是不是可以附加到ObjectOutputStream？
我试图附加到对象列表.以下代码段是一个在作业完成时调用的函数.
FileOutputStream fos = new FileOutputStream
(preferences.getAppDataLocation() + "history" , true);
ObjectOutputStream out = new ObjectOutputStream(fos);
out.writeObject( new Stuff(stuff) );
out.close();
但是当我尝试阅读它时,我只得到文件中的第一个.然后我明白了java.io.StreamCorruptedException.
阅读我正在使用
FileInputStream fis = new FileInputStream
( preferences.getAppDataLocation() + "history");
ObjectInputStream in = new ObjectInputStream(fis);
try{
while(true)
history.add((Stuff) in.readObject());
}catch( Exception e ) {
System.out.println( e.toString() );
}
我不知道会有多少个物品存在,所以我在读书时没有例外.从谷歌所说的这是不可能的.我想知道是否有人知道方法？
java serialization append objectoutputstream objectinputstream
如何将java对象转换为InputStream？
我编写了以下代码,将4000字节的0写入文件test.txt.然后,我一次以1000字节的块读取相同的文件.
FileOutputStream output = new FileOutputStream("test.txt");
ObjectOutputStream stream = new ObjectOutputStream(output);
byte[] bytes = new byte[4000];
stream.write(bytes);
stream.close();
FileInputStream input = new FileInputStream("test.txt");
ObjectInputStream s = new ObjectInputStream(input);
byte[] buffer = new byte[1000];
int read = s.read(buffer);
while (read > 0) {
System.out.println("Read " + read);
read = s.read(buffer);
}
s.close();
我期望发生的是四次读取1000个字节.
Read 1000
Read 1000
Read 1000
Read 1000
然而,实际发生的事情是,我似乎每1024字节"暂停"(因为缺少一个更好的词).
Read 1000
Read 24
Read 1000
Read 24
Read 1000
Read 24
Read 928
如果我尝试读取超过1024个字节,那么我的上限为1024字节.如果我尝试读取少于1024个字节,我仍然需要暂停1024字节标记.
在输出文件的检查test.txt …
我有以下代码,显示我的错误或误解.
我发送了相同的列表,但修改了ObjectOutputStream.一次为[0],另一次为[1].但是当我读到它时,我得到[0]两次.我认为这是因为我发送的是同一个对象而ObjectOutputStream必须以某种方式缓存它们.
这是应该的工作,还是应该提交错误？
import java.io.*;
import java.net.*;
import java.util.*;
public class OOS {
public static void main(String[] args) throws Exception {
Thread t1 = new Thread(new Runnable() {
public void run() {
try {
ServerSocket ss = new ServerSocket(12344);
Socket s= ss.accept();
ObjectOutputStream oos = new ObjectOutputStream(s.getOutputStream());
List same = new ArrayList();
same.add(0);
oos.writeObject(same);
same.clear();
same.add(1);
oos.writeObject(same);
} catch(Exception e) {
e.printStackTrace();
}
}
});
t1.start();
Socket s = new Socket("localhost", 12344);
ObjectInputStream ois = new ObjectInputStream(s.getInputStream());
// outputs [0] … 我正在尝试使用Java中的套接字和对象流来进行本地IPC但是我看到性能不佳.
我正在测试通过ObjectOutputStream发送对象的ping时间,以通过Socket上的ObjectInputStream接收回复.
这是请求者:
public SocketTest(){
int iterations = 100;
try {
Socket socket = new Socket("localhost", 1212);
ObjectInputStream objectInputStream = new ObjectInputStream(socket.getInputStream());
ObjectOutputStream objectOutputStream = new ObjectOutputStream(socket.getOutputStream());
double start = System.currentTimeMillis();
for (int i = 0; i < iterations; ++i) {
Request request = new Request();
objectOutputStream.writeObject(request);
Response response = (Response)objectInputStream.readObject();
}
double finish = System.currentTimeMillis();
System.out.println("Per ping: " + (finish - start) / iterations );
} catch (Exception e) {
e.printStackTrace();
}
}
这是响应者:
public ServerSocketTest(){
try {
ServerSocket …java sockets performance objectoutputstream objectinputstream
所以基本上我正在写一个客户端 - 服务器多人游戏.我有一个SeverCommunicationThread,如果他收到RequestForGame就会创建一个gameThread来创建gameThread.当我发送一个RequestForGame异常时抛出java.io.StreamCorruptedException:无效的类型代码:00我假设它是因为两个线程都试图读取相同的ObjectInputStream,我对它是如何工作的我没有太多了解,我只知道如何使用它.你能帮我理解问题是什么以及如何解决？谢谢 :)
public class ServerCommunicationThread extends Thread{
private Socket connectionSocket;
private ObjectInputStream inFromClient;
private ObjectOutputStream outToClient;
private String nickname;
private ServerModelManager model;
public ServerCommunicationThread(Socket connectionSocket,
ServerModelManager model) throws IOException {
this.connectionSocket = connectionSocket;
inFromClient = new ObjectInputStream(connectionSocket.getInputStream());
outToClient = new ObjectOutputStream(connectionSocket.getOutputStream());
this.model = model;
start();
}
public void run() {
try {
String nickname = (String) inFromClient.readObject();
if (model.exists(nickname)){
System.out.println(nickname + " already exists");
outToClient.writeObject(new MessageForClient("Please choose another nickname"));
}
else
{
System.out.println(nickname + " connected, adding to …在Java中,我们使用序列化的writeObject(Object obj)方法.ObjectOutputStreamObject
但是因为该方法只接受实现java.io.Serializable接口的对象(或者它会抛出NotSerializableException),为什么它仍然使用Object参数而不是Serializable像writeObject(Serializable o)？
有任何设计考虑因素吗？
我想为我的项目维护一个Bank用户的数据库.我能够将用户数保存在一个可序列化文件中.但是当我尝试将用户保存到数据库时,它只将最新的一个添加到数据库中.
