Android ContentProvider使用

近来使用下项目上用的不多的东西在自己的app，记录下遇到的问题：
项目地址：码云

在AndroidManifest.xml添加provider时，权限问题。添加android:permission=”…”,这样控制其他app访问权限使app更加安全，permission是允许读写权限，writepermission是允许写权限，readpermission是允许读权限

<provider
            android:name="com.bobbygu.bobbyapp.function.contentprovider.TeacherContentProvider"
            android:authorities="com.bobbygu.contentProvider"
            android:exported="true"
            android:multiprocess="false"
            android:permission="com.bobbygu.permission.CONTENTPROVIDER" />

然后在 application 外面添加下面代码

<permission
        android:name="com.bobbygu.permission.CONTENTPROVIDER"
        android:label="Allow read content provider"
        android:protectionLevel="normal" />

Service同样可以这样设置权限

<service
            android:name="com.bobbygu.bobbyapp.function.aidlSample.AIDLService"
            android:enabled="true"
            android:exported="true"
            android:permission="com.bobbygu.permission.CONTENTPROVIDER">
            <intent-filter>
                <action android:name="com.bobby.aidl.BobbyService" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </service>

在第二个app的Manifest中需要添加

<uses-permission android:name="com.bobbygu.permission.CONTENTPROVIDER"/>

获取contentprovider需要的权限

然后应用就可以开始使用contentProvider获取更新数据了

class ContentProviderTestActivity : AppCompatActivity(), View.OnClickListener {
    private var uri = Uri.parse("content://com.bobbygu.contentProvider/teacher")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_content_provider_test)
        btn_insert.setOnClickListener(this)
        btn_query.setOnClickListener(this)
        btn_query_all.setOnClickListener(this)
        btn_modify.setOnClickListener(this)
        btn_delete.setOnClickListener(this)
    }

    override fun onClick(v: View?) {
        when (v?.id) {
            R.id.btn_insert -> {
                val cv = ContentValues()
                cv.put("title", "jiaoshou")
                cv.put("name", "jiaoshi")
                cv.put("sex", true)
                val uri2 = contentResolver.insert(uri, cv)
                SweetAlertDialog(this)
                        .setTitleText(getString(R.string.dialog_title))
                        .setContentText(uri2.toString())
                        .show()
                Logger.d(uri2.toString())
            }
            R.id.btn_query -> {
                // 查找id为1的数据
                val c = contentResolver.query(uri, null, "_ID=?", arrayOf("1"), null)
                //这里必须要调用 c.moveToFirst将游标移动到第一条数据,不然会出现index -1 requested , with a size of 1错误；cr.query返回的是一个结果集。
                if (!c!!.moveToFirst()) {
                    // 为空的Cursor
                    SweetAlertDialog(this, SweetAlertDialog.ERROR_TYPE)
                            .setTitleText(getString(R.string.dialog_title))
                            .setContentText("未找到id=1的数据")
                            .show()
                    return
                }
                val name = c.getColumnIndex("name")
                Logger.d(c.getString(name))
                SweetAlertDialog(this)
                        .setTitleText(getString(R.string.dialog_title))
                        .setContentText(c.getString(name))
                        .show()
                c.close()
            }
            R.id.btn_query_all -> {
                val c = contentResolver.query(uri, null, null, null, null)
                var str = ""
                while (c.moveToNext()) {
                    str += c.getInt(c.getColumnIndex("_id")).toString() + "\n"
                }
                Logger.d("count:${c!!.count} \n$str")
                SweetAlertDialog(this)
                        .setTitleText(getString(R.string.dialog_title))
                        .setContentText("count:${c.count} \n$str")
                        .show()
                c.close()
            }
            R.id.btn_modify -> {
                val cv = ContentValues()
                cv.put("name", "huangbiao")
                cv.put("date_added", Date().toString())
                val updatedNum = contentResolver.update(uri, cv, "_ID=?", arrayOf("3"))
                println("updated" + ":" + updatedNum)
                if (updatedNum == 0)
                    SweetAlertDialog(this, SweetAlertDialog.ERROR_TYPE)
                            .setTitleText(getString(R.string.dialog_title))
                            .setContentText("数据更新失败")
                            .show()
                else
                    SweetAlertDialog(this)
                            .setTitleText(getString(R.string.dialog_title))
                            .setContentText("updated" + ":" + updatedNum)
                            .show()
            }
            R.id.btn_delete -> {
                val c = contentResolver.query(uri, null, null, null, null)
                if (!c!!.moveToFirst()) {
                    SweetAlertDialog(this, SweetAlertDialog.ERROR_TYPE)
                            .setTitleText(getString(R.string.dialog_title))
                            .setContentText("数据删除失败")
                            .show()
                    return
                }
                val index = c.getInt(c.getColumnIndex("_id")).toString()
                contentResolver.delete(uri, "_ID=?", arrayOf(index))
                SweetAlertDialog(this, SweetAlertDialog.SUCCESS_TYPE)
                        .setTitleText(getString(R.string.dialog_title))
                        .setContentText("btn_delete index:$index")
                        .show()
                c.close()
            }
        }
    }

    companion object {
        fun startActivity(activity: Activity) {
            activity.startActivity(Intent(activity, ContentProviderTestActivity::class.java))
        }
    }
}