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";
@Override
protected 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() {
@Override
public 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;
@Override
protected 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() {
@Override
public 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() {
@Override
public 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() {
@Override
public 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() {
@Override
public 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);}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase){
sqLiteDatabase.execSQL("create table student(" "id integer primary key autoincrement,name varchar(20),age interger)");
}
@Override
public 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;
@Override
public 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");
}
@Override
public 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");
}
@Override
public 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);
}
@Override
public boolean onCreate() {
// TODO: Implement this to initialize your content provider on startup.
context=this.getContext();
myDAO=new MyDAO(context);
return true;
}
@Override
public 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");
}
@Override
public 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INSETR按钮
源代码地址张浪浪的仓库: ......dfafa (gitee.com)
