新的ObjectInputStream()块

Question

public class SerProg {


    static ServerSocket ser=null;
    static Socket cli=null;
    static ObjectInputStream ins=null;
    static ObjectOutputStream outs=null;


    public static void main(String[] args) {

        try {

            ser=new ServerSocket(9000,10);
            cli=ser.accept();

            System.out.println("Connected to :"+cli.getInetAddress().getHostAddress()+" At Port :"+cli.getLocalPort());

            ins=new ObjectInputStream(cli.getInputStream());
            outs=new ObjectOutputStream(cli.getOutputStream());

            String str=(String)ins.readObject();


        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


    }

}

和客户

public class SerProg {

    /**
     * @param args
     */
    static ServerSocket ser=null;
    static Socket cli=null;
    static ObjectInputStream ins=null;
    static ObjectOutputStream outs=null;


    public static void main(String[] args) {
        // TODO Auto-generated method stub

        try {

            ser=new ServerSocket(9000,10);
            cli=ser.accept();

            System.out.println("Connected to :"+cli.getInetAddress().getHostAddress()+" At Port :"+cli.getLocalPort());

            ins=new ObjectInputStream(cli.getInputStream());
            outs=new ObjectOutputStream(cli.getOutputStream());

            String str=(String)ins.readObject();


        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


    }

}

连接已成功建立,但在服务器代码行中

ins=new ObjectInputStream(cli.getInputStream());

代码停止并且不继续,可能是什么问题？

Answer 1

您需要在连接的两侧创建ObjectOutputStream之前ObjectInputStream(!).当ObjectInputStream被创建,它会尝试读取来自该对象流报头InputStream.因此,如果ObjectOutputStream尚未创建另一侧,则没有要读取的对象流标头,并且它将无限期地阻塞.

或者用不同的方式表达:如果双方首先构造ObjectInputStream,两者都会阻止尝试读取对象流标题,直到ObjectOutputStream创建之后才会写入(在行的另一侧); 这将永远不会发生,因为双方都被阻止在构造函数中ObjectInputStream.

这可以从Javadoc推断ObjectInputStream(InputStream in):

从流中读取序列化流头并进行验证.此构造函数将阻塞,直到相应的ObjectOutputStream已写入并刷新标头.

这也在Esmond Pitt的Java基础网络部分3.6.2中描述.