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Android中Uri的使用

發(fā)布時(shí)間：2025/4/5 Android 45 豆豆

生活随笔收集整理的這篇文章主要介紹了 Android中Uri的使用小編覺(jué)得挺不錯(cuò)的,現(xiàn)在分享給大家,幫大家做個(gè)參考.

1.Uri

通用資源標(biāo)志符（Universal Resource Identifier, 簡(jiǎn)稱"URI"）。

Uri代表要操作的數(shù)據(jù)，Android上可用的每種資源 - 圖像、視頻片段等都可以用Uri來(lái)表示。

URI一般由三部分組成：

，URI主要分三個(gè)部分：scheme, authority and path。其中authority又分為host和port。格式如下：

scheme://host:port/path
舉個(gè)實(shí)際的例子：
content://com.example.project:200/folder/subfolder/etc
\---------/? \---------------------------/ \---/ \--------------------------/
scheme???????????????? host?????????????? port??????? path
??????????????? \--------------------------------/
????????????????????????? authority? ?

現(xiàn)在大家應(yīng)該知道data flag中那些屬性的含義了吧，看下data flag
<data android:host="string"
????? android:mimeType="string"
????? android:path="string"
????? android:pathPattern="string"
????? android:pathPrefix="string"
????? android:port="string"
????? android:scheme="string" />
但是我們?cè)诔绦蛑幸话闶遣恢苯佑肬RI來(lái)標(biāo)識(shí)CP的，是的，正如我們通常見(jiàn)到的用定義的常量來(lái)標(biāo)識(shí)。例如standard CP中的Contacts，我們就用Contacts.People.CONTENT_URI來(lái)標(biāo)識(shí)Contacts CP中People這個(gè)表。那么要標(biāo)識(shí)某個(gè)具體的人怎么辦呢？這就用到了ContentUris.withAppendedId() 和 Uri.withAppendedPath()。例如我們要表示content://contacts/people/20，那么我們就可以用如下語(yǔ)句：
Uri uri = ContentUris.withAppendedId(People.CONTENT_URI, 20); 或者
Uri uri = Uri.withAppendedPath(People.CONTENT_URI, "20");

訪問(wèn)資源的命名機(jī)制。?

存放資源的主機(jī)名。?

資源自身的名稱，由路徑表示。?

Android的Uri由以下三部分組成： "content://"、數(shù)據(jù)的路徑、標(biāo)示ID(可選)

舉些例子，如：?

所有聯(lián)系人的Uri： content://contacts/people

某個(gè)聯(lián)系人的Uri: content://contacts/people/5

所有圖片Uri: content://media/external

某個(gè)圖片的Uri：content://media/external/images/media/4

我們很經(jīng)常需要解析Uri，并從Uri中獲取數(shù)據(jù)。

Android系統(tǒng)提供了兩個(gè)用于操作Uri的工具類，分別為UriMatcher 和ContentUris 。

雖然這兩類不是非常重要，但是掌握它們的使用，會(huì)便于我們的開發(fā)工作。

下面就一起看一下這兩個(gè)類的作用。

2.UriMatcher

UriMatcher 類主要用于匹配Uri.

使用方法如下。

首先第一步，初始化：

UriMatcher?matcher?=?new?UriMatcher(UriMatcher.NO_MATCH);??

UriMatcher?matcher?=?new?UriMatcher(UriMatcher.NO_MATCH);??

第二步注冊(cè)需要的Uri:

matcher.addURI("com.yfz.Lesson",?"people",?PEOPLE);??
matcher.addURI("com.yfz.Lesson",?"person/#",?PEOPLE_ID);??

matcher.addURI("com.yfz.Lesson",?"people",?PEOPLE);??
matcher.addURI("com.yfz.Lesson",?"person/#",?PEOPLE_ID);??

第三部，與已經(jīng)注冊(cè)的Uri進(jìn)行匹配:

Uri?uri?=?Uri.parse("content://"?+?"com.yfz.Lesson"?+?"/people");??
int?match?=?matcher.match(uri);??
???????switch?(match)??
???????{??
???????????case?PEOPLE:??
???????????????return?"vnd.Android.cursor.dir/people";??
???????????case?PEOPLE_ID:??
???????????????return?"vnd.android.cursor.item/people";??
???????????default:??
???????????????return?null;??
???????}??

