Android之URI

一、URI简介

URI包含如下几个部分：

content://usrname:[e-mail]:80/person/10

1、红色部分：访问资源的命名机制

2、绿色部分：存放资源的主机名，或称为authority

3、蓝色部分：资源本省的名称,由路径表示

二、URI类

android的URI类提供了几个使用接口来处理一个URI路径

1、public static final Uri EMPTY

一个空的URI对象，相等于""

2、public abstract String getAuthority ()

获取URI的authority部分，即usrname:[e-mail]:80

3、public abstract String getHost ()

获取URI的主机部分，即com.google.com

4、public abstract int getPort ()

获取URI的端口，即80

5、、public abstract String getScheme ()

获取URI的scheme，即content://

6、public abstract String getUserInfo ()

获取URI的用户信息，即usrname:password

三、UriMatcher类

android为URI提供了一个UriMatcher类，用来对URI进行各种匹配。其主要接口如下：

voidaddURI(String authority, String path, int code)
向该UriMatcher中添加一条匹配规则.authority如前所述；path为资源的路径，其中"*"可表示匹配任何字符，"#"表示匹配一个数字；code为当某一URI匹配该规则时，返回的匹配码
int match(Uri uri)
开始匹配一个URI，成功则返回前面设定的code，否则返回UriMatcher.NO_MATCH常量。

以下摘自android：

private static final int PEOPLE = 1;
private static final int PEOPLE_ID = 2;
private static final int PEOPLE_PHONES = 3;
private static final int PEOPLE_PHONES_ID = 4;
private static final int PEOPLE_CONTACTMETHODS = 7;
private static final int PEOPLE_CONTACTMETHODS_ID = 8;


private static final int DELETED_PEOPLE = 20;


private static final int PHONES = 9;
private static final int PHONES_ID = 10;
private static final int PHONES_FILTER = 14;


private static final int CONTACTMETHODS = 18;
private static final int CONTACTMETHODS_ID = 19;


private static final int CALLS = 11;
private static final int CALLS_ID = 12;
private static final int CALLS_FILTER = 15;


private static final UriMatcher sURIMatcher = new UriMatcher(UriMatcher.NO_MATCH);


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);
}

四、ContentUris类

ContentUris类是android提供的又一个URI的工具类，其作用主要是操作使用"content://"的URI路径后面的ID部分。其主要接口如下：

1、static Uri.BuilderappendId(Uri.Builder builder, long id)
将一个id添加到URI的后面.
2、static long parseId(Uri contentUri)
获取URI后面的路径id.
3、static Uri withAppendedId(Uri contentUri, long id)
类似于appendId，同样是将id添加到URI的后面.