内容提供器（二 - 跨程序数据共享）

知识点：

ContentResolver中的增删改查方法都是不接受表名参数的，而是用Uri代替，这个参数被称为内容Uri.（由权限+路径组成）

最标准的格式：

content：//com.example.app.provider/table1

content：//com.example.app.provider/table1/1

使用Uri.parse（）方法，可以将上述字符串解析成Uri对象、

使用通配符分别匹配这两种格式的内容URI

规则：*：表示匹配任意长度的任意字符（查表）

#：表示匹配任意长度的数字（查行）

创建内容提供器的步骤

共重写6个方法：

1 onCreate（） 2 query（） 3 insert（） 4 update（） 5 delete（）

6 getType（）（根据传入的内容返回相应的MIME类型）

借助UriMatcher这个类可以实现匹配Uri的功能，根据传入的自定义代码，在传出，就可以匹配相应的增删改查CURD的操作。

实现 ：修改之前的DataBasetest 作为数据共享的对象

主活动的布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Create database"
android:id="@+id/create_database"/>

<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Add data"
android:id="@+id/add_data"/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="update_data"
android:id="@+id/update_data"/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Delete_data"
android:id="@+id/Delete_data"/>

<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Select_data"
android:id="@+id/Select_data"/>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/replace_data"
android:text="Replace data"/>
</LinearLayout>

主活动

package com.example.databasetest;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

private  MyDatabaseHelper dbHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
dbHelper = new MyDatabaseHelper(this , "BookStore.db" ,null ,2);
Button addData = (Button) findViewById(R.id.add_data);
addData.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SQLiteDatabase db = dbHelper.getReadableDatabase();
ContentValues values = new ContentValues();//用于组装数据
values.put("name","The Da Vinci Code");
values.put("author","Dan Brown");
values.put("pages","454");
values.put("price","16.53");
db.insert("Book" , null , values);//第二个参数用于未指定添加数据的情况下为可为空的列赋值为null
values.clear();
values.put("name","The Da Vinci Code1");
values.put("author","Dan Brown1");
values.put("pages","411");
values.put("price","16.53");
db.insert("Book" , null , values);

}
});
Button updateData = (Button) findViewById(R.id.update_data);
updateData.setOnClickListener(new View.OnClickListener() {
@Override

4000
public void onClick(View v) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("price" , 10.99);
db.update("Book" ,values , "name = ?" ,new String[]{"The Da Vinci Code"});
}
});

Button deleteButton = (Button) findViewById(R.id.Delete_data);
deleteButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
db.delete("Book","pages > ?", new String[]{"450"});
}
});

Button selectDatabase = (Button) findViewById(R.id.Select_data);
selectDatabase.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
Cursor cursor = db.query("Book" , null ,null, null,null,null,null);
//
//                Uri uri = Uri.parse("content://com.example.databasetest.provider/book"); 与上方的方法相同
//                Cursor cursor = getContentResolver().query(uri, null, null,
//                        null, null);
System.out.println(cursor);
if (cursor.moveToFirst()){
do{
String name = cursor.getString(cursor.getColumnIndex("name"));
String author = cursor.getString(cursor.getColumnIndex("author"));
int pages = cursor.getInt(cursor.getColumnIndex("pages"));
double price = cursor.getDouble(cursor.getColumnIndex("price"));
Log.d("MainActicity" , name);
Log.d("MainActicity" , author);
Log.d("MainActicity" ,""+ pages);
Log.d("MainActicity" ,""+ price);

}while (cursor.moveToNext());
}
cursor.close();
}
});

Button replaceData = (Button) findViewById(R.id.replace_data);
replaceData.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
db.beginTransaction();//开启事务
try{
db.delete("Book",null,null);
//                    if(true){//手动抛出一个异常
//                        throw new NullPointerException();
//                    }
ContentValues values =new ContentValues();
values.put("name","The Da Vinci Code22");
values.put("author","Dan Brown221");
values.put("pages","411");
values.put("price","16.53");
db.insert("Book" , null , values);
db.setTransactionSuccessful();//事务成功执行
}catch (Exception e){
e.printStackTrace();
}finally {
db.endTransaction();//结束事务
}
}
});
Button createDatabase = (Button)findViewById(R.id.create_database);
createDatabase.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
dbHelper.getWritableDatabase();
}
});
}
}

AndroidManifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.databasetest">

<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

<provider
android:name="com.example.databasetest.DatabaseProvider"

android:authorities="com.example.databasetest.provider"

android:exported="true">

</provider>
</application>

</manifest>

对数据操作重写的类

package com.example.databasetest;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import android.widget.Toast;

public class MyDatabaseHelper extends SQLiteOpenHelper {
public static final String CREATE_BOOK ="create table Book("
+" id integer primary key autoincrement , author text , "
+"price real, pages integer , name text"
+ " ,category_id integer )";//在版本2的基础上增加外键;
public static  final String CREATE_CATEGORY = "create table Category ("
+"id integer primary key autoincrement,"
+"category_name text ,"
+"category_code integer)";

private Context mContext;

public   MyDatabaseHelper(Context context , String name , SQLiteDatabase.CursorFactory factory , int verson){//CursorFactory为查询数据时返回自定义的Cursor
super(context , name , factory , verson);
mContext = context ;
}

@Override
public void onCreate(SQLiteDatabase db) {
// Toast.makeText(mContext,"Create succeed" ,Toast.LENGTH_SHORT).show();
db.execSQL(CREATE_BOOK);
db.execSQL(CREATE_CATEGORY);
// Log.d("MyDatabaseHelper", CREATE_BOOK);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {//对数据库进行升级  执行的条件是在创建时的版本号大于上一次的版本号
Log.d("MyDatabaseHelper","zhangyu"+ oldVersion);
switch (oldVersion){

case 1:db.execSQL(CREATE_CATEGORY);
case 2:db.execSQL("alter table Book add column category_id integer");
//Log.d("MyDatabaseHelper","zhangyu"+ oldVersion);
default:
}
}
}

内容提供

package com.example.databasetest;

import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.support.annotation.Nullable;

/**
* Created by yuwei on 2016/9/21.
*/
public class DatabaseProvider extends ContentProvider {
public static final int BOOK_DIR = 0;

public static final int BOOK_ITEM = 1;

public static final int CATEGORY_DIR = 2;

public static final int CATEGORY_ITEM = 3;

public static final String AUTHORITY = "com.example.databasetest.provider";
private static UriMatcher uriMatcher;
private  MyDatabaseHelper databaseHelper;
static {
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
uriMatcher.addURI(AUTHORITY,"book",BOOK_DIR);
uriMatcher.addURI(AUTHORITY,"book/#",BOOK_ITEM);
uriMatcher.addURI(AUTHORITY,"category",CATEGORY_DIR);
uriMatcher.addURI(AUTHORITY,"category/#",CATEGORY_ITEM);
}

@Override
public boolean onCreate() {
databaseHelper = new MyDatabaseHelper(getContext() , "BookStore.db" ,null,2);
return true;
}

@Nullable
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
SQLiteDatabase db = da
10bef
tabaseHelper.getReadableDatabase();
Cursor cursor = null ;
switch (uriMatcher.match(uri)){
case BOOK_DIR:
cursor = db.query("Book",projection,selection,selectionArgs,null,null,sortOrder);
break;
case BOOK_ITEM:
String bookId = uri.getPathSegments().get(1);//将UIR权限之后的部分以/分开，并将结果放入一个字符串列表中，第0个位置是路径。1个位置是id
cursor =  db.query("Book",projection,"id= ?",new String[]{bookId},null,null,sortOrder);
break;
case CATEGORY_DIR:
cursor = db.query("Category",projection,selection,selectionArgs,null,null,sortOrder);
break;
case CATEGORY_ITEM:
String categoryId = uri.getPathSegments().get(1);
cursor = db.query("Category",projection,"id= ?",new String[]{categoryId},null,null,sortOrder);
default:
break;
}
return cursor;

}

@Nullable
@Override
public Uri insert(Uri uri, ContentValues values) {
//   System.out.println(uri);
//  System.out.println(values );
SQLiteDatabase db = databaseHelper.getWritableDatabase();
Uri uriReturn = null;
// System.out.println(uriMatcher.match(uri));
switch (uriMatcher.match(uri)) {
case BOOK_DIR:
case BOOK_ITEM:
long newBookId = db.insert("Book", null, values);
uriReturn = Uri.parse("content://" + AUTHORITY + "/book/" + newBookId);
//       System.out.println("张玉玮");
break;
case CATEGORY_DIR:
case CATEGORY_ITEM:
long newCategoryId = db.insert("Category", null, values);
uriReturn = Uri.parse("content://" + AUTHORITY + "/category/" + newCategoryId);
break;
default:
break;
}
return uriReturn;
}