Uri?uri?=?Uri.parse("content://"?+?"com.yfz.Lesson"?+?"/people");??
int?match?=?matcher.match(uri);??
???????switch?(match)??
???????{??
???????????case?PEOPLE:??
???????????????return?"vnd.Android.cursor.dir/people";??
???????????case?PEOPLE_ID:??
???????????????return?"vnd.Android.cursor.item/people";??
???????????default:??
???????????????return?null;??
???????}??

match方法匹配后會(huì)返回一個(gè)匹配碼Code，即在使用注冊(cè)方法addURI時(shí)傳入的第三個(gè)參數(shù)。?

上述方法會(huì)返回"vnd.Android.cursor.dir/person".?

總結(jié):?

--常量 UriMatcher.NO_MATCH 表示不匹配任何路徑的返回碼

--# 號(hào)為通配符

--* 號(hào)為任意字符?

另外說(shuō)一下，官方SDK說(shuō)明中關(guān)于Uri的注冊(cè)是這樣寫的：

private?static?final?UriMatcher?sURIMatcher?=?new?UriMatcher();??
????static??
????{??
????????sURIMatcher.addURI("contacts",?"/people",?PEOPLE);??
????????sURIMatcher.addURI("contacts",?"/people/#",?PEOPLE_ID);??
????????sURIMatcher.addURI("contacts",?"/people/#/phones",?PEOPLE_PHONES);??
????????sURIMatcher.addURI("contacts",?"/people/#/phones/#",?PEOPLE_PHONES_ID);??
????????sURIMatcher.addURI("contacts",?"/people/#/contact_methods",?PEOPLE_CONTACTMETHODS);??
????????sURIMatcher.addURI("contacts",?"/people/#/contact_methods/#",?PEOPLE_CONTACTMETHODS_ID);??
????????sURIMatcher.addURI("contacts",?"/deleted_people",?DELETED_PEOPLE);??
????????sURIMatcher.addURI("contacts",?"/phones",?PHONES);??
????????sURIMatcher.addURI("contacts",?"/phones/filter/",?PHONES_FILTER);??
????????sURIMatcher.addURI("contacts",?"/phones/#",?PHONES_ID);??
????????sURIMatcher.addURI("contacts",?"/contact_methods",?CONTACTMETHODS);??
????????sURIMatcher.addURI("contacts",?"/contact_methods/#",?CONTACTMETHODS_ID);??
????????sURIMatcher.addURI("call_log",?"/calls",?CALLS);??
????????sURIMatcher.addURI("call_log",?"/calls/filter/",?CALLS_FILTER);??
????????sURIMatcher.addURI("call_log",?"/calls/#",?CALLS_ID);??
????}??

private?static?final?UriMatcher?sURIMatcher?=?new?UriMatcher();??
????static??
????{??
????????sURIMatcher.addURI("contacts",?"/people",?PEOPLE);??
????????sURIMatcher.addURI("contacts",?"/people/#",?PEOPLE_ID);??
????????sURIMatcher.addURI("contacts",?"/people/#/phones",?PEOPLE_PHONES);??
????????sURIMatcher.addURI("contacts",?"/people/#/phones/#",?PEOPLE_PHONES_ID);??
????????sURIMatcher.addURI("contacts",?"/people/#/contact_methods",?PEOPLE_CONTACTMETHODS);??
????????sURIMatcher.addURI("contacts",?"/people/#/contact_methods/#",?PEOPLE_CONTACTMETHODS_ID);??
????????sURIMatcher.addURI("contacts",?"/deleted_people",?DELETED_PEOPLE);??
????????sURIMatcher.addURI("contacts",?"/phones",?PHONES);??
????????sURIMatcher.addURI("contacts",?"/phones/filter/",?PHONES_FILTER);??
????????sURIMatcher.addURI("contacts",?"/phones/#",?PHONES_ID);??
????????sURIMatcher.addURI("contacts",?"/contact_methods",?CONTACTMETHODS);??
????????sURIMatcher.addURI("contacts",?"/contact_methods/#",?CONTACTMETHODS_ID);??
????????sURIMatcher.addURI("call_log",?"/calls",?CALLS);??
????????sURIMatcher.addURI("call_log",?"/calls/filter/",?CALLS_FILTER);??
????????sURIMatcher.addURI("call_log",?"/calls/#",?CALLS_ID);??
????}???

