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三 类微信界面


发布时间: 2022-11-24 22:05:00    浏览次数:30 次

一、作业内容
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。

二、作业目标
1、contentprovider主要用于在不同的应用程序之间实现数据共享的功能,它提供了一套完整的机制,允许一个程序访问另一个程序中的数据,同时还能保证被访数据的安全性。

2、在本次实验中具体表现为以下效果,在第一个APP:contentprovide中可以切换访问第二个APP:resolver,resolver可以调用contentprovider。

三、作业内容
1、首先先创建两个项目,provider和resovler

2、provider中的内容

MainActivity

 

package com.example.provider;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

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

MyDAO myDAO=new MyDAO(this);
}
}
MyContentProvider
package com.example.provider;

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;
public MyContentProvider() {

}

@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.

//getContext().getContentResolver().insert(uri, values);
return myDAO.DAOinsert(values);
}

@Override
public boolean onCreate() {
// TODO: Implement this to initialize your content provider on startup.
Context context=getContext();
myDAO=new MyDAO(context);
return false;
}

@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
package com.example.provider;

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 SQLiteDatabase database;
public MyDAO(Context context){
this.context=context;

MyDBhelper dBhelper =new MyDBhelper(context,"lxDB",null,1);
database=dBhelper.getReadableDatabase();
}

public Uri DAOinsert(ContentValues contentValues){
long rowid=database.insert("student",null,contentValues);

Uri uri=Uri.parse("content://lx.provider2/student");
Uri inserturi=ContentUris.withAppendedId(uri,rowid);
context.getContentResolver().notifyChange(inserturi,null);
return inserturi;
}
}
MyDBhelper
package com.example.provider;

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 SQLiteDatabase database;
public MyDAO(Context context){
this.context=context;

MyDBhelper dBhelper =new MyDBhelper(context,"lyr",null,1);
database=dBhelper.getReadableDatabase();
}

public Uri DAOinsert(ContentValues contentValues){
long rowid=database.insert("student",null,contentValues);

Uri uri=Uri.parse("content://lyr.provider2/student");
Uri inserturi=ContentUris.withAppendedId(uri,rowid);
context.getContentResolver().notifyChange(inserturi,null);
return inserturi;
}
}
activity_main.xml
package com.example.provider;

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 SQLiteDatabase database;
public MyDAO(Context context){
this.context=context;

MyDBhelper dBhelper =new MyDBhelper(context,"lxDB",null,1);
database=dBhelper.getReadableDatabase();
}

public Uri DAOinsert(ContentValues contentValues){
long rowid=database.insert("student",null,contentValues);

Uri uri=Uri.parse("content://lx.provider2/student");
Uri inserturi=ContentUris.withAppendedId(uri,rowid);
context.getContentResolver().notifyChange(inserturi,null);
return inserturi;
}
}
3、resovler中的内容
MainActivity
package com.example.resolver;

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 {

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

ContentResolver resolver=getContentResolver();

ContentValues values=new ContentValues();
values.put("name","lyr");
values.put("age",20);

Uri uri=Uri.parse("content://lyr.provider2/student");

Button button = findViewById(R.id.button);

button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
resolver.insert(uri,values);
}
});
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="resovler"
android:textSize="45dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.526"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.363" />

<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="insert"
android:textSize="45dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.555"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.587" />

</androidx.constraintlayout.widget.ConstraintLayout>
 
  

 

 

 
  

 
  


































































 

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