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ContentProvider内容提供者的使用_在contentprovider中使用者

作者：我家小花儿 | 2024-03-16 00:55:49

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在contentprovider中使用者

  1. ContentProvider内容提供者

            ContentProvider是安卓四大组件之一，用来共享程序内的数据。当你需要把你的应用程序数据共享给其它的应用程序时，才需要用它，该组件对外提供了其他应用可以直接访问的增删查改的方法。并且 ContentProvider暴露了自己的数据，不管应用程序是否启动，都能访问到。

      以下是我自己运用ContentProvider写的一个测试其中涉及到了：ContentProvider内容提供者 ； ContentResolver内容访问者。ContentProvider主要是提供数据资源，ContentResolver可以访问到ContentProvider的资源，并可以对其增删查改。两个运用程序可以直接访问

第一步写一个提供数据的应用程序，这个程序中也可以开始提供添加数据
  activity_main.xml 


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.g150825_16class.MainActivity">

    <EditText
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:hint="Id:"
    android:id="@+id/et_main_id"
    />
    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="Name:"
        android:id="@+id/et_main_name"
        />
    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="Age:"
        android:id="@+id/et_main_age"
        />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        >
   <Button
       android:layout_width="0dp"
       android:layout_height="wrap_content"
       android:text="保存"
       android:layout_weight="1"
       android:onClick="save"
       />
        <Button
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:text="查询"
            android:layout_weight="1"
            android:onClick="query"
            />

    </LinearLayout>

    <ListView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@android:id/list"
    >

</ListView>


</LinearLayout>


2. 
MainActivity.java
package com.example.g150825_16class;

import android.app.ListActivity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AlertDialog;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;

import com.example.g150825_16class.com.zking.db.DbHelper;

public class MainActivity extends ListActivity {
    private EditText et_main_id;
    private EditText et_main_name;
    private EditText et_main_age;
    private SQLiteDatabase db;

    private SimpleCursorAdapter simpleCursorAdapter;
    private Cursor cursor;
    private ListView listview;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //实例化DbHelper
        DbHelper dbHelper=new DbHelper(this,"person.db",null,2);
        //获取SQLiteDataBase对象（类似Hibernate中Session）
        db = dbHelper.getReadableDatabase();
        //获取ListView
        listview = getListView();
        initViews();
        //查询所有
        cursor = db.query(false,"person",null,null,null,null,null,null,null);
        //循环游标
        //把值放入list
        //设置适配器
        //SimpleCursorAdapter
      simpleCursorAdapter = new SimpleCursorAdapter(this, R.layout.itm_list_view,                cursor,new String[]{"_id","name","age"},new int[]{R.id.tv_item_list_id,R.id.tv_item_list_name,R.id.tv_item_list_age});
        listview.setAdapter(simpleCursorAdapter);

        initEvents();//初始化事件


    }

    private void initEvents() {

        //给ListView添加长按事件
        listview.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
                //获取点击的每一行的值
                LinearLayout root= (LinearLayout) view;
                String id=((TextView)root.findViewById(R.id.tv_item_list_id)).getText().toString();
                String name=((TextView)root.findViewById(R.id.tv_item_list_name)).getText().toString();
                String age=((TextView)root.findViewById(R.id.tv_item_list_age)).getText().toString();
                //弹出对话框（自定义）
                final AlertDialog.Builder builder=new AlertDialog.Builder(MainActivity.this);

                final AlertDialog dialog=builder.create();

                //设置点击空白，不取消对话框
                dialog.setCancelable(false);
                //解析布局文件
                View v=getLayoutInflater().inflate(R.layout.dialog_listview,null);
                ((TextView)v.findViewById(R.id.tv_dialog_listview_id)).setText("修改："+id);
                ((EditText)v.findViewById(R.id.et_dialog_listview_name)).setText(name);
                ((EditText)v.findViewById(R.id.et_dialog_listview_age)).setText(age);

