????3. transient??????——??transient????????ε??????????????л???
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import java.io.Externalizable;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
/**
* @descripiton Externalizable???????
*
* @author Alexia
* @date 2013-10-15
*
*/
public class ExternalizableTest implements Externalizable {
private transient String content = "????????????л????????????transient?????????";
@Override
public void writeExternal(ObjectOutput out) throws IOException {
out.writeObject(content);
}
@Override
public void readExternal(ObjectInput in) throws IOException??
ClassNotFoundException {
content = (String) in.readObject();
}
public static void main(String[] args) throws Exception {
ExternalizableTest et = new ExternalizableTest();
ObjectOutput out = new ObjectOutputStream(new FileOutputStream(
new File("test")));
out.writeObject(et);
ObjectInput in = new ObjectInputStream(new FileInputStream(new File(
"test")));
et = (ExternalizableTest) in.readObject();
System.out.println(et.content);
out.close();
in.close();
}
}

????content?????????л????e???????????????????????н?????
????????????????л????????????transient?????????
???????????????????????????transient???????????????????л?????
?????????????Java?У?????????л???????????????????????????????Serializable?????????е????л???????????У?????????Externalizable??????????κζ?????????????л????????writeExternal?????н???????????????л???????????????transient?????????????????????????????content??????????????????null??