Android 巧用putBinder方法传递大文件

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：

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。

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。

 
    /**
     * 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。

发送方：

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() {
 
}

接收方：

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()
    }
}