                ((Button)v.findViewById(R.id.btn_dialog_listview_sure)).setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        Toast.makeText(MainActivity.this, "执行修改操作", Toast.LENGTH_SHORT).show();
                        dialog.dismiss();//关闭当前的对话框
                    }
                });
                ((Button)v.findViewById(R.id.btn_dialog_listview_cancel)).setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        dialog.dismiss();//关闭当前的对话框
                    }
                });
                dialog.setView(v);
                dialog.show();
                return true;
            }
        });
    }

    private void initViews() {
        et_main_id = (EditText) findViewById(R.id.et_main_id);
        et_main_name = (EditText) findViewById(R.id.et_main_name);
        et_main_age = (EditText) findViewById(R.id.et_main_age);
    }

    public void save(View view){
        String name=et_main_name.getText().toString();
        int age=Integer.parseInt(et_main_age.getText().toString());

        //保存到数据库中
        ContentValues values=new ContentValues();//Map
        values.put("name",name);
        values.put("age",age);
        values.putNull("_id");
        db.insert("person","name",values);
        Toast.makeText(MainActivity.this, "添加成功", Toast.LENGTH_SHORT).show();

        cursor=queryAllPerson(null);
        //通知适配器发生改变
        simpleCursorAdapter.changeCursor(cursor);
    }

    public Cursor queryAllPerson(String name){
        //Cursor cursor=db.query(false,"person",null,null,null,null,null,null,null);
        Cursor cursor;
        if(!"".equals(name)){
            Log.i("test","name="+name);
            cursor=db.rawQuery("select * from person where name like ? limit ?,?",new String[]{"%"+name+"%",2+"",2+""});
        }else{
            Log.i("test","查询所有");
            cursor = db.rawQuery("select * from person",null);
        }
        return cursor;
    }

    public void query(View view){
//        if(!TextUtils.isEmpty(et_main_name.getText())){
        String name=et_main_name.getText().toString();
        cursor=queryAllPerson(name);
        //通知适配器发生改变
        simpleCursorAdapter.changeCursor(cursor);
    }

}

3.
MyPersonProvider.Java

public class MyPersonProvider extends ContentProvider{

    private DbHelper dbHelper;
    private SQLiteDatabase sqLiteDatabase;

    @Override
    public boolean onCreate() {
        Log.i("test","onCreate");
        //初始化DB
        dbHelper = new DbHelper(getContext(),"person.db",null,2);
        sqLiteDatabase = dbHelper.getReadableDatabase();
        return false;
    }


    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
        Log.i("test","query");

        //查询数据库中的所有数据
        return sqLiteDatabase.query(false,"person",projection,selection,selectionArgs,null,null,sortOrder,null);

    }


    @Nullable
    @Override
    public String getType(Uri uri) {
        Log.i("test","getType");
        return null;
    }


    @Nullable
    @Override
    public Uri insert(Uri uri, ContentValues values) {
        Log.i("test","insert");
        sqLiteDatabase.insert("person",null,values);
        return null;
    }

    @Nullable
    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        Log.i("test","delete");
        sqLiteDatabase.delete("person",selection,selectionArgs);
        return 0;
    }

    @Nullable
    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        Log.i("test","update");
        sqLiteDatabase.update("person",values,selection,selectionArgs);
        return 0;
    }
}



在清单文件中
<!--配置内容提供者-->
<provider
    android:authorities="com.example.g150825_16class.PERSONS"
    android:name=".com.zking.provider.MyPersonProvider"
    android:exported="true"
    ></provider>


以上是contentProvider提供数据资源
 
 
 
 
那么ContentResolver内容访问者可以对上一个应用程序进行直接的访问
 
 


 
 
activity_main.xml
 
 
 
 
 
 
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main"
    android:layout_width="match_parent" android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.g150825_24contentresole.MainActivity">

  <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:onClick="getData"
      android:text="获取数据"
      />
  <EditText
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:hint="Id:"
      android:id="@+id/et_main_id"
      />
  <EditText
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:hint="Name:"
      android:id="@+id/et_main_name"
      />
  <EditText
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:hint="Age:"
      android:id="@+id/et_main_age"
      />

  <LinearLayout
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:orientation="horizontal"
      >
    <Button
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="保存"
        android:layout_weight="1"
        android:onClick="save"
        />
</LinearLayout>
<!--修改-->
  <EditText
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:hint="修改Id:"
      android:id="@+id/et_main_id_update"
      />
  <EditText
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:hint="修改Name:"
      android:id="@+id/et_main_name_update"
      />
  <EditText
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:hint="修改Age:"
      android:id="@+id/et_main_age_update"
      />