這個(gè)說(shuō)明估計(jì)已經(jīng)是Google官方?jīng)]有更新，首先是初始化方法，沒(méi)有傳參，那么現(xiàn)在初始化時(shí)，實(shí)際是必須傳參的。可以看一下Android2.2的源碼，無(wú)參數(shù)的構(gòu)造方法已經(jīng)是private的了。

另外就是addURI這個(gè)方法，第二個(gè)參數(shù)開始時(shí)不需要"/"，否則是無(wú)法匹配成功的。

3.ContentUris

ContentUris 類用于獲取Uri路徑后面的ID部分

1)為路徑加上ID: withAppendedId(uri, id)

比如有這樣一個(gè)Uri

Uri?uri?=?Uri.parse("content://com.yfz.Lesson/people")??

Uri?uri?=?Uri.parse("content://com.yfz.Lesson/people")??

通過(guò)withAppendedId方法，為該Uri加上ID

Uri?resultUri?=?ContentUris.withAppendedId(uri,?10);??

Uri?resultUri?=?ContentUris.withAppendedId(uri,?10);??

最后resultUri為: content://com.yfz.Lesson/people/10

2)從路徑中獲取ID: parseId(uri)

Uri?uri?=?Uri.parse("content://com.yfz.Lesson/people/10")??
long?personid?=?ContentUris.parseId(uri);??

Uri?uri?=?Uri.parse("content://com.yfz.Lesson/people/10")??
long?personid?=?ContentUris.parseId(uri);??

最后personid 為 :10?

附上實(shí)驗(yàn)的代碼：

package?com.yfz;??
import?com.yfz.log.Logger;??
import?Android.app.Activity;??
import?android.content.ContentUris;??
import?android.content.UriMatcher;??
import?android.net.Uri;??
import?android.os.Bundle;??
public?class?Lesson_14?extends?Activity?{??
??????????
????????private?static?final?String?AUTHORITY?=?"com.yfz.Lesson";??
????????private?static?final?int?PEOPLE?=?1;??
????????private?static?final?int?PEOPLE_ID?=?2;??
??????????
????????//NO_MATCH表示不匹配任何路徑的返回碼??
????????private?static?final?UriMatcher?sURIMatcher?=?new?UriMatcher(UriMatcher.NO_MATCH);??
????????static??
????????{??
????????????sURIMatcher.addURI(AUTHORITY,?"people",?PEOPLE);??
??????????????
????????????//這里的#代表匹配任意數(shù)字，另外還可以用*來(lái)匹配任意文本??
????????????sURIMatcher.addURI(AUTHORITY,?"people/#",?PEOPLE_ID);??
????????}??
??????????
????????@Override??
????????protected?void?onCreate(Bundle?savedInstanceState)?{??
????????????super.onCreate(savedInstanceState);??
????????????Logger.d("------?Start?Activity?!!!?------");??
??????????????
????????????Uri?uri1?=?Uri.parse("content://"?+?AUTHORITY?+?"/people");??
????????????Logger.e("Uri:"?+?uri1);??
????????????Logger.d("Match?1"?+?getType(uri1));??
??????????????
????????????Uri?uri2?=?Uri.parse("content://"?+?AUTHORITY?+?"/people"?+?"/2");??
??????????????
????????????Logger.e("Uri:"?+?uri2);??
????????????Logger.d("Match?2"?+?getType(uri2));??
??????????????
????????????//拼接Uri??
????????????Uri?cUri?=?ContentUris.withAppendedId(uri1,?15);??
????????????Logger.e("Uri:"?+?cUri);??
????????????//獲取ID??
????????????long?id?=?ContentUris.parseId(cUri);??
????????????Logger.d("Uri?ID:?"?+?id);??
????????}??
??????????
????????private?String?getType(Uri?uri)?{??
????????????int?match?=?sURIMatcher.match(uri);??
????????????switch?(match)??
????????????{??
????????????????case?PEOPLE:??
????????????????????return?"vnd.android.cursor.dir/person";??
????????????????case?PEOPLE_ID:??
????????????????????return?"vnd.android.cursor.item/person";??
????????????????default:??
????????????????????return?null;??? }??????? } }?

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