安卓四大基本组件之一 ContentProvider（自定义内容提供者实例）

ContentPRovider将应用中的数据对其他应用进行共享，提供增删改查的方法

首先在数据提供者的demo创建一个类,继承ContentProvider

package com.provide;import android.content.ContentProvider;import android.content.ContentUris;import android.content.ContentValues;import android.content.UriMatcher;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.net.Uri;import android.support.annotation.Nullable;import android.util.Log;import db.DbHelper;/** * 内容提供者 * Created by yangyan on 2017/2/6. */public class mycontentprovide extends ContentProvider {    private DbHelper dbHelper;    private SQLiteDatabase sqLiteDatabase;    private UriMatcher uriMatcher;    @Override    public boolean onCreate() {        Log.i("test","onCreate");        //uri匹配器        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);        //查询所有规则        uriMatcher.addURI("com.example.android16_sqllite.PERSON","person",1);        //查询单个规则        uriMatcher.addURI("com.example.android16_sqllite.PERSON","person/#",2);        dbHelper = new DbHelper(getContext(),"person.db",null,2);        sqLiteDatabase = dbHelper.getReadableDatabase();        return false;    }    @Nullable    @Override    public Cursor query(Uri uri, String[] strings, String s, String[] strings1, String s1) {        Log.i("test","查询");        //根据匹配器匹配        int type=uriMatcher.match(uri);        switch (type) {            case 1:                //查询所有                Log.i("test","查询所有");                return sqLiteDatabase.query(false,"person",strings,s,strings1,null,null,s1,null);                case 2:                    //获取要查询的值                    long id=ContentUris.parseId(uri);                    Log.i("test","查询单个");                return sqLiteDatabase.query(false,"person",strings,"_id=?",new String[]{id+""},null,null,s1,null);        }        return null;    }    @Nullable    @Override    public String getType(Uri uri) {        Log.i("test","getType");        return null;    }    @Nullable    @Override    public Uri insert(Uri uri, ContentValues contentValues) {        Log.i("test","添加");        sqLiteDatabase.insert("person",null,contentValues);        return uri;    }    @Override    public int delete(Uri uri, String s, String[] strings) {        Log.i("test","删除");        return sqLiteDatabase.delete("person",s,strings);    }    @Override    public int update(Uri uri, ContentValues contentValues, String s, String[] strings) {        Log.i("test","修改");        return sqLiteDatabase.update("person",contentValues,s,strings);    }}
！需要在androidMainfest.xml配置ContentProvider （name为类名，authorities为包名.自定义明智）
 // 需在创建个内容访问的demo访问数据的测试类
package com.example.android24_contentprovide;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.text.TextUtils;import android.util.Log;import android.view.View;import android.widget.EditText;import android.widget.Toast;/** * 内容访问者 */public class MainActivity extends AppCompatActivity {    private ContentResolver contentResolver;    private EditText et_main_text;    private EditText et_main_text2;    private EditText et_main_text3;    private EditText et_main_text4;    private EditText et_main_text5;    private Cursor cursor;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        //获取内容访问者        contentResolver = getContentResolver();        initview();    }    //初始化控件    public void  initview(){        et_main_text = (EditText) findViewById(R.id.et_main_text);        et_main_text2 = (EditText) findViewById(R.id.et_main_text2);        et_main_text3 = (EditText) findViewById(R.id.et_main_text3);        et_main_text4 = (EditText) findViewById(R.id.et_main_text4);        et_main_text5 = (EditText) findViewById(R.id.et_main_text5);    }    //添加    public void add(View view){
 	  // 访问内容提供者          Uri  uri = Uri.parse("content://com.example.android16_sqllite.PERSON");        ContentValues contentValues = new ContentValues();        String name=et_main_text2.getText().toString();        int age=Integer.parseInt(et_main_text3.getText().toString());        contentValues.put("name",name);        contentValues.put("age",age);        contentResolver.insert(uri,contentValues);        Toast.makeText(this, "添加成功", Toast.LENGTH_SHORT).show();        Log.i("test","添加");    }    //修改    public void update(View view){
          // 访问内容提供者          Uri  uri = Uri.parse("content://com.example.android16_sqllite.PERSON");        ContentValues  contentValues = new ContentValues();        String name=et_main_text4.getText().toString();        int age=Integer.parseInt(et_main_text5.getText().toString());        contentValues.put("name",name);        contentValues.put("age",age);        contentResolver.update(uri,contentValues,"_id=?",new String[]{5+""});        Log.i("test","修改");        Toast.makeText(this, "修改成功", Toast.LENGTH_SHORT).show();    }    //删除    public void delete(View view){
        // 访问内容提供者          Uri uri = Uri.parse("content://com.example.android16_sqllite.PERSON");        contentResolver.delete(uri,"_id=?",new String[]{1+""});        Log.i("test","删除");        Toast.makeText(this, "删除成功", Toast.LENGTH_SHORT).show();    }    //查询    public void queryall(View view){        //判断输入框是否为空        Uri uri;        if(TextUtils.isEmpty(et_main_text.getText().toString())){        //内容协议：content://            uri = Uri.parse("content://com.example.android16_sqllite.PERSON/person");        }else{            String id=et_main_text.getText().toString();            //查询单个            uri = Uri.parse("content://com.example.android16_sqllite.PERSON/person/"+id);        }        //查询所有数据        cursor = contentResolver.query(uri,null,null,null,null);        while (cursor.moveToNext()){            int id= cursor.getInt(cursor.getColumnIndex("_id"));            String name= cursor.getString(cursor.getColumnIndex("name"));            int age= cursor.getInt(cursor.getColumnIndex("age"));            Log.i("test","id: "+id+"name: "+name+"age: "+age);        }    }}