@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
System.out.println(uri);
SQLiteDatabase db = databaseHelper.getWritableDatabase();
int updatedRows = 0;
switch (uriMatcher.match(uri)){
case BOOK_DIR:
updatedRows = db.update("Book" , values , selection ,selectionArgs);
break;
case BOOK_ITEM:
System.out.println(uri);
String bookId = uri.getPathSegments().get(1);
updatedRows = db.update("Book",values,"id=?",new String[]{bookId});
break;
case CATEGORY_DIR:
updatedRows = db.update("Category" , values , selection ,selectionArgs);
break;
case CATEGORY_ITEM:
String categoryId = uri.getPathSegments().get(1);
updatedRows = db.update("Category" , values , "id=?" ,new String[]{categoryId});
default:
break;
}
return updatedRows;
}

@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
SQLiteDatabase db = databaseHelper.getWritableDatabase();
int deletedRows = 0;
switch (uriMatcher.match(uri)){
case BOOK_DIR:
deletedRows = db.delete("Book" , selection ,selectionArgs);
break;
case BOOK_ITEM:
String bookId = uri.getPathSegments().get(1);
deletedRows = db.delete("Book" , "id=?" ,new String[]{bookId});
break;
case CATEGORY_DIR:
deletedRows = db.delete("Category" , selection ,selectionArgs);
break;
case CATEGORY_ITEM:
String categoeyId = uri.getPathSegments().get(1);
deletedRows = db.delete("Category" , "id=?" ,new String[]{categoeyId});
break;
default:
break;
}
return deletedRows;
}

@Nullable
@Override
public String getType(Uri uri) {
System.out.println("我是getType");
switch (uriMatcher.match(uri)) {
case BOOK_DIR:
return "vnd.android.cursor.dir/vnd.com.example.databasetest.provider.book";
case BOOK_ITEM:
return "vnd.android.cursor.item/vnd.com.example.databasetest.provider.book";
case CATEGORY_DIR:
return "vnd.android.cursor.dir/vnd.com.example.databasetest.provider.category";
case CATEGORY_ITEM:
return "vnd.android.cursor.item/vnd.com.example.databasetest.provider.category";
}
return null;
}
}

用于查出或修改DataBaseTest共享的数据的app

package com.example.providertest;

import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {
private String newId;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button addData = (Button) findViewById(R.id.add_data);
addData.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Uri uri = Uri.parse("content://com.example.databasetest.provider/book");
ContentValues values = new ContentValues();
values.put("name","zhangyuwei");
values.put("author","zhnagyuw");
values.put("pages",400);
values.put("price",22.85);
System.out.println(uri);
Uri newUri = getContentResolver().insert(uri , values);
if(newUri == null){
System.out.println((1234));
}
newId = newUri.getPathSegments().get(1);//用于后来的更新和删除的id 使用这样的方法只能获得一条id 也就是说只能删除最近一条插入的id
}
});

Button  queryData = (Button) findViewById(R.id.query_data);
queryData.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Uri uri = Uri.parse("content://com.example.databasetest.provider/book");
Cursor cursor = getContentResolver().query(uri, null, null, null, null);
if(cursor!=null){
while(cursor.moveToNext()){
String name = cursor.getString(cursor.getColumnIndex("name"));
String author = cursor.getString(cursor.getColumnIndex("author"));
int pages = cursor.getInt(cursor.getColumnIndex("pages"));
double price = cursor.getDouble(cursor.getColumnIndex("price"));
Log.d("MainActivity","book name is "+name);
Log.d("MainActivity","book author is "+author);
Log.d("MainActivity","book pages is "+pages);
Log.d("MainActivity","book price is "+price);

}
}
cursor.close();

}
});

Button updataData =(Button) findViewById(R.id.updata_data);
updataData.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Uri uri = Uri.parse("content://com.example.databasetest.provider/book/"+newId);
System.out.println(newId+"");
ContentValues values = new ContentValues();
values.put("name","zhangyuwe1121312i");
values.put("author","zhnagy123123uw");
values.put("pages",4010);
values.put("price",22.815);
getContentResolver().update(uri , values , null ,null);
}
});

Button button = (Button)findViewById(R.id.delete_data);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Uri uri = Uri.parse("content://com.example.databasetest.provider/book/"+newId);
getContentResolver().delete(uri,null,null);
}
});

}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="addData"
android:id="@+id/add_data"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="queryData"
android:id="@+id/query_data"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/updata_data"
android:text="updata_data"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="delete_data"
android:id="@+id/delete_data"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />

</LinearLayout>

注意Uri的匹配问题，很容易 出错