Android: 内存不足错误 StringBuilder

Question

在我的应用中，我以JSON格式从服务器获取数据，数据大小约为1.5 MB。应用程序可以运行，但有时在从服务器获取数据时会崩溃，并显示OutOfMemoryError错误。

这是我的方法：

private String sendPostRequest(String url, List<NameValuePair> params)
        throws Exception {
    String ret = null;

    BufferedReader bufferedReader = null;
    HttpClient httpClient = new DefaultHttpClient();
    HttpPost request = new HttpPost(url);

    try {
        UrlEncodedFormEntity entity = new UrlEncodedFormEntity(params);
        request.setEntity(entity);

        HttpResponse response = httpClient.execute(request);

        bufferedReader = new BufferedReader(new InputStreamReader(response
                .getEntity().getContent()));
        StringBuilder stringBuilder = new StringBuilder("");
        StringBuilder stringBuilder2;
        String line = "";
        //String LineSeparator = System.getProperty("line.separator");
        while ((line = bufferedReader.readLine()) != null) {
            stringBuilder.append(line);
        }
        bufferedReader.close();

        ret = stringBuilder.toString();
        stringBuilder = null;

    } catch (ClientProtocolException e) {
        e.printStackTrace();
        // TODO: report an error
    } catch (IOException e) {
        e.printStackTrace();
        // TODO: report an error
    } finally {
        if (bufferedReader != null) {
            try {
                bufferedReader.close();
            } catch (IOException e) {
                e.printStackTrace();
                // TODO Auto-generated catch block
            }
        }
    }
    return ret;
}

