用自定义ContentProvider实现对数据库的增、删、改、查操作

本次对于数据库的操作是在不同的APP中进行的。下面的前四篇是在一个APP中，后面的是在另一个APP中

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首先自定义一个SqliteOpenHelper.完成对数据库的创建和数据库内table的创建

package com.example.content_provider_03;

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

public class My_Db_Helper  extends  SQLiteOpenHelper
{

    public My_Db_Helper(Context context)
            
    {
        super(context, "hello.db", null, 1);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase arg0)
    {
      String sql="create table if not exists reg(_id integer primary key autoincrement,username varchar(20),password varchar(20))";
       arg0.execSQL(sql);        
    }

    @Override
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2)
    {
        // TODO Auto-generated method stub
        
    }
      
}

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//自定义ContentProvider，重写必须的方法，完成对数据库的增删改查操作。

package com.example.content_provider_03;

import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;

public class MyContentProvider  extends ContentProvider
{
     private My_Db_Helper helper;
     private String table="reg";
    private static final int  QUERYCODE=1;
    private static final int  INSERTCODE=2;
    private static final int  UPDATECODE=3;
    private static final int  DELETECODE=4;
     private static UriMatcher mMatcher=new UriMatcher(UriMatcher.NO_MATCH);
    static 
    {
        mMatcher.addURI("com.qianfeng.ly", "insert", INSERTCODE);//插入的匹配码
        mMatcher.addURI("com.qianfeng.ly", "query", QUERYCODE);   //查询匹配码
        mMatcher.addURI("com.qianfeng.ly", "update", UPDATECODE);  //编辑匹配码
        mMatcher.addURI("com.qianfeng.ly", "delete", DELETECODE);  //删除匹配码
        
    }
    public int delete(Uri arg0, String arg1, String[] arg2)
    {
        int n=-1;
        if (mMatcher.match(arg0)==DELETECODE)
            {
                SQLiteDatabase db=helper.getWritableDatabase();
                 n=db.delete(table, arg1, arg2);
            }
        return n;
    }

    @Override
    public String getType(Uri arg0)
    {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public Uri insert(Uri arg0, ContentValues arg1)
    {
        if (mMatcher.match(arg0)==INSERTCODE)
            {
                
                SQLiteDatabase db=helper.getWritableDatabase();
                db.insert(table, null, arg1);
            }
        return null;
    }
     //重写的 方法里面并没有此方法，但是必须有此方法
    @Override
    public boolean onCreate()
    {
        
        
        helper=new My_Db_Helper(getContext());
        
        return false;
    }

    @Override
    public Cursor query(Uri arg0, String[] arg1, String arg2, String[] arg3,
            String arg4)
    {
        Cursor cursor=null;
        if (mMatcher.match(arg0)==QUERYCODE)
            {
                SQLiteDatabase db=helper.getWritableDatabase();
            cursor=    db.query(table, arg1, arg2, arg3, null, null, arg4);
                
            }
        
        return cursor;
    }

    @Override
    public int update(Uri arg0, ContentValues arg1, String arg2, String[] arg3)
    {
        int n=-1;
    if (mMatcher.match(arg0)==UPDATECODE)
        {
            SQLiteDatabase db=helper.getWritableDatabase();
             n=db.update(table, arg1, arg2, arg3);
        }
        return n;
    }
    
}

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//在MainActivity中完成对数据库的插入操作

package com.example.content_provider_03;

import android.os.Bundle;

import android.app.Activity;
import android.content.ContentValues;
import android.database.sqlite.SQLiteDatabase;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends Activity
{

    private EditText username,password;
    private My_Db_Helper helper;
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        username=(EditText)findViewById(R.id.username);
        password=(EditText)findViewById(R.id.password);
        helper=new My_Db_Helper(this);
    }
    public void RegH(View v)
    {
        ContentValues values=new ContentValues();
        SQLiteDatabase db=helper.getWritableDatabase();
        values.put("username", username.getText().toString());
        values.put("password", password.getText().toString());
        db.insert("reg", null, values);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

