实例2

ContentProviderDemo.zip
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在自己的用户目录里边创建的数据库，自己提供provider，自己访问自己的数据库

效果

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AndroidManifest.xml

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MyContentProvider.java

  1. package com.example.contentproviderdemo;
  3. import android.content.ContentProvider;
  4. import android.content.ContentUris;
  5. import android.content.ContentValues;
  6. import android.content.Context;
  7. import android.content.IntentFilter;
  8. import android.content.UriMatcher;
  9. import android.database.Cursor;
  10. import android.database.sqlite.SQLiteDatabase;
  11. import android.database.sqlite.SQLiteOpenHelper;
  12. import android.net.Uri;
  13. import android.util.Log;
  15. public class MyContentProvider extends ContentProvider {
  16.     private DBHelper mDBHelper;
  17.     private SQLiteDatabase mDB;
  18.     public MyContentProvider() {
  20.     }
  22.     //定义为静态的，可以在静态域里边初始化
  23.     public static UriMatcher sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
  24.     private static final String authority = "MyContentProvider";
  26.     private static final int PERSONS = 0x111;
  28.     private static final int PERSONS_ID = 0x222;
  30.     //静态域初始化
  31.     static {
  32.         //content://MyContentProvider/person
  33.         sUriMatcher.addURI(authority,"person",PERSONS);
  34.         //content://MyContentProvider/person/id
  35.         sUriMatcher.addURI(authority,"person/#",PERSONS_ID);
  36.     }
  37.     @Override
  38.     public int delete(Uri uri, String selection, String[] selectionArgs) {
  39.         // Implement this to handle requests to delete one or more rows.
  40.         throw new UnsupportedOperationException("Not yet implemented");
  41.     }
  43.     @Override
  44.     public String getType(Uri uri) {
  45.         // TODO: Implement this to handle requests for the MIME type of the data
  46.         // at the given URI.
  47.         //vnd.android.cursor.item/ 单记录
  48.         //vnd.android.cursor.dir/  多记录
  49.         String type = null;
  50.         int code = sUriMatcher.match(uri);
  51.         switch (code) {
  52.             case PERSONS_ID:
  53.                 type = "vnd.android.cursor.item/person";
  54.                 break;
  55.             case PERSONS:
  56.                 type = "vnd.android.cursor.dir/person";
  57.                 break;
  58.             default:
  59.                 break;
  60.         }
  61.         return type;
  62.     }
  64.     @Override
  65.     public Uri insert(Uri uri, ContentValues values) {
  66.         // TODO: Implement this to handle requests to insert a new row.
  67.         mDB = mDBHelper.getReadableDatabase();
  68.         long id = mDB.insert("person",null,values);
  69.         //返回组合好的uri 类似：//content://MyContentProvider/person/id
  70.         return ContentUris.withAppendedId(uri,id);
  72.     }
  74.     @Override
  75.     public boolean onCreate() {
  76.         // TODO: Implement this to initialize your content provider on startup.
  78.         mDBHelper = new DBHelper(getContext());
  79.         return true  ;
  80.     }
  82.     @Override
  83.     public Cursor query(Uri uri, String[] projection, String selection,
  84.                         String[] selectionArgs, String sortOrder) {
  85.         // TODO: Implement this to handle query requests from clients.
  86.         Log.d("15pb","MyContentProvider::query");
  87.         mDB = mDBHelper.getReadableDatabase();
  88.         int code = sUriMatcher.match(uri);
  89.         if (code==PERSONS){
  90.             return mDB.query("person",new String[]{"_id","name"},null,null,null,null,null);
  92.         }else if(code==PERSONS_ID){
  93.             long id = ContentUris.parseId(uri);
  94.             return mDB.query("person",new String[]{"_id","name"},"_id=?",new String[]{""+id},null,null,null);
  96.         }
  97.         return null;
  98.     }
  100.     @Override
  101.     public int update(Uri uri, ContentValues values, String selection,
  102.                       String[] selectionArgs) {
  103.         // TODO: Implement this to handle requests to update one or more rows.
  104.         throw new UnsupportedOperationException("Not yet implemented");
  105.     }
  106. }

DBHelper.java

  1. package com.example.contentproviderdemo;
  3. import android.content.Context;
  4. import android.database.sqlite.SQLiteDatabase;
  5. import android.database.sqlite.SQLiteOpenHelper;
  7. import androidx.annotation.Nullable;
  9. public class DBHelper extends SQLiteOpenHelper {
  10.     public DBHelper(@Nullable Context context) {
  11.         super(context, "mydata.db", null, 1);
  12.     }
  14.     public DBHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
  15.         super(context, name, factory, version);
  16.     }
  18.     @Override
  19.     public void onCreate(SQLiteDatabase db) {
  20.         //创建表
  21.         db.execSQL("create table person(_id integer primary key autoincrement,name varchar(20))");
  22.    }
  24.     @Override
  25.     public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
  27.     }
  28. }

