在这里，我将发布一个完美的例子，通过套接字发送和接收图像，音乐，视频或任何东西，以便谁可以使用它。它几近完美。它完成了这项工作，无论你在目标中拥有多少文件，它们都会计算它们并将它们发送到java服务器，但是我在服务器端收到一个例外：
Exception in thread "main" java.lang.IllegalArgumentException: Illegal Capacity: -1
at java.util.ArrayList.<init>(Unknown Source)
我真的不知道那是什么，但我很感激，如果你帮忙的话，我会为自己和任何一个发现自己需要一个人的人来说这个。感谢
Android Cliend：
package com.example.imagesender;
//File imagefile = new File(filepath);
// FileInputStream fis = null;
// try {
// fis = new FileInputStream(imagefile);
// } catch (FileNotFoundException e) {
// System.out.println("file not found");
// e.printStackTrace();
// }
// Bitmap bm = BitmapFactory.decodeStream(fis);
// imgbyte = new byte [(int)filepath.length()];
// imv.setImageBitmap(bm);
// Log.d("ClientActivity