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//布局界面在这里就不再赘述了

  <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
  >
  <TextView 
      android:layout_marginTop="12dp"
      android:id="@+id/name"
      android:layout_height="wrap_content"
      android:layout_width="wrap_content"
      android:text="用户名："
      />
   <EditText 
       android:layout_toRightOf="@id/name"
       android:layout_marginRight="10dp"
       android:id="@+id/username"
       android:layout_height="wrap_content"
       android:layout_width="match_parent"
       android:hint="请输入用户名"
       />
   <TextView 
       android:layout_marginTop="12dp"
       android:id="@+id/word"
       android:layout_height="wrap_content"
       android:layout_width="wrap_content"
       android:text=" 密 码 ："
       android:layout_below="@id/name"
       />
     <EditText 
         android:layout_below="@id/name"
         android:id="@+id/password"
         android:layout_height="wrap_content"
         android:layout_width="match_parent"
         android:layout_toRightOf="@id/word"
         android:hint="请输入密码"
         />
     <Button 
         android:id="@+id/reg"
         android:layout_height="wrap_content"
         android:layout_width="wrap_content"
         android:text="注册"
         android:onClick="RegH"
         android:layout_below="@id/word"
     android:layout_centerHorizontal="true"
         />
RelativeLayout>

=============================================================================================

这是另一个APP

package com.example.content_resolver03;

import java.util.ArrayList;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.net.Uri;
import android.os.Bundle;
import android.R.integer;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.database.Cursor;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.widget.AdapterView.AdapterContextMenuInfo;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity  implements View.OnClickListener
{
    List>data;
    ListView listView;
    TextView show_no;
    String quertUri="content://com.qianfeng.ly/query";
    String insertUri="content://com.qianfeng.ly/insert";
    String updateUri="content://com.qianfeng.ly/update";
    String deleteUri="content://com.qianfeng.ly/delete";
    private AlertDialog edDialog,delDialog;
    private EditText ed_name,ed_password;
    int position;//获得所点击的ListView的位置。
    ContentResolver resolver;
    private Button bn1,bn2;
    boolean flag=true;//设置一个标志位 ，确定是进行添加还是编辑；因为要共用一个对话框
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bn1=(Button)findViewById(R.id.queryBn);
        bn2=(Button)findViewById(R.id.insertBn);
        bn1.setOnClickListener(this);
        bn2.setOnClickListener(this);
        initView();
        registerForContextMenu(listView);//为选中的listView注册菜单选项
        resolver=getContentResolver();
        initDialog();
    }
  public void initView()
  {
      listView=(ListView)findViewById(R.id.mylist);
      show_no=(TextView)findViewById(R.id.show_no);
      listView.setEmptyView(show_no);
  }
  //为搜索和添加按钮设置监听事件 这两个按钮不需要设置对话框；
  public void onClick(View v)
  {
      switch (v.getId())
        {
        case R.id.queryBn:
             queryData();//列出所有项
            break;
        case R.id.insertBn:
            
            flag=true;
            ed_name.setText("");
            ed_password.setText("");
            edDialog.show();//使添加或者编辑对话框显示
            break;

        default:
            break;
        }
  }
    public void initDialog()
    {
        View view=getLayoutInflater().inflate(R.layout.dialog_item, null);
        ed_name=(EditText)view.findViewById(R.id.ed_name);
        ed_password=(EditText)view.findViewById(R.id.ed_password);
        //编辑和添加对话框
        edDialog=new AlertDialog.Builder(this).setIcon(android.R.drawable.ic_menu_add).setTitle("编辑联系人")
                .setView(view).setPositiveButton("确定",new OnClickListener()
                {
                    public void onClick(DialogInterface arg0, int arg1)
                    {
                        if (flag)
                            {
                                insertData();
                            }else {
                                updateData();
                            }
                        
                    }
                }).setNegativeButton("取消", null).create();
         //删除对话框
        delDialog=new AlertDialog.Builder(this).setIcon(android.R.drawable.ic_menu_delete).setTitle("确定要删除吗")
                .setPositiveButton("确定", new OnClickListener()
                {
                    public void onClick(DialogInterface arg0, int arg1)
                    {
                        deleteData();
                    }
                }).setNegativeButton("取消", null).create();
          
