Intent传大数据的深入分析

        使用Intent传递数据大家都知道，但是如果你使用Intent传递大于1Mb的数据时，就一定会报如下的错误

2022-06-25 11:37:16.601 5901-5901/com.openld.senior E/JavaBinder: !!! FAILED BINDER TRANSACTION !!!  (parcel size = 1049112)
2022-06-25 11:37:16.602 5901-5901/com.openld.senior E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.openld.senior, PID: 5901
    java.lang.RuntimeException: Failure from system
        at android.app.Instrumentation.execStartActivity(Instrumentation.java:1711)
        at android.app.Activity.startActivityForResult(Activity.java:5192)
        at androidx.activity.ComponentActivity.startActivityForResult(ComponentActivity.java:574)
        at android.app.Activity.startActivityForResult(Activity.java:5150)
        at androidx.activity.ComponentActivity.startActivityForResult(ComponentActivity.java:560)
        at android.app.Activity.startActivity(Activity.java:5521)
        at android.app.Activity.startActivity(Activity.java:5489)
        at com.openld.seniorstructure.main.testintentbigdata.TestIntentTransBIgDataActivity.addListeners$lambda-0(TestIntentTransBIgDataActivity.kt:39)
        at com.openld.seniorstructure.main.testintentbigdata.TestIntentTransBIgDataActivity.$r8$lambda$57fJAR8O7Q8Thsg13Hl8D6OIbjo(Unknown Source:0)
        at com.openld.seniorstructure.main.testintentbigdata.TestIntentTransBIgDataActivity$$ExternalSyntheticLambda0.onClick(Unknown Source:2)
        at android.view.View.performClick(View.java:7125)
        at android.view.View.performClickInternal(View.java:7102)
        at android.view.View.access$3500(View.java:801)
        at android.view.View$PerformClick.run(View.java:27336)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
     Caused by: android.os.TransactionTooLargeException: data parcel size 1049112 bytes
        at android.os.BinderProxy.transactNative(Native Method)
        at android.os.BinderProxy.transact(BinderProxy.java:510)
        at android.app.IActivityTaskManager$Stub$Proxy.startActivity(IActivityTaskManager.java:3847)
        at android.app.Instrumentation.execStartActivity(Instrumentation.java:1705)
        at android.app.Activity.startActivityForResult(Activity.java:5192) 
        at androidx.activity.ComponentActivity.startActivityForResult(ComponentActivity.java:574) 
        at android.app.Activity.startActivityForResult(Activity.java:5150) 
        at androidx.activity.ComponentActivity.startActivityForResult(ComponentActivity.java:560) 
        at android.app.Activity.startActivity(Activity.java:5521) 
        at android.app.Activity.startActivity(Activity.java:5489) 
        at com.openld.seniorstructure.main.testintentbigdata.TestIntentTransBIgDataActivity.addListeners$lambda-0(TestIntentTransBIgDataActivity.kt:39) 
        at com.openld.seniorstructure.main.testintentbigdata.TestIntentTransBIgDataActivity.$r8$lambda$57fJAR8O7Q8Thsg13Hl8D6OIbjo(Unknown Source:0) 
        at com.openld.seniorstructure.main.testintentbigdata.TestIntentTransBIgDataActivity$$ExternalSyntheticLambda0.onClick(Unknown Source:2) 
        at android.view.View.performClick(View.java:7125) 
        at android.view.View.performClickInternal(View.java:7102) 
        at android.view.View.access$3500(View.java:801) 
        at android.view.View$PerformClick.run(View.java:27336) 
        at android.os.Handler.handleCallback(Handler.java:883) 
        at android.os.Handler.dispatchMessage(Handler.java:100) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:7356) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) 
2022-06-25 11:38:39.289 6145-6145/? E/m.openld.senio: Unknown bits set in runtime_flags: 0x8000

        看最关键的点其实很清楚

Caused by: android.os.TransactionTooLargeException: data parcel size 1049112 bytes

        就是说你的传输数据太大了，当前的大小达到了1049112 bytes。

        那我们进到TransactionTooLargeException的定义中去看看

/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
package android.os;
import android.os.RemoteException;
 
