Android中ContentProvider的简单使用

1、新建继承ContentProvider的类

package com.wangzhu.demo;

import android.content.ContentProvider;

import android.content.ContentValues;

import android.content.Context;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.net.Uri;

public class MyContentProvider extends ContentProvider {

    /**

     * ContentProvider的数据访问路径

     */

    public static final Uri URI = Uri.parse("content://com.wangzhu.provider");

    private SQLiteDatabase database;

    @Override

    public int delete(Uri arg0, String arg1, String[] arg2) {

        return 0;

    }

    @Override

    public String getType(Uri arg0) {

        return null;

    }

    @Override

    public Uri insert(Uri uri, ContentValues values) {

        database.insert("tab", "_id", values);

        return null;

    }

    @Override

    public boolean onCreate() {

        database = getContext().openOrCreateDatabase("myProvider.db3",

                Context.MODE_PRIVATE, null);

        database.execSQL("create table IF NOT EXISTS tab(_id INTEGER PRIMARY KEY AUTOINCREMENT,name TEXT NOT NULL)");

        return true;

    }

    @Override

    public Cursor query(Uri arg0, String[] arg1, String arg2, String[] arg3,

            String arg4) {

        Cursor cursor = database.query("tab", null, null, null, null, null,

                null);

        return cursor;

    }

    @Override

    public int update(Uri arg0, ContentValues arg1, String arg2, String[] arg3) {

        return 0;

    }

}

2、在AndroidManifest.xml中为应用程序添加ContentProvider的访问权限

        <!-- android:exported设置为true，表示其他应用可以访问，否则不可以访问 -->

        <provider

            android:name="MyContentProvider"

            android:authorities="com.wangzhu.provider"

            android:exported="true" >

        </provider>

3、进行插入与查询

        final Uri uri = MyContentProvider.URI;

    /**

     * 往Provider中写入数据

     */

    protected void write() {

        //使用getContentResolver()方法获取ContentResolver对象

        ContentResolver resolver = getContentResolver();

        ContentValues values = null;

        values = new ContentValues();

        values.put("name", "Java");

        //调用ContentResolver对象的insert方法，插入数据

        resolver.insert(uri, values);

        values = new ContentValues();

        values.put("name", "Swift");

        resolver.insert(uri, values);

        values = new ContentValues();

        values.put("name", "Python");

        resolver.insert(uri, values);

        values = new ContentValues();

        values.put("name", "C#");

        resolver.insert(uri, values);

    }

    /**

     * 读取Provider中的内容

     */

    protected void read() {

        StringBuilder accum = new StringBuilder();

        //使用getContentResolver()方法获取ContentResolver对象

        //调用ContentResolver对象的query方法，查询数据，返回Cursor对象

        Cursor cursor = getContentResolver().query(uri, null, null, null, null);

        cursor.moveToFirst();

        for (int i = 0, count = cursor.getCount(); i < count; i++) {

            accum.append(cursor.getString(cursor.getColumnIndex("name")))

                    .append("\n");

            cursor.moveToNext();

        }

        System.err.println("read: " + accum);

    }