Android 数据库 ANR的例子

android 开启事务之后，在其他线程是不能进行增删改查操作的。例子如下：

首先，一个线程里面去开启事务，里面对数据库的任何操作都没有。

		DBAdapter.getInstance().beginTransaction();
		long begin  = System.currentTimeMillis();
		int a = 50;
		while(System.currentTimeMillis() - begin < 1000 * 60 * 10){
			a=60;
		}

		DBAdapter.getInstance().setTransactionSuccessful();
		DBAdapter.getInstance().endTransaction();

第二步，主线程去查询数据库

                        cloudBook = DBAdapter.getInstance().queryBookIDWithoutPath(item.mBookID, item.mFile);

第三步，直接卡死

"main" prio=5 tid=1 TimedWaiting
  | group="main" sCount=1 dsCount=0 obj=0x7405e578 self=0xf5276500
  | sysTid=9309 nice=-4 cgrp=default sched=0/0 handle=0xf74c6b34
  | state=S schedstat=( 2038578573 87941787 1472 ) utm=184 stm=19 core=5 HZ=100
  | stack=0xff56c000-0xff56e000 stackSize=8MB
  | held mutexes=
  at java.lang.Object.wait!(Native method)
  - waiting on <0x0cc38bc3> (a java.lang.Object)
  at java.lang.Thread.parkFor$(Thread.java:1220)
  - locked <0x0cc38bc3> (a java.lang.Object)
  at sun.misc.Unsafe.park(Unsafe.java:299)
  at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:198)
  at android.database.sqlite.SQLiteConnectionPool.waitForConnection(SQLiteConnectionPool.java:670)
  at android.database.sqlite.SQLiteConnectionPool.acquireConnection(SQLiteConnectionPool.java:348)
  at android.database.sqlite.SQLiteSession.acquireConnection(SQLiteSession.java:894)
  at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:586)
  at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
  at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
  at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1674)
  at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1605)
  at com.zhangyue.iReader.DB.DBAdapter.execSQL(DBAdapter.java:2510)
  - locked <0x0faa1c40> (a com.zhangyue.iReader.DB.DBAdapter)
  at com.zhangyue.iReader.DB.DBAdapter.queryBookIDWithoutPath(DBAdapter.java:1497)
  at com.zhangyue.iReader.read.ui.BookBrowserFragment.isDisplayAddBookShelf(BookBrowserFragment.java:1223)
  at com.zhangyue.iReader.read.ui.BookBrowserFragment.access$5600(BookBrowserFragment.java:368)
  at com.zhangyue.iReader.read.ui.BookBrowserFragment$20.run(BookBrowserFragment.java:3098)
  at android.os.Handler.handleCallback(Handler.java:739)
  at android.os.Handler.dispatchMessage(Handler.java:95)
  at android.os.Looper.loop(Looper.java:171)
  at android.app.ActivityThread.main(ActivityThread.java:5720)
  at java.lang.reflect.Method.invoke!(Native method)
  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:732)
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:622)

可以看到，数据库 at android.database.sqlite.SQLiteConnectionPool.waitForConnection(SQLiteConnectionPool.java:670)
在主线程一直在等待链接。

总结

• 事务操作会影响对数据库操作，查询都要等待
• 不要在一大坨代码都放在事务操作里面。