android源代码在  彩信sms 表和彩信 pdu表，增加了一个触发器

CREATE TRIGGER delete_obsolete_threads_pdu AFTER 
DELETE ON pdu BEGIN   
DELETE FROM threads   
WHERE     _id = old.thread_id     AND _id NOT IN    (SELECT thread_id FROM sms      UNION SELECT thread_id from pdu);END

仔细看下就明白，如果threads表没有sms和pdu外部引用的时候，这条thread就会被删除。

thread被删除后，你再插入一条短信或者彩信（当然是代码插入），这时候因为没有thread id，所以就会不显示。

有人可能想到对threads表一起进行维护不就行了吗？  很不幸 ，系统对这个表的providers并不完全开放，只能用于查找。

但我们这时候又需要thread_id,   我对源代码进行了一些修改，把thread类提取了出来，仅供大家参考

package com.sweetop.provider;import java.util.HashSet;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.text.TextUtils;
import android.util.Log;
import android.util.Patterns;public final class Threads implements ThreadsColumns {private static final String[] ID_PROJECTION = { BaseColumns._ID };private static final String STANDARD_ENCODING = "UTF-8";private static final Uri THREAD_ID_CONTENT_URI = Uri.parse("content://mms-sms/threadID");public static final Uri CONTENT_URI = Uri.withAppendedPath(Uri.parse("content://mms-sms/"), "conversations");public static final Uri OBSOLETE_THREADS_URI = Uri.withAppendedPath(CONTENT_URI, "obsolete");public static final Pattern NAME_ADDR_EMAIL_PATTERN = Pattern.compile("\\s*(\"[^\"]*\"|[^<>\"]+)\\s*<([^<>]+)>\\s*");public static final int COMMON_THREAD = 0;public static final int BROADCAST_THREAD = 1;// No one should construct an instance of this class.private Threads() {}/*** This is a single-recipient version of getOrCreateThreadId. It's* convenient for use with SMS messages.*/public static long getOrCreateThreadId(Context context, String recipient) {Set<String> recipients = new HashSet<String>();recipients.add(recipient);return getOrCreateThreadId(context, recipients);}/*** Given the recipients list and subject of an unsaved message, return its* thread ID. If the message starts a new thread, allocate a new thread ID.* Otherwise, use the appropriate existing thread ID.* * Find the thread ID of the same set of recipients (in any order, without* any additions). If one is found, return it. Otherwise, return a unique* thread ID.*/public static long getOrCreateThreadId(Context context,Set<String> recipients) {Uri.Builder uriBuilder = THREAD_ID_CONTENT_URI.buildUpon();for (String recipient : recipients) {if (isEmailAddress(recipient)) {recipient = extractAddrSpec(recipient);}uriBuilder.appendQueryParameter("recipient", recipient);}Uri uri = uriBuilder.build();// if (DEBUG) Log.v(TAG, "getOrCreateThreadId uri: " + uri);Cursor cursor = context.getContentResolver().query(uri, ID_PROJECTION,null, null, null);if (true) {Log.v("Threads","getOrCreateThreadId cursor cnt: " + cursor.getCount());}if (cursor != null) {try {if (cursor.moveToFirst()) {return cursor.getLong(0);} else {Log.e("Threads", "getOrCreateThreadId returned no rows!");}} finally {cursor.close();}}Log.e("Threads","getOrCreateThreadId failed with uri " + uri.toString());throw new IllegalArgumentException("Unable to find or allocate a thread ID.");}public static String extractAddrSpec(String address) {Matcher match = NAME_ADDR_EMAIL_PATTERN.matcher(address);if (match.matches()) {return match.group(2);}return address;}/*** Returns true if the address is an email address* * @param address*            the input address to be tested* @return true if address is an email address*/public static boolean isEmailAddress(String address) {if (TextUtils.isEmpty(address)) {return false;}String s = extractAddrSpec(address);Matcher match = Patterns.EMAIL_ADDRESS.matcher(s);return match.matches();}
}

当你需要获得一个thread id时，仅需调用

Threads.getOrCreateThreadId(this, address)

address是发送方的手机地址

如有问题，可以再评论中说明，我会一一回复。

另，转载注明出处