AUTHORITY, "person", PersonUtil.PERSONS);

matcher.addURI(PersonUtil.AUTHORITY, "person/#", PersonUtil.PERSON);

}

@Override

public boolean onCreate() {

contentUris = new ContentUris();

util = new PersonDBUtil(this.getContext());

db = util.getWritableDatabase();

tableName = util.TABLE_NAME;

return false;

}

@Override

public int delete(Uri uri, String selection, String[] selectionArgs) {

int count = 0;

switch (matcher.match(uri)) {

case PersonUtil.PERSONS:

count = db.delete(tableName, selection, selectionArgs);

break;

case PersonUtil.PERSON:

long id = contentUris.parseId(uri);

String whereClause = "_id = " + id + (!TextUtils.isEmpty(selection)? " AND " + selection : "");

count = db.delete(tableName, whereClause, selectionArgs);

break;

default:

new IllegalArgumentException("Unknown Uri : " + uri);

}

getContext().getContentResolver().notifyChange(uri, null);

return count;

}

@Override

public String getType(Uri uri) {

switch(matcher.match(uri)){

case PersonUtil.PERSONS:

return PersonUtil.PERSON_TYPE;

case PersonUtil.PERSON:

return PersonUtil.PERSON_ITEM_TYPE;

default:

new IllegalArgumentException("Unknown Uri : " + uri);

}

return null;

}

@Override

public Uri insert(Uri uri, ContentValues values) {

long rowId;

Uri contentUri = null;

switch(matcher.match(uri)){

case PersonUtil.PERSONS:

rowId =db.insert(tableName, null, values);

if(rowId > 0) {

contentUri = ContentUris.withAppendedId(uri, rowId);

getContext().getContentResolver().notifyChange(contentUri, null);

}

break;

default:

new IllegalArgumentException("Unknown uri:" + uri);

}

return contentUri;

}

@Override

public Cursor query(Uri uri, String[] projection, String selection,

String[] selectionArgs, String sortOrder) {

Cursor cursor = null ;

switch(matcher.match(uri)) {

case PersonUtil.PERSONS:

cursor = db.query(tableName, projection, selection, selectionArgs, null, null, null);

break;

case PersonUtil.PERSON:

long id = contentUris.parseId(uri);

String whereClause = "_id=" + id + ( !TextUtils.isEmpty(selection) ? " AND " + selection : "");

cursor = db.query(tableName, projection, whereClause, selectionArgs, null, null, null);

default:

new IllegalArgumentException("Unknown uri:" + uri);

}

cursor.setNotificationUri(getContext().getContentResolver(), uri);

return cursor;

}

@Override

public int update(Uri uri, ContentValues values, String selection,

String[] selectionArgs) {

int rowId = 0;

switch(matcher.match(uri)){

case PersonUtil.PERSONS:

rowId = db.update(tableName, values, selection, selectionArgs);

break;

case PersonUtil.PERSON:

long id = ContentUris.parseId(uri);

String whereClause = "_id=" + id + ( !TextUtils.isEmpty(selection)?" AND " + selection : "");

rowId = db.update(tableName, values, whereClause, selectionArgs);

break;

default:

new IllegalArgumentException("Unknown uri : " + uri);

}

getContext().getContentResolver().notifyChange(uri, null);

return rowId;

}

5、ContentResolver

package com.jackie.contentprovider;

import android.content.ContentResolver;

import android.content.ContentValues;

import android.database.Cursor;

import android.test.AndroidTestCase;

import com.jackie.util.PersonUtil;

public class ContentResolverTest extends AndroidTestCase {

public void insert(){

ContentResolver resolver = getContext().getContentResolver();

ContentValues values = new ContentValues();

values.put("name", "aaa");

values.put("age", 12);

resolver.insert(PersonUtil.PERSON_URI, values);

}

public void query(){

ContentResolver resolver = getContext().getContentResolver();

Cursor cursor = resolver.query(PersonUtil.PERSON_URI, null, null, null, null);

while(cursor.moveToNext()) {

System.out.println("id:" + cursor.getInt(cursor.getColumnIndex("_id")) +

"\t name : " + cursor.getString(cursor.getColumnIndex("name")) +

"\t age : " + cursor.getInt(cursor.getColumnIndex("age")));

}

6、AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.jackie.contentprovider"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk

android:minSdkVersion="8"

android:targetSdkVersion="15" />

<application

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme" >

<activity

android:name=".MainActivity"

android:label="@string/title_activity_main" >

<intent-filter>

</intent-filter>

</activity>

<uses-library android:name="android.test.runner"/>

</application>

</manifest>