Android 第三次作业 contentprovider与resolver

作业 contentprovider与resolver"/>

Android 第三次作业 contentprovider与resolver

作业要求：

1、contentprovider是安卓四大组件之一，请使用其方法类进行数据获取；

2、请自建一个provider，然后在另一个app中使用resolver调用这个provider。

3、本次作业请启用新项目，理论上需要两个APP进行实验。

  首先我们新建两个新的项目，分别命名为ContentProvider和Myresolver。

我们先完成Myresolver的编写：在MainActivity.java里面写：

package com.example.myresolver;import androidx.annotation.ContentView;
import androidx.appcompat.app.AppCompatActivity;import android.content.ContentResolver;
import android.content.ContentValues;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;public class MainActivity extends AppCompatActivity {private Button button;private ContentResolver resolver;//private  static  final String AUTHORITY="hjy.Provider1";@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);button=findViewById(R.id.button);ContentResolver resolver=getContentResolver();Uri uri=Uri.parse("content://hjy.provider1/student");ContentValues values=new ContentValues();values.put("name","hjy");values.put("age",19);button.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {resolver.insert(uri,values);}});}
}

设计的resolver界面如下：

然后我们开始编写ContentProvider：

 先编写数据库有关代码，新建一个DatabaseActivity和一个MyDBhelper，代码如下：

package com.example.contentprovider;import androidx.appcompat.app.AppCompatActivity;import android.annotation.SuppressLint;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;public class DatabaseActivity2 extends AppCompatActivity {private Button button,button2,button3,button4;private MyDBhelper dBhelper;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_database2);button=findViewById(R.id.button);button2=findViewById(R.id.button2);button3=findViewById(R.id.button3);button4=findViewById(R.id.button4);MyDBhelper dBhelper=new MyDBhelper(this,"hjyDB",null,1);SQLiteDatabase database=dBhelper.getReadableDatabase();button.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {ContentValues values1=new ContentValues();values1.put("name","zhangsan");values1.put("age",19);ContentValues values2=new ContentValues();values2.put("name","lisi");values2.put("age",20);ContentValues values3=new ContentValues();values3.put("name","wangwu");values3.put("age",21);ContentValues values4=new ContentValues();values4.put("name","liuliu");values4.put("age",21);database.insert("student",null,values1);database.insert("student",null,values2);database.insert("student",null,values3);database.insert("student",null,values4);ContentValues values=new ContentValues();}});button2.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {ContentValues values=new ContentValues();values.put("age",19);database.update("student",values,"name=?",new String[]{"liuliu"});//修改liuliu的年龄为19}});button3.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {// database.execSQL("delete from student");//删除表的所有内容database.delete("student","name=?",new String[]{"liuliu"});//删除名字为liuliu的一行}});button4.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {Cursor cursor1=database.query("student",new String[]{"name"},"name=?",new String[]{"wangwu"},null,null,null);Cursor cursor2=database.rawQuery("select * from student where name=?",new String[]{"zhangsan"});//另一种查询方法Log.d("hjy",String.valueOf(cursor2.getCount()));Log.d("hjy","cursor2.getPosition:"+cursor2.getPosition());while (cursor2.moveToNext()){@SuppressLint("Range") Integer id=cursor2.getInt(cursor2.getColumnIndex("id"));@SuppressLint("Range") String name=cursor2.getString(cursor2.getColumnIndex("name"));Log.d("hjy","result"+id+name);}cursor2.close();}});}}

package com.example.contentprovider;import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;import androidx.annotation.Nullable;public class MyDBhelper extends SQLiteOpenHelper {public  MyDBhelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory,int version){super(context,"hjyDB",factory,version);}@Overridepublic void onCreate(SQLiteDatabase sqLiteDatabase){sqLiteDatabase.execSQL("create table student("+"id integer primary key autoincrement,name varchar(20),age interger)");}@Overridepublic void onUpgrade(SQLiteDatabase sqLiteDatabase,int i,int i1){}
}

DatabaseActivity的界面如下：

然后我们编写ContentProvider.java:

package com.example.contentprovider;import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;public class MyContentProvider extends ContentProvider {private  MyDAO myDAO;private Context context;@Overridepublic int delete(Uri uri, String selection, String[] selectionArgs) {// Implement this to handle requests to delete one or more rows.throw new UnsupportedOperationException("Not yet implemented");}@Overridepublic String getType(Uri uri) {// TODO: Implement this to handle requests for the MIME type of the data// at the given URI.throw new UnsupportedOperationException("Not yet implemented");}@Overridepublic Uri insert(Uri uri, ContentValues values) {// TODO: Implement this to handle requests to insert a new row.//throw new UnsupportedOperationException("Not yet implemented");return myDAO.hjyInsert(values);}@Overridepublic boolean onCreate() {// TODO: Implement this to initialize your content provider on startup.context=this.getContext();myDAO=new MyDAO(context);return true;}@Overridepublic Cursor query(Uri uri, String[] projection, String selection,String[] selectionArgs, String sortOrder) {// TODO: Implement this to handle query requests from clients.throw new UnsupportedOperationException("Not yet implemented");}@Overridepublic int update(Uri uri, ContentValues values, String selection,String[] selectionArgs) {// TODO: Implement this to handle requests to update one or more rows.throw new UnsupportedOperationException("Not yet implemented");}
}

MyDao.java:

package com.example.contentprovider;import android.content.ContentUris;
import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;public class MyDAO {private Context context;private Uri uri=Uri.parse("content://hjy.provider1");public  MyDAO(Context context){this.context=context;}// MyDBhelper dBhelper=new MyDBhelper(context,"hjyDB",null,1);// SQLiteDatabase database=dBhelper.getWritableDatabase();public Uri hjyInsert(ContentValues values){MyDBhelper dBhelper=new MyDBhelper(context,"hjyDB",null,1);SQLiteDatabase database=dBhelper.getWritableDatabase();ContentValues values1=new ContentValues();values1.put("name","zhangsan");values1.put("age",19);Uri uri=Uri.parse("content://hjy.provider1/student");long rowId= database.insert("student",null,values1);Uri  inserturi= ContentUris.withAppendedId(uri,rowId);return inserturi;}
}

当然我们还要修改Mainfest里的内容，首先要增加permission

修改provider里的内容

 以上就是代码编写的内容，然后我们运行contentprovider和resolver

运行结果：

 点击resolver里的button前：

点击后：

仓库：胡宝宝/hubaobaoh