/**
 * The Binder transaction failed because it was too large.
 * <p>
 * During a remote procedure call, the arguments and the return value of the call
 * are transferred as {@link Parcel} objects stored in the Binder transaction buffer.
 * If the arguments or the return value are too large to fit in the transaction buffer,
 * then the call will fail.  {@link TransactionTooLargeException} is thrown as a
 * heuristic when a transaction is large, and it fails, since these are the transactions
 * which are most likely to overfill the transaction buffer.
 * </p><p>
 * The Binder transaction buffer has a limited fixed size, currently 1MB, which
 * is shared by all transactions in progress for the process.  Consequently this
 * exception can be thrown when there are many transactions in progress even when
 * most of the individual transactions are of moderate size.
 * </p><p>
 * There are two possible outcomes when a remote procedure call throws
 * {@link TransactionTooLargeException}.  Either the client was unable to send
 * its request to the service (most likely if the arguments were too large to fit in
 * the transaction buffer), or the service was unable to send its response back
 * to the client (most likely if the return value was too large to fit
 * in the transaction buffer).  It is not possible to tell which of these outcomes
 * actually occurred.  The client should assume that a partial failure occurred.
 * </p><p>
 * The key to avoiding {@link TransactionTooLargeException} is to keep all
 * transactions relatively small.  Try to minimize the amount of memory needed to create
 * a {@link Parcel} for the arguments and the return value of the remote procedure call.
 * Avoid transferring huge arrays of strings or large bitmaps.
 * If possible, try to break up big requests into smaller pieces.
 * </p><p>
 * If you are implementing a service, it may help to impose size or complexity
 * contraints on the queries that clients can perform.  For example, if the result set
 * could become large, then don't allow the client to request more than a few records
 * at a time.  Alternately, instead of returning all of the available data all at once,
 * return the essential information first and make the client ask for additional information
 * later as needed.
 * </p>
 */
public class TransactionTooLargeException extends RemoteException {
    public TransactionTooLargeException() {
        super();
    }
 
    public TransactionTooLargeException(String msg) {
        super(msg);
    }
}

        英语好的话看下注释就明白了了，就是Binder数据传输的时候数据太大了。

        大意是说Binder传输依赖的是Bimder传输缓存，该缓存有1Mb的大小限制。而且该1Mb的缓存限制是被应用进程中的所有传输过程所共用的（言下之意是说你单个一次传输限制小于1Mb未必就不会出现上述的崩溃，别的传输过程也要占用部分空间的）。

        因此不崩溃的度在哪里？

        其实这里给的结论就是说你传输的时候尽量保证数据很小，当然正常情况下你用Intent传递数据的时候就是一些常用数据类型的key-value，本来就没多大，也不用担心触发该崩溃。

        但是，当你在页面间利用Intent传输图片的时候呢？是不是就很容易因为传输了较大格式的图片而导致该崩溃呢。此外延伸一下，假如onSaveInstanceState()方法和onRestoreInstanceState()方法触发的时候里面也要有Bundle的，那些存储在其中的数据也是受到1Mb的限制的。

        下面就给出解决办法，使用putBinder()方法传递大数据，此时使用的是共享内存而不是Binder传输缓存，因此不受1Mb的限制，但是使用该方法也有要注意的点。

        看下注释。

 
    /**
     * Inserts an {@link IBinder} value into the mapping of this Bundle, replacing
     * any existing value for the given key.  Either key or value may be null.
     *
     * <p class="note">You should be very careful when using this function.  In many
     * places where Bundles are used (such as inside of Intent objects), the Bundle
     * can live longer inside of another process than the process that had originally
     * created it.  In that case, the IBinder you supply here will become invalid
     * when your process goes away, and no longer usable, even if a new process is
     * created for you later on.</p>
     *
     * @param key a String, or null
     * @param value an IBinder object, or null
     */
    public void putBinder(@Nullable String key, @Nullable IBinder value) {
        unparcel();
        mMap.put(key, value);
    }