我尝试在使用后将StringBuilder设置为null，但没有起作用。 我在下面发布logcat跟踪：

10-23 03:39:25.271: E/dalvikvm-heap(1011): Out of memory on a 4116282-byte allocation.
10-23 03:39:25.271: I/dalvikvm(1011): "AsyncTask #1" prio=5 tid=11 RUNNABLE
10-23 03:39:25.271: I/dalvikvm(1011):   | group="main" sCount=0 dsCount=0 obj=0x417c5e88 self=0x2a1d1db8
10-23 03:39:25.271: I/dalvikvm(1011):   | sysTid=1025 nice=10 sched=0/0 cgrp=apps/bg_non_interactive handle=706552328
10-23 03:39:25.271: I/dalvikvm(1011):   | state=R schedstat=( 3053328788 23773807212 6541 ) utm=241 stm=64 core=0
10-23 03:39:25.271: I/dalvikvm(1011):   at java.lang.String.<init>(String.java:~422)
10-23 03:39:25.271: I/dalvikvm(1011):   at java.lang.AbstractStringBuilder.toString(AbstractStringBuilder.java:642)
10-23 03:39:25.282: I/dalvikvm(1011):   at java.lang.StringBuilder.toString(StringBuilder.java:663)
10-23 03:39:25.282: I/dalvikvm(1011):   at com.dzo.redacted.driverapp.datalayer.ServerConnect.sendPostRequest(ServerConnect.java:128)
10-23 03:39:25.282: I/dalvikvm(1011):   at com.dzo.redacted.driverapp.datalayer.ServerConnect.Sync(ServerConnect.java:61)
10-23 03:39:25.282: I/dalvikvm(1011):   at com.dzo.redacted.driverapp.datalayer.DBSync.Login(DBSync.java:59)
10-23 03:39:25.282: I/dalvikvm(1011):   at com.dzo.redacted.driverapp.asynctask.SyncDBTask.doInBackground(SyncDBTask.java:52)
10-23 03:39:25.282: I/dalvikvm(1011):   at com.dzo.redacted.driverapp.asynctask.SyncDBTask.doInBackground(SyncDBTask.java:1)
10-23 03:39:25.282: I/dalvikvm(1011):   at android.os.AsyncTask$2.call(AsyncTask.java:287)
10-23 03:39:25.282: I/dalvikvm(1011):   at java.util.concurrent.FutureTask.run(FutureTask.java:234)
10-23 03:39:25.282: I/dalvikvm(1011):   at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
10-23 03:39:25.282: I/dalvikvm(1011):   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
10-23 03:39:25.282: I/dalvikvm(1011):   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
10-23 03:39:25.282: I/dalvikvm(1011):   at java.lang.Thread.run(Thread.java:841)
10-23 03:39:25.282: W/dalvikvm(1011): threadid=11: thread exiting with uncaught exception (group=0x41465700)
10-23 03:39:25.292: I/Choreographer(1011): Skipped 30 frames!  The application may be doing too much work on its main thread.
10-23 03:39:25.491: E/AndroidRuntime(1011): FATAL EXCEPTION: AsyncTask #1
10-23 03:39:25.491: E/AndroidRuntime(1011): java.lang.RuntimeException: An error occured while executing doInBackground()
10-23 03:39:25.491: E/AndroidRuntime(1011):     at android.os.AsyncTask$3.done(AsyncTask.java:299) 
10-23 03:39:25.491: E/AndroidRuntime(1011):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at java.util.concurrent.FutureTask.run(FutureTask.java:239)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at java.lang.Thread.run(Thread.java:841)
10-23 03:39:25.491: E/AndroidRuntime(1011): Caused by: java.lang.OutOfMemoryError
10-23 03:39:25.491: E/AndroidRuntime(1011):     at java.lang.String.<init>(String.java:422)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at java.lang.AbstractStringBuilder.toString(AbstractStringBuilder.java:642)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at java.lang.StringBuilder.toString(StringBuilder.java:663)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at com.dzo.redacted.driverapp.datalayer.ServerConnect.sendPostRequest(ServerConnect.java:128)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at com.dzo.redacted.driverapp.datalayer.ServerConnect.Sync(ServerConnect.java:61)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at com.dzo.redacted.driverapp.datalayer.DBSync.Login(DBSync.java:59)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at com.dzo.redacted.driverapp.asynctask.SyncDBTask.doInBackground(SyncDBTask.java:52)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at com.dzo.redacted.driverapp.asynctask.SyncDBTask.doInBackground(SyncDBTask.java:1)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at android.os.AsyncTask$2.call(AsyncTask.java:287)
10-23 03:39:25.491: E/AndroidRuntime(1011):     at java.util.concurrent.FutureTask.run(FutureTask.java:234)
10-23 03:39:25.491: E/AndroidRuntime(1011):     ... 4 more
10-23 03:39:28.091: E/WindowManager(1011): Activity com.dzo.redacted.driverapp.LoginActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{4178fcb0 V.E..... R.....ID 0,0-479,96} that was originally added here
10-23 03:39:28.091: E/WindowManager(1011): android.view.WindowLeaked: Activity com.dzo.redacted.driverapp.LoginActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{4178fcb0 V.E..... R.....ID 0,0-479,96} that was originally added here
10-23 03:39:28.091: E/WindowManager(1011):  at android.view.ViewRootImpl.<init>(ViewRootImpl.java:345)
10-23 03:39:28.091: E/WindowManager(1011):  at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:239)
10-23 03:39:28.091: E/WindowManager(1011):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
10-23 03:39:28.091: E/WindowManager(1011):  at android.app.Dialog.show(Dialog.java:281)
10-23 03:39:28.091: E/WindowManager(1011):  at com.dzo.redacted.driverapp.asynctask.SyncDBTask.onPreExecute(SyncDBTask.java:43)
10-23 03:39:28.091: E/WindowManager(1011):  at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
10-23 03:39:28.091: E/WindowManager(1011):  at android.os.AsyncTask.execute(AsyncTask.java:534)
10-23 03:39:28.091: E/WindowManager(1011):  at com.dzo.redacted.driverapp.asynctask.LoginAsyncTask.onPostExecute(LoginAsyncTask.java:87)
10-23 03:39:28.091: E/WindowManager(1011):  at com.dzo.redacted.driverapp.asynctask.LoginAsyncTask.onPostExecute(LoginAsyncTask.java:1)
10-23 03:39:28.091: E/WindowManager(1011):  at android.os.AsyncTask.finish(AsyncTask.java:631)
10-23 03:39:28.091: E/WindowManager(1011):  at android.os.AsyncTask.access$600(AsyncTask.java:177)
10-23 03:39:28.091: E/WindowManager(1011):  at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
10-23 03:39:28.091: E/WindowManager(1011):  at android.os.Handler.dispatchMessage(Handler.java:99)
10-23 03:39:28.091: E/WindowManager(1011):  at android.os.Looper.loop(Looper.java:137)
10-23 03:39:28.091: E/WindowManager(1011):  at android.app.ActivityThread.main(ActivityThread.java:5103)
10-23 03:39:28.091: E/WindowManager(1011):  at java.lang.reflect.Method.invokeNative(Native Method)
10-23 03:39:28.091: E/WindowManager(1011):  at java.lang.reflect.Method.invoke(Method.java:525)
10-23 03:39:28.091: E/WindowManager(1011):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
10-23 03:39:28.091: E/WindowManager(1011):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
10-23 03:39:28.091: E/WindowManager(1011):  at dalvik.system.NativeStart.main(Native Method)
10-23 03:44:25.761: I/Process(1011): Sending signal. PID: 1011 SIG: 9

