扣丁学堂笔记第17天ContentProvider组件与Loaders

1.ContentProvider简介与准备工作











首先自定义ContentProvider类继承自ContentProvider，实现它的6个方法；

然后创建一个DatabaseAdapter类，创建一个DatabaseHelper继承自SQLiteOpenHelper，重写它的构造方法和实现2个方法

然后再DatabaseAdapter类中添加增删改查方法的代码；

然后在清单文件中注册ContentProvider





2.ContentProvider定义匹配器与添加数据

3.ContentProvider删除修改查询方法与数据类型

4.ContentProvider调用内容提供器

PersonMetaData.java

package com.example.contentprovidertest;

import android.provider.BaseColumns;

public final class PersonMetaData {

private PersonMetaData(){}
public static abstract class PersonTable implements BaseColumns{
public static final String TABLE_NAME = "table_name";
public static final String NAME = "name";
public static final String AGE = "age";
}
}

DatabaseAdapter

package com.example.contentprovidertest;

import java.util.ArrayList;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DatabaseAdapter {

private DatabaseHelper dbHelper;

public DatabaseAdapter(Context context) {
dbHelper = new DatabaseHelper(context);
}

public void save(Person person) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(PersonMetaData.PersonTable.NAME, person.getName());
values.put(PersonMetaData.PersonTable.AGE, person.getAge());
db.insert(PersonMetaData.PersonTable.TABLE_NAME, null, values);
db.close();
}

public void delete(int id){
SQLiteDatabase db = dbHelper.getWritableDatabase();
db.delete(PersonMetaData.PersonTable.TABLE_NAME, PersonMetaData.PersonTable._ID+"=?",
new String[]{String.valueOf(id)});
db.close();
}

public void update(Person person){
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(PersonMetaData.PersonTable.NAME, person.getName());
values.put(PersonMetaData.PersonTable.AGE, person.getAge());
db.update(PersonMetaData.PersonTable.TABLE_NAME, values, PersonMetaData.PersonTable._ID+"=?",
new String[]{String.valueOf(person.getId())});
db.close();
}

public ArrayList<Person> findAll(){
SQLiteDatabase db = dbHelper.getReadableDatabase();
Cursor c = db.query(PersonMetaData.PersonTable.TABLE_NAME, null, null, null, null, null, null);
ArrayList<Person> list = new ArrayList<Person>();
Person p = null;
while(c.moveToNext()){
p.setId(c.getInt(c.getColumnIndexOrThrow(PersonMetaData.PersonTable._ID)));
p.setName(c.getString(c.getColumnIndexOrThrow(PersonMetaData.PersonTable.NAME)));
p.setAge(c.getInt(c.getColumnIndexOrThrow(PersonMetaData.PersonTable.AGE)));
list.add(p);
}
c.close();
db.close();
return list;

}

public Person findById(int id){
SQLiteDatabase db = dbHelper.getReadableDatabase();
Cursor c = db.query(PersonMetaData.PersonTable.TABLE_NAME, null, PersonMetaData.PersonTable._ID+"=?", new String[]{String.valueOf(id)}, null, null, null);
Person p = null;
if(c.moveToNext()){
p.setId(c.getInt(c.getColumnIndexOrThrow(PersonMetaData.PersonTable._ID)));
p.setName(c.getString(c.getColumnIndexOrThrow(PersonMetaData.PersonTable.NAME)));
p.setAge(c.getInt(c.getColumnIndexOrThrow(PersonMetaData.PersonTable.AGE)));
}
c.close();
db.close();
return p;

}

public class DatabaseHelper extends SQLiteOpenHelper {

private static final String DB_NAME = "cp.db";
private static final int VERSION = 1;
private static final String CRETATE_TABLE = "CREATE TABLE person(_id INTEGER PRIMARY KEY AUTOINCREMENT,name TEXT,age INTEGER)";
private static final String DROP_TABLE = "DROP TABLE IF EXISTS person";

public DatabaseHelper(Context context) {
super(context, DB_NAME, null, VERSION);
// TODO Auto-generated constructor stub
}

@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL(CRETATE_TABLE);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL(DROP_TABLE);
db.execSQL(CRETATE_TABLE);
}

}
}

MyContentProvider

package com.example.contentprovidertest;

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;

public class MyContentProvider extends ContentProvider{

private static final String AUTHORITY = "com.example.contentprovidertest.mycontentprovider";
private static final int SINGLE_CODE = 1;//返回单个记录匹配码
private static final int MUTIPLE_CODE = 2;//返回多个记录匹配码

private static final String SINGLE_TYPE = "vnd.android.cursor.item/person";
private static final String MUTIPLE_TYPE = "vnd.android.cursor.dir/person";
//创建一个uri匹配器
private static UriMatcher uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
static{
uriMatcher.addURI(AUTHORITY, "person", MUTIPLE_CODE);
uriMatcher.addURI(AUTHORITY, "person/#", SINGLE_CODE);
}

private DatabaseAdapter.DatabaseHelper dbHelper;
@Override
public boolean onCreate() {
// TODO Auto-generated method stub
dbHelper = new DatabaseAdapter.DatabaseHelper(getContext());
return true;
}

