-1

读取 ObjectInputStream 时似乎出现了损坏。附加的代码段在完成之前引发异常。我将示例修复为按照建议调用 oos.writeObject( p1 )。

异常堆栈如下：

java.lang.OutOfMemoryError: Java heap space
at test.POJO.readExternal(STest.java:82)
at java.io.ObjectInputStream.readExternalData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at test.STest.test(STest.java:37)

我相信这个 OutOfMemoryError 异常具有误导性。我添加了一个显示 readExternal(..) 行为的打印语句，并且看到从 ObjectInputStream 中提取了一个很大的值，这与写入的内容无关。如果 DIM 设置为 5，如果设置为 15，它会起作用，我得到上述异常。如果我降低每个数组元素写入的字节数，我会获得更成功的迭代。

package test;

import static org.junit.Assert.*;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;

import org.junit.Test;

public class STest
{
    @Test
    public void test() throws Exception
    {
        POJO p1 = new POJO();
        POJO p2 = new POJO();

        // Initialize and serialize POJO 1
        // --------------------------------
        p1.hydrate();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream( baos );
        oos.writeObject( p1 );
        oos.flush();
        oos.close();
        byte [] baSerialized = baos.toByteArray();

        // Parse POJO 2
        // -------------
        ObjectInputStream ois = new ObjectInputStream( new ByteArrayInputStream( baSerialized ) );
        p2 = (POJO)ois.readObject();

        // Test Result
        // ------------
        byte [][] baa1 = p1._baa;
        byte [][] baa2 = p2._baa;
        for ( int i=0; i < baa1.length; i++ )
        {
            String str1 = new String( baa1[ i ] );
            String str2 = new String( baa2[ i ] );
            assertTrue( str1.equals( str2 ) );
        }
    }
}

class POJO implements Externalizable
{
    protected static final int DIM = 5; 
    protected byte [][] _baa = null;

    public POJO()
    {
    }

    public void hydrate()
    {
        _baa = new byte[ DIM ][];
        for ( int i = 0; i < _baa.length; i++ )
        {
            _baa[ i ] = ("This is a serialize and parse test, it will be interesting to see if it completes without exception, I suspect not as there appears be a bug in the JRE - " + i).getBytes();
        }
    }

    @Override
    public void readExternal( ObjectInput oi ) throws IOException, ClassNotFoundException
    {
        int iDim = oi.readInt();
        _baa = new byte[ iDim ][];      
        for ( int i=0; i < iDim; i++ )
        {
            int iSize = oi.readInt();

            System.out.println( iSize );

            byte [] ba = new byte[ iSize ];
            oi.read( ba );
            _baa[ i ] = ba;
        }
    }

    @Override
    public void writeExternal(  ObjectOutput oo ) throws IOException
    {
        oo.writeInt( _baa.length );
        for ( int i=0; i < _baa.length; i++ )
        {
            oo.writeInt( _baa[ i ].length );
            oo.write( _baa[ i ] );
        }
    }
}
4

1 回答 1

1 
p1.writeExternal(o);

那应该是：

oo.writeObject(p1);

您不应该直接调用自己的 writeExternal() 方法。ObjectOutputStream 就是这样做的。

于 2013-10-11T22:53:45.343 回答