下面是写入对象的代码的潜行高峰:
if(e.getSource()==submit) {
if(uFName != null && uLName != null && uInitialDeposit !=0) {
if(uAccountType=="Savings") {
Random randomGenerator = new Random();
//Gets the number of users from file if file exists
File f = new File(fileNameAdmin);
if(f.exists() && !f.isDirectory()) {
admin=db.readFromAdminDatabase();
}
u[admin.numberOfUsers]= new User();
u[admin.numberOfUsers].fName=uFName;
u[admin.numberOfUsers].lName=uLName;
u[admin.numberOfUsers].initalDeposit=uInitialDeposit;
u[admin.numberOfUsers].interestRate=uInterestRate;
u[admin.numberOfUsers].accountType="Saving";
u[admin.numberOfUsers].accountNumber=690000+admin.numberOfSavingsAccount;
//Generates a 4 digit random number which will be used as ATM pin
u[admin.numberOfUsers].atmPin=randomGenerator.nextInt(9999-1000)+1000;
//A savings account will be created
sa[admin.numberOfSavingsAccount]=new SavingsAccount(u[admin.numberOfUsers].accountNumber,u[admin.numberOfUsers].fName,u[admin.numberOfUsers].lName,
u[admin.numberOfUsers].initalDeposit,
u[admin.numberOfUsers].interestRate);
u[admin.numberOfUsers].sa=sa[admin.numberOfSavingsAccount];
System.out.println(u[admin.numberOfUsers].sa.balance);
JOptionPane.showMessageDialog(submit,"Congratulations! You …java serialization objectoutputstream objectinputstream deserialization
我正在尝试序列化JSONObjects的ArrayList.但我得到错误:
05-07 01:04:24.130: WARN/System.err(913): java.io.NotSerializableException: org.json.JSONObject
05-07 01:04:24.130: WARN/System.err(913): at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1535)
05-07 01:04:24.130: WARN/System.err(913): at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1847)
05-07 01:04:24.130: WARN/System.err(913): at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1689)
05-07 01:04:24.130: WARN/System.err(913): at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1653)
05-07 01:04:24.130: WARN/System.err(913): at java.util.ArrayList.writeObject(ArrayList.java:651)
05-07 01:04:24.130: WARN/System.err(913): at java.lang.reflect.Method.invokeNative(Native Method)
05-07 01:04:24.130: WARN/System.err(913): at java.lang.reflect.Method.invoke(Method.java:507)
05-07 01:04:24.130: WARN/System.err(913): at java.io.ObjectOutputStream.writeHierarchy(ObjectOutputStream.java:1219)
05-07 01:04:24.130: WARN/System.err(913): at java.io.ObjectOutputStream.writeNewObject(ObjectOutputStream.java:1575)
05-07 01:04:24.130: WARN/System.err(913): at java.io.ObjectOutputStream.writeObjectInternal(ObjectOutputStream.java:1847)
05-07 01:04:24.130: WARN/System.err(913): at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1689)
05-07 01:04:24.130: WARN/System.err(913): at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:1653)
05-07 01:04:24.130: WARN/System.err(913): at org.stocktwits.activity.AddStocksActivity.serializeQuotes(AddStocksActivity.java:183)
05-07 01:04:24.130: WARN/System.err(913): at org.stocktwits.activity.AddStocksActivity.access$9(AddStocksActivity.java:178)
05-07 01:04:24.130: WARN/System.err(913): …我想创建ObjectOutputStream,但我不想将对象保存在文件中,那么如何做到这一点？所有教程(我发现)只说文件方式:
FileOutputStream fos = new FileOutputStream("t.tmp");
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(new Date());
oos.close();
我想将对象存储到数据库中,因此我需要在setBinaryStream()类中指定方法中的流PreparedStatement.
谢谢回答...