@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
// TODO Auto-generated method stub
switch(uriMatcher.match(uri)){
case SINGLE_CODE:
SQLiteDatabase db = dbHelper.getReadableDatabase();
long id = ContentUris.parseId(uri);
selection = PersonMetaData.PersonTable._ID+"=?";
selectionArgs = new String[]{String.valueOf(id)};
return db.query(true, PersonMetaData.PersonTable.TABLE_NAME, projection, selection, selectionArgs, null, null, sortOrder,null);
case MUTIPLE_CODE:
db = dbHelper.getReadableDatabase();
return db.query(true, PersonMetaData.PersonTable.TABLE_NAME, projection, selection, selectionArgs, null, null, sortOrder,null);
}

return null;
}

@Override
public String getType(Uri uri) {
// TODO Auto-generated method stub
switch(uriMatcher.match(uri)){
case SINGLE_CODE:
return SINGLE_TYPE;
case MUTIPLE_CODE:
return MUTIPLE_TYPE;
}
return null;
}

@Override
public Uri insert(Uri uri, ContentValues values) {
// TODO Auto-generated method stub
switch(uriMatcher.match(uri)){
case MUTIPLE_CODE:
SQLiteDatabase db = dbHelper.getWritableDatabase();
long id = db.insert(PersonMetaData.PersonTable.TABLE_NAME, null, values);
uri = ContentUris.withAppendedId(uri, id);
db.close();
break;

}
return uri;
}

@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
// TODO Auto-generated method stub
switch(uriMatcher.match(uri)){
case MUTIPLE_CODE:
SQLiteDatabase db = dbHelper.getWritableDatabase();
long id = ContentUris.parseId(uri);
selection = PersonMetaData.PersonTable._ID+"=?";
selectionArgs = new String[]{String.valueOf(id)};
int row = db.delete(PersonMetaData.PersonTable.NAME, selection, selectionArgs);
db.close();
return row;
case SINGLE_CODE:
db = dbHelper.getWritableDatabase();
row = db.delete(PersonMetaData.PersonTable.NAME, selection, selectionArgs);
db.close();
return row;
}
return 0;

}

@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
// TODO Auto-generated method stub
switch(uriMatcher.match(uri)){
case MUTIPLE_CODE:
SQLiteDatabase db = dbHelper.getWritableDatabase();
long id = ContentUris.parseId(uri);
selection = PersonMetaData.PersonTable._ID+"=?";
selectionArgs = new String[]{String.valueOf(id)};
int row = db.update(PersonMetaData.PersonTable.NAME,values, selection, selectionArgs);
db.close();
return row;
case SINGLE_CODE:
db = dbHelper.getWritableDatabase();
row = db.update(PersonMetaData.PersonTable.NAME,values, selection, selectionArgs);
db.close();
return row;
}
return 0;

}

}

MainActivity

package com.example.contentprovidertest;

import android.app.Activity;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}

public void addClick(View view){
ContentResolver cr = this.getContentResolver();
//调用cp的添加方法
Uri uri = Uri.parse("content://com.example.contentprovidertest.mycontentprovider/person");
ContentValues values = new ContentValues();
values.put(PersonMetaData.PersonTable.NAME, "Jack");
values.put(PersonMetaData.PersonTable.AGE,18);
cr.insert(uri, values);
}

public void deleteClick(View view){
ContentResolver cr = this.getContentResolver();
//调用cp的添加方法
Uri uri = Uri.parse("content://com.example.contentprovidertest.mycontentprovider/person1");
cr.delete(uri, null, null);
}

public void updateClick(View view){
ContentResolver cr = this.getContentResolver();
//调用cp的添加方法
Uri uri = Uri.parse("content://com.example.contentprovidertest.mycontentprovider/person1");
ContentValues values = new ContentValues();
values.put(PersonMetaData.PersonTable.NAME, "Jack");
values.put(PersonMetaData.PersonTable.AGE,20);
cr.update(uri, values, null, null);
}

public void queryClick(View view){
ContentResolver cr = this.getContentResolver();
//调用cp的添加方法
Uri uri = Uri.parse("content://com.example.contentprovidertest.mycontentprovider/person1");
Cursor c = cr.query(uri, null, null, null, null);
while(c.moveToNext()){
System.out.println(c.getInt(c.getColumnIndexOrThrow(PersonMetaData.PersonTable._ID)));
System.out.println(c.getString(c.getColumnIndexOrThrow(PersonMetaData.PersonTable.NAME)));
System.out.println(c.getInt(c.getColumnIndexOrThrow(PersonMetaData.PersonTable.AGE)));
}
c.close();
}
}

activity_main

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.contentprovidertest.MainActivity" >

<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:text="add"
android:onClick="addClick" />

<Button
android:id="@+id/button2"
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignRight="@+id/button1"
android:layout_below="@+id/button1"
android:text="delete"
android:onClick="deleteClick" />

<Button
android:id="@+id/button3"
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/button2"
android:layout_alignRight="@+id/button2"
android:layout_below="@+id/button2"
android:text="update"
android:onClick="updateClick" />

<Button
android:id="@+id/button4"
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignRight="@+id/button3"
android:layout_below="@+id/button3"
android:text="query"
android:onClick="queryClick" />

</RelativeLayout>

AndroidMainfest

<provider android:name=".MyContentProvider"
android:authorities="com.example.contentprovidertest.mycontentprovider"/>

5.ContentProvider访问联系人



















6.Loaders概述与准备























7.使用CursorLoader加载数据





8.Loaders_自定义AsyncTaskLoader加载数据



详见：http://blog.csdn.net/dt235201314/article/details/50512749