  <LinearLayout
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:orientation="horizontal"
      >
    <Button
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="修改保存"
        android:layout_weight="1"
        android:onClick="update"
        />
  </LinearLayout>

  <!--删除-->
  <EditText
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:hint="根据name删除:"
      android:id="@+id/et_main_id_delete"
      />


  <LinearLayout
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:orientation="horizontal"
      >
    <Button
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="删除保存"
        android:layout_weight="1"
        android:onClick="delete"
        />
  </LinearLayout>



</LinearLayout>

 
 
 
 
MainActivity.java  这个文件中的URL是十分重要的，它是让两个程序进行访问的重要桥梁


package com.example.g150825_24contentresole;
import android.content.ContentProvider;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;


public class MainActivity extends AppCompatActivity {
    private ContentResolver cr;
    private ListView listview;
    private Cursor cursor;
    private EditText et_main_id;
    private EditText et_main_name;
    private EditText et_main_age;
    private Uri uri;
    private EditText et_main_id_update;
    private EditText et_main_name_update;
    private EditText et_main_age_update;
    private EditText et_main_id_delete;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //获取内容访问者
        initViews();
        cr = getContentResolver();
    }
    private void initViews() {
        et_main_id = (EditText) findViewById(R.id.et_main_id);
        et_main_name = (EditText) findViewById(R.id.et_main_name);
        et_main_age = (EditText) findViewById(R.id.et_main_age);
       //修改
        et_main_id_update = (EditText) findViewById(R.id.et_main_id_update);
        et_main_name_update = (EditText) findViewById(R.id.et_main_name_update);
        et_main_age_update = (EditText) findViewById(R.id.et_main_age_update);
        //删除
        et_main_id_delete = (EditText) findViewById(R.id.et_main_id_delete);

    }
    //查
    public void getData(View view){
        //访问数据
        uri = Uri.parse("content://com.example.g150825_16class.PERSONS");
        cursor = cr.query(uri,null,null,null,null);
//拿取数据
        while (cursor.moveToNext()){
            int pid= cursor.getInt(cursor.getColumnIndex("_id"));
            String name= cursor.getString(cursor.getColumnIndex("name
            int age= cursor.getInt(cursor.getColumnIndex("age"));
            Log.i("test",pid+"aa"+name+"bb"+age+"cc");


        }
    }

    //增加
    public void save(View view){
        String name=et_main_name.getText().toString();
        int age=Integer.parseInt(et_main_age.getText().toString());
        uri = Uri.parse("content://com.example.g150825_16class.PERSONS");
        //保存到数据库中
        ContentValues values=new ContentValues();//Map
        values.put("name",name);
        values.put("age",age);
        values.putNull("_id");
        cr.insert(uri,values);
        Toast.makeText(MainActivity.this, "添加成功", Toast.LENGTH_SHORT).show();
    }

    //修改
    public  void update(View view){
        Log.i("test","dddd");
        String name=et_main_name_update.getText().toString();
        int age=Integer.parseInt(et_main_age_update.getText().toString());
        int pid=Integer.parseInt(et_main_age_update.getText().toString());
        //url
        uri = Uri.parse("content://com.example.g150825_16class.PERSONS");
        ContentValues values=new ContentValues();//Map
        values.put("name",name);
        values.put("age",age);
        String aa="_id=?";
        String[] bb=new String[]{String.valueOf(pid)};
        cr.update(uri,values,aa,bb);
        Toast.makeText(MainActivity.this, "修改成功", Toast.LENGTH_SHORT).show();
    }

    //删除
    public void delete(View view){
        String name=et_main_id_delete.getText().toString();
        uri = Uri.parse("content://com.example.g150825_16class.PERSONS");
        cr.delete(uri,"name=?",new String[]{name});
        Toast.makeText(MainActivity.this, "删除成功", Toast.LENGTH_SHORT).show();

    }


1、ContentProvider内容提供者的应用程序


}




2、ContentResolver内容访问者





 


                

        
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