MainActivity.java

  1. package com.example.contentproviderdemo;
  3. import android.content.ContentResolver;
  4. import android.content.ContentValues;
  5. import android.database.Cursor;
  6. import android.net.Uri;
  7. import android.os.Bundle;
  8. import android.util.Log;
  9. import android.view.View;
  11. import androidx.appcompat.app.AppCompatActivity;
  13. public class MainActivity extends AppCompatActivity {
  15.     @Override
  16.     protected void onCreate(Bundle savedInstanceState) {
  17.         super.onCreate(savedInstanceState);
  18.         setContentView(R.layout.activity_main);
  19.     }
  21.     public void btnClick(View view) {
  22.         // 1. 获取内容解析者
  23.         ContentResolver resolver = getContentResolver();
  24.         // 2. 创建URI
  25.         Uri uri = Uri.parse("content://"+"MyContentProvider");
  26.         // 3. 查询
  27.         Cursor cursor = resolver.query(uri,null,null,null,null,null);
  28.         Log.d("15pb","cursor:"+cursor);
  29.     }
  31.     public void btnClick1(View view) {
  32.         // 1. 获取内容解析者
  33.         ContentResolver resolver = getContentResolver();
  34.         // 2. 创建URI
  35.         Uri uri = Uri.parse("content://"+"MyContentProvider");
  36.         // 3. 创建数据
  37.         for (int i = 0; i < 100; i++) {
  38.             ContentValues values = new ContentValues();
  39.             values.put("_id",""+i);
  40.             values.put("name","王大锤"+i);
  41.             resolver.insert(uri,values);
  42.         }
  43.         //4.查询数据
  44.         Uri uri1 = Uri.parse("content://"+"MyContentProvider"+"/person");
  45.         Cursor cursor = resolver.query(uri1,null,null,null,null,null);
  46.         Log.d("15pb","cursor:"+cursor);
  47.         while (cursor.moveToNext()){
  48.             int id = cursor.getInt(0);
  49.             String name = cursor.getString(1);
  50.             Log.d("15pb","id:"+id+"name="+name);
  51.         }
  53.     }
  55.     public void btnClick2(View view) {
  56.         // 1. 获取内容解析者
  57.         ContentResolver resolver = getContentResolver();
  58.         // 2. 创建URI
  59.         Uri uri = Uri.parse("content://"+"MyContentProvider");
  60.         // 3. 创建数据
  61.         for (int i = 0; i < 100; i++) {
  62.             ContentValues values = new ContentValues();
  63.             values.put("_id",""+i);
  64.             values.put("name","王大锤"+i);
  65.             resolver.insert(uri,values);
  66.         }
  67.         //4.查询数据
  68.         Uri uri1 = Uri.parse("content://"+"MyContentProvider"+"/person/10");
  69.         Cursor cursor = resolver.query(uri1,null,null,null,null,null);
  70.         Log.d("15pb","cursor:"+cursor);
  71.         while (cursor.moveToNext()){
  72.             int id = cursor.getInt(0);
  73.             String name = cursor.getString(1);
  74.             Log.d("15pb","id:"+id+"name="+name);
  75.         }
  77.     }
  78. }

activity_main.xml

  1. <?xml version="1.0" encoding="utf-8"?>
  2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  3.     xmlns:app="http://schemas.android.com/apk/res-auto"
  4.     xmlns:tools="http://schemas.android.com/tools"
  5.     android:orientation="vertical"
  6.     android:layout_width="match_parent"
  7.     android:layout_height="match_parent"
  8.     tools:context=".MainActivity">
  10.     <Button
  11.         android:id="@+id/btn1"
  12.         android:onClick="btnClick"
  13.         android:text="访问内容提供者"
  14.         android:layout_width="match_parent"
  15.         android:layout_height="wrap_content"></Button>
  17.     <Button
  18.         android:id="@+id/btn2"
  19.         android:onClick="btnClick1"
  20.         android:text="访问内容提供者-插入数据"
  21.         android:layout_width="match_parent"
  22.         android:layout_height="wrap_content"></Button>
  23.     <Button
  24.         android:id="@+id/btn3"
  25.         android:onClick="btnClick2"
  26.         android:text="访问内容提供者-查询指定数据"
  27.         android:layout_width="match_parent"
  28.         android:layout_height="wrap_content"></Button>
  30. </LinearLayout>

ContentProvider案例分析

ContentProvider案例.pdf