Android Studio Three

文章目录

• 一，设计目标
• 二，功能说明
• 三，代码解析
• 四，运行展示截图
• 五，源码仓库地址

一、设计目标

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、功能说明

在Resolver中点击insert，向Provider中插入数据，在第二个APP：Resolver中调用第一个APP：Provider。

三、 代码解析

Provider

MainActivity.java

在其中只需要创建一个MyDAO的对象

package com.example.provider;

import androidx.appcompat.app.AppCompatActivity;

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);
    }
}

MyDAO.java

在这个java文件中，首先利用MyDBHelper的构造函数构建了一个名为”cqDB”的数据库，版本为1

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,"cqDB",null,1);
        database=dBhelper.getWritableDatabase();
    }

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

        Uri uri=Uri.parse("content://cq.provider2");
        Uri inserturi=ContentUris.withAppendedId(uri,rowid);
        context.getContentResolver().notifyChange(inserturi,null);
        return inserturi;
    }

}

MyDBhelper.java

这个文件是用来创建数据库和生成数据库，当第一次建立数据库时会进行打印。

package com.example.provider;

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

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, name, factory, version);
        Log.d("cq","MyDBhelper is running.");
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        sqLiteDatabase.execSQL( " create table student ( " +
                "id integer primary key autoincrement,name varchar,age integer)");
        Log.d("cq","onCreate is running.");

    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }
}

MyContentProvider.java

调用MyBAO的构造器

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 myDb;
    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.

        return myDb.DAOinsert(values);
    }

    @Override
    public boolean onCreate() {
        // TODO: Implement this to initialize your content provider on startup.

        Context context=getContext();
        myDb=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");
    }
}

Resolver

MainActivity.java

使用了put函数将需要的值填入values中，使用绑定按钮的点击事件为resolver调用insert插入函数

vpackage 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();

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

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

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

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                resolver.insert(uri,values);

            }
        });
    }
}

activity_main.xml

进行界面设计添加一个TextView和一个Button

四、运行展示截图

Resolver运行界面

插入了数据

五、源码仓库地址

Provider

https://gitee.com/Chen__address/Provider

Resolver

https://gitee.com/Chen__address/Resolver

Original: https://blog.csdn.net/m0_67586252/article/details/128023991
Author: 陈强ya
Title: Android Studio Three