更新1

我再次尝试了这种方法，但在我的情况下仍然出现toString()错误，与toString()相关的问题也出现在我尝试Amit的回答时。是否与toString()有关。

更新2

将新的字符串构建器对象的创建从while循环中移除，并且现在不使用行分隔符。但是，这并没有产生太大的差异。应用程序第一次运行时正常，但如果我连续运行2-3次，则会再次出现相同的问题。

- Nitish

---

也许这个能解决你的问题。 - i5h4n

谢谢，但应用程序将在手机和平板电脑上运行，因此我无法增加手机的堆大小。 - Nitish

Answer 1

如果你没有足够的内存来存储字符串，你可以：释放一些内存、减少内存消耗并且不要把字符串存储在内存中。

在你的情况下，你需要：

- 存储响应所需的内存(大约1.5+mb) - 字符串构建器所需的内存 (大约1.5+mb) - 结果字符串所需的内存(连续的1.5+mb十分糟糕) - BufferedReader/InputStreamReader等所需的一些内存(kilo级别)

选项：

1. 将响应转换为字符串不使用字符串构建器。这样可以节省1+mb。
2. 将响应作为流读取并将其转换为字符串，而不使用字符串构建器请求/响应实体流。这样可以节省约3mb。
3. 不要将响应转换为字符串。将其作为流读取并保存到文件或数据库中，或者将流提供给流式JSON解析器。
4. 在发送您的POST请求之前尽可能释放内存，并开始祈祷一切都会顺利。

- Leonidos

---

谢谢指出这个错误。我选择了第三种解决方案。它运行良好。 - Nitish

先生，这是否意味着如果我直接将InputStream传递给Gson本身，那么我就不会遇到使用字符串构建器时发生的OOM异常？请协助。谢谢。 - Rat-a-tat-a-tat Ratatouille

我不明白一个拥有512MB RAM且有足够空闲内存的设备为什么会在分配区区6或8MB的字符串时出现问题。 - Michael

嗨Leonidos / Nitish，你能给我第三个选项的参考链接吗？ - Naveen Kumar M

Answer 2

只需在您的清单文件中的 <application /> 标记中添加此代码：

android:largeHeap="true"

- Ameen Maheen

---

这不是一个修复，它只是隐藏了问题。 - Omid Heshmatinia

Answer 3

试试这样写：

private String sendPostRequest(String url, List<NameValuePair> params)
        throws Exception {
    String ret = null;
    BufferedReader bufferedReader = null;
    HttpClient httpClient = new DefaultHttpClient();
    HttpPost request = new HttpPost(url);

    try {
        UrlEncodedFormEntity entity = new UrlEncodedFormEntity(params);
        request.setEntity(entity);

        HttpResponse response = httpClient.execute(request);
        bufferedReader = new BufferedReader(new InputStreamReader(response
                .getEntity().getContent()));
        String line = "";
        while ((line = bufferedReader.readLine()) != null) {
           ret =ret +line;
        }
        bufferedReader.close();

    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (bufferedReader != null) {
            try {
                bufferedReader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    return ret;
}

- Amit Gupta

---

仍然出现同样的原因导致内存溢出错误，没有解决…… - Nitish

你能否对以上方法中的错误进行指点？ - Nitish

@Nitish StringBuilder仍然存在，但被隐藏在字符串+运算符中。 - Michael