Regular Expression for ContentProvider's Uri's

Anm · by **Anm** » Sat Oct 18, 2008 10:10 pm

This RegEx should deal with a standard content:// Uri, separating out type string, instance id, and arguments into different groups.

Syntax: [ Download ] [ Hide ]

Using java Syntax Highlighting

 
StringBuffer sb = new StringBuffer();
 
sb.append( "\\A" );                               // Start of input
 
sb.append( "content://"+URI_AUTHORITY );          // content://provider
 
sb.append( "/(type1|type2|type/with/subtype)" );  // First path segment should be a recognized type (in a capture group)
 
sb.append( "(?:/(\\d*))?");                       // Optional second path segment should be digits (in a capture group)
 
sb.append( "/?");                                 // Optional end path separator
 
sb.append( "(?:\\?(.*))?" );                      // Optional argument list (in a capture group) prefixed with '?'
 
sb.append( "\\Z" );                               // End of input
 
Pattern regex = Pattern.compile( sb.toString(), Pattern.CASE_INSENSITIVE );
 
Parsed in 0.034 seconds,  using GeSHi 1.0.8.4

Why? My app's single ContentProvider supports several types, kinda like the Contacts app. This seemed easier than digging into the pre-parsed URI with lots of nested if/else statements. Using this, I can quickly check if the URI matches and pull out the informative data in a single pass. It also allowed me to be more flexible in my inputs (ending path separators, etc.).

Usage Example 1: getType(..):

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@Override
 
public String getType( Uri uri ) {
 
        Matcher matcher = URI_PATTERN.matcher( uri.toString() );
 
        String mime_type = null;
 
        if( matcher.matches() ) {
 
                String type = matcher.group( 1 ).toLowerCase();
 
                boolean has_ref_id = (matcher.group( 2 )!=null);
 
                if( "task".equals( type ) ) {
 
                        if( has_ref_id ) {
 
                                mime_type = MIME_TYPE_TASK;
 
                        } else {
 
                                mime_type = MIME_TYPE_TASKS;
 
                        }
 
                }  // else.. test against other types
 
        }
 
        return mime_type;
 
}
 
Parsed in 0.033 seconds,  using GeSHi 1.0.8.4

Usage Example 2: query(..):

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Using java Syntax Highlighting

 
@Override
 
public Cursor query(
 
                Uri uri,
 
                String[] projection,
 
                String selection,
 
                String[] selectionArgs,
 
                String sortOrder
 
) {
 
        Cursor cursor = null;
 
        Matcher matcher = URI_PATTERN.matcher( uri.toString() );
 
        if( matcher.matches() ) {
 
                String type = matcher.group( 1 ).toLowerCase();
 
                String ref_id = matcher.group( 2 );
 
                String uri_args = matcher.group( 3 );
 
                if( "task".equals( type ) ) {
 
                        cursor = queryTask( ref_id, uri_args, projection, selection, selectionArgs, sortOrder );
 
                }  // else.. test against other types
 
        }
 
        return cursor;
 
}
 
Parsed in 0.036 seconds,  using GeSHi 1.0.8.4

One thing you might consider changing is making the reference id mutually exclusive with the selection arguments.

Anm · by **Anm** » Fri Oct 24, 2008 7:47 am

Silly me. I just found the UriMatcher.

Regular Expression for ContentProvider's Uri's

Regular Expression for ContentProvider's Uri's

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