    }
  //菜单选项  长按会出现 编辑||删除选项，并跳转到相应的界面。
      @Override
    public void onCreateContextMenu(ContextMenu menu, View v,
            ContextMenuInfo menuInfo)
    {
        //获得菜单所对应的 XML文件
        getMenuInflater().inflate(R.menu.main,menu);
        position=((AdapterContextMenuInfo)menuInfo).position;
        super.onCreateContextMenu(menu, v, menuInfo);
    }
      @Override
    public boolean onContextItemSelected(MenuItem item)
    {
        //为选中的菜单选型设置监听事件。
        switch (item.getItemId())
            {
            case R.id.update:
                flag=false;
                edDialog.show();
                Mapmap=data.get(position);
                ed_name.setText(map.get("username").toString());
                ed_password.setText(map.get("password").toString());
                
                break;
            case  R.id.delete:
                delDialog.show();
                break;
            default:
                break;
            }
        
        return super.onContextItemSelected(item);
    }
    
      
      public void queryData()
      {
          //对数据库内的数据进行搜索 ，当然  仅仅局限于将所有项以列表的形式列出来
          Cursor cursor= resolver.query(Uri.parse(quertUri), null, null, null, null);
          data=CursorToList(cursor);
          SimpleAdapter adapter=new SimpleAdapter(this, data, R.layout.list_item, new String []{"username","password"}, new int[]{R.id.tv_name,R.id.tv_password});
          listView.setAdapter(adapter);
      }
      public void insertData()
      {
          ContentValues values=new ContentValues();
          values.put("username", ed_name.getText().toString());
          values.put("password", ed_password.getText().toString());
          resolver.insert(Uri.parse(insertUri), values);
          queryData();
      }
      //编辑数据；
      public void updateData()
      {
          String id=data.get(position).get("_id").toString();
          ContentValues values=new ContentValues();
          values.put("username", ed_name.getText().toString());
          values.put("password", ed_password.getText().toString());
          int  n=resolver.update(Uri.parse(updateUri), values, "_id=?", new String []{id});
          if (n>0)
            {
                Toast.makeText(this, "编辑成功", 1).show();
            }
          queryData();//更新数据库
      }
       //删除数据：
        public void deleteData()
        {
            String id=data.get(position).get("_id").toString();
            ContentValues values=new ContentValues();
             values.put("username", ed_name.getText().toString());
             values.put("password", ed_password.getText().toString());
             int n=resolver.delete(Uri.parse(deleteUri), "_id=?", new String[]{id});
             if (n>0)
                {
                    Toast.makeText(this, "删除成功", 1).show();
                }
             queryData();//更新数据库；
        }
      //将 得到的游标项转化成list
      public List> CursorToList(Cursor cursor)
      {
          List>list=new ArrayList>();
          ContentValues values=new ContentValues();
          while(cursor.moveToNext())
              {
                  Mapmap=new HashMap();
                  map.put("_id", cursor.getInt(cursor.getColumnIndex("_id")));
                  map.put("username", cursor.getString(cursor.getColumnIndex("username")));
                  map.put("password", cursor.getString(cursor.getColumnIndex("password")));
                  list.add(map);
              }
          return list;
      }
}

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接下来的是三个布局页面。

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
   >
   <LinearLayout 
       android:id="@+id/line"
       android:layout_height="wrap_content"
       android:layout_width="match_parent"
       android:orientation="horizontal"
       >
        <Button 
      android:id="@+id/queryBn"
      android:layout_height="wrap_content"
      android:layout_width="wrap_content"
      android:text="用我搜搜吧"
      />
      <Button 
          android:id="@+id/insertBn"
          android:layout_height="wrap_content"
          android:layout_width="wrap_content"
          android:text="没有东西加一点吧"
          />
   LinearLayout>
       <ListView 
           android:id="@+id/mylist"
           android:layout_height="match_parent"
           android:layout_width="match_parent"
          
           >ListView>
       <TextView 
           android:id="@+id/show_no"
           android:layout_height="match_parent"
           android:layout_width="match_parent"
           android:gravity="center"
           android:text="什么都没有哇"
           />
LinearLayout>

。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。

xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <EditText 
        android:id="@+id/ed_name"
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:hint="请输入用户名"
        
        />
    <EditText 
        android:id="@+id/ed_password"
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:hint="请输入密码"
        
        />

LinearLayout>

。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。

xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    
      <TextView 
          android:id="@+id/tv_name"
          android:layout_height="wrap_content"
          android:layout_width="match_parent"
          android:text="一遍不行，就来无数遍"
          android:gravity="center"
          />
      <TextView 
          android:id="@+id/tv_password"
          android:layout_height="wrap_content"
          android:layout_width="match_parent"
          android:text="不是运气不好，而是差一点努力"
          android:gravity="center"
          />
LinearLayout>

 

转载于:https://www.cnblogs.com/V1ncent/p/4856286.html