        意思是说一般情况在进程中利用Bundle传递数据时，Bundle在使用该数据的进程中存活的时间比创建该Bundle的进程中存活的时间要久。但是如果使用putBinder()方式传递数据时，数据在自定义的Binder中，创建Binder的进程一旦不存在，那Binder在使用它的进程中就会变为不可用。这一点在数据流转与取数据的时候一定要小心。

        下面直接给出我测试的核心代码，通过对比第一个点击事件一定会崩，第二个点击事件跳到了结果页且结果页正确地拿到了大数据。

触发页面代码如下：

package com.openld.seniorstructure.main.testintentbigdata
 
import android.content.Intent
import android.os.Binder
import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.appcompat.widget.AppCompatButton
import com.openld.seniorstructure.R
 
class TestIntentTransBIgDataActivity : AppCompatActivity() {
    private lateinit var mBtnFail: AppCompatButton
 
    private lateinit var mBtnSuccess: AppCompatButton
 
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_test_intent_trans_big_data)
 
        initWidgets()
 
        addListeners()
    }
 
    private fun initWidgets() {
        mBtnFail = findViewById(R.id.btn_fail)
        mBtnSuccess = findViewById(R.id.btn_success)
    }
 
    private fun addListeners() {
        // 必崩溃
        mBtnFail.setOnClickListener {
            val intent = Intent(
                this,
                TestIntentTransBigDataResultActivity::class.java
            )
            val data = ByteArray(1024 * 1024)
            val bundle = Bundle()
            bundle.putByteArray("bigData", data)
            intent.putExtra("bundle", bundle)
            startActivity(intent)
        }
 
        // 可以传递大数据
        mBtnSuccess.setOnClickListener {
            val intent = Intent(
                this,
                TestIntentTransBigDataResultActivity::class.java
            )
            val data = ByteArray(1024 * 1024)
            val bundle = Bundle()
            val bigData = BigData(ByteArray(1024 * 1024))
            bundle.putBinder("bigData", bigData)
            intent.putExtra("bundle", bundle)
            startActivity(intent)
        }
    }
}
 
data class BigData(val byteArray: ByteArray) : Binder() {
 
}

对应布局xml：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".main.testintentbigdata.TestIntentTransBIgDataActivity">
 
    <androidx.appcompat.widget.AppCompatButton
        android:id="@+id/btn_fail"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:background="@color/red"
        android:text="使用常规方式传递大数据"
        android:textAllCaps="false"
        android:textColor="@color/white"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:ignore="HardcodedText" />
 
    <androidx.appcompat.widget.AppCompatButton
        android:id="@+id/btn_success"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:background="@color/red"
        android:text="使用Binder方式传递大数据"
        android:textAllCaps="false"
        android:textColor="@color/white"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btn_fail"
        tools:ignore="HardcodedText" />
 
</androidx.constraintlayout.widget.ConstraintLayout>

结果页代码如下：

package com.openld.seniorstructure.main.testintentbigdata
 
import android.os.Bundle
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.openld.seniorstructure.R
 
class TestIntentTransBigDataResultActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_test_intent_trans_big_data_result)
 
        val bundle = intent.getBundleExtra("bundle")
        val ba = bundle?.getBinder("bigData") as BigData
        Toast.makeText(this, "" + ba.byteArray.size / 1024, Toast.LENGTH_SHORT).show()
    }
}

页面布局xml：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".main.testintentbigdata.TestIntentTransBigDataResultActivity">
 
    <androidx.appcompat.widget.AppCompatTextView
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_margin="16dp"
        android:autoSizeMaxTextSize="48sp"
        android:autoSizeMinTextSize="28sp"
        android:autoSizeTextType="uniform"
        android:gravity="center"
        android:lines="1"
        android:text="Intent传递大数据成功了呀"
        android:textColor="@color/red"
        android:textSize="36sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:ignore="HardcodedText"
        tools:targetApi="o" />
 
</androidx.constraintlayout.widget.ConstraintLayout>

最终大数据传递成功的结果截图

接到了1048576 Byte的数据