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UriMatcher.javaAPI DocAndroid 1.5 API8937Wed May 06 22:41:54 BST 2009android.content

UriMatcher

public class UriMatcher extends Object
Utility class to aid in matching URIs in content providers.

To use this class, build up a tree of UriMatcher objects. Typically, it looks something like this: 

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();

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);
}

Then when you need to match match against a URI, call {@link #match}, providing the tokenized url you've been given, and the value you want if there isn't a match. You can use the result to build a query, return a type, insert or delete a row, or whatever you need, without duplicating all of the if-else logic you'd otherwise need. Like this: 

public String getType(String[] url)
{
int match = sURIMatcher.match(url, NO_MATCH);
switch (match)
{
case PEOPLE:
return "vnd.android.cursor.dir/person";
case PEOPLE_ID:
return "vnd.android.cursor.item/person";
... snip ...
return "vnd.android.cursor.dir/snail-mail";
case PEOPLE_ADDRESS_ID:
return "vnd.android.cursor.item/snail-mail";
default:
return null;
}
}
instead of 
public String getType(String[] url)
{
if (url.length >= 2) {
if (url[1].equals("people")) {
if (url.length == 2) {
return "vnd.android.cursor.dir/person";
} else if (url.length == 3) {
return "vnd.android.cursor.item/person";
... snip ...
return "vnd.android.cursor.dir/snail-mail";
} else if (url.length == 3) {
return "vnd.android.cursor.item/snail-mail";
}
}
}
return null;
}

Fields Summary
public static final int
NO_MATCH
static final Pattern
PATH_SPLIT_PATTERN
private static final int
EXACT
private static final int
NUMBER
private static final int
TEXT
private int
mCode
private int
mWhich
private String
mText
private ArrayList
mChildren
Constructors Summary
public UriMatcher(int code)
Creates the root node of the URI tree.

param
code the code to match for the root URI

                           
      
    
        mCode = code;
        mWhich = -1;
        mChildren = new ArrayList<UriMatcher>();
        mText = null;
private UriMatcher()

        mCode = NO_MATCH;
        mWhich = -1;
        mChildren = new ArrayList<UriMatcher>();
        mText = null;
Methods Summary
public voidaddURI(java.lang.String authority, java.lang.String path, int code)
Add a URI to match, and the code to return when this URI is matched. URI nodes may be exact match string, the token "*" that matches any text, or the token "#" that matches only numbers.

param
authority the authority to match
param
path the path to match. * may be used as a wild card for any text, and # may be used as a wild card for numbers.
param
code the code that is returned when a URI is matched against the given components. Must be positive.

        if (code < 0) {
            throw new IllegalArgumentException("code " + code + " is invalid: it must be positive");
        }
        String[] tokens = path != null ? PATH_SPLIT_PATTERN.split(path) : null;
        int numTokens = tokens != null ? tokens.length : 0;
        UriMatcher node = this;
        for (int i = -1; i < numTokens; i++) {
            String token = i < 0 ? authority : tokens[i];
            ArrayList<UriMatcher> children = node.mChildren;
            int numChildren = children.size();
            UriMatcher child;
            int j;
            for (j = 0; j < numChildren; j++) {
                child = children.get(j);
                if (token.equals(child.mText)) {
                    node = child;
                    break;
                }
            }
            if (j == numChildren) {
                // Child not found, create it
                child = new UriMatcher();
                if (token.equals("#")) {
                    child.mWhich = NUMBER;
                } else if (token.equals("*")) {
                    child.mWhich = TEXT;
                } else {
                    child.mWhich = EXACT;
                }
                child.mText = token;
                node.mChildren.add(child);
                node = child;
            }
        }
        node.mCode = code;
public intmatch(android.net.Uri uri)
Try to match against the path in a url.

param
uri The url whose path we will match against.
return
The code for the matched node (added using addURI), or -1 if there is no matched node.


                                                      
       
    
        final int li = uri.getPathSegments().size();

        UriMatcher node = this;

        if (li == 0 && uri.getAuthority() == null) {
            return this.mCode;
        }

        for (int i=-1; i<li; i++) {
            String u = i < 0 ? uri.getAuthority() : uri.getPathSegments().get(i);
            ArrayList<UriMatcher> list = node.mChildren;
            if (list == null) {
                break;
            }
            node = null;
            int lj = list.size();
            for (int j=0; j<lj; j++) {
                UriMatcher n = list.get(j);
          which_switch:
                switch (n.mWhich) {
                    case EXACT:
                        if (n.mText.equals(u)) {
                            node = n;
                        }
                        break;
                    case NUMBER:
                        int lk = u.length();
                        for (int k=0; k<lk; k++) {
                            char c = u.charAt(k);
                            if (c < '0" || c > '9") {
                                break which_switch;
                            }
                        }
                        node = n;
                        break;
                    case TEXT:
                        node = n;
                        break;
                }
                if (node != null) {
                    break;
                }
            }
            if (node == null) {
                return NO_MATCH;
            }
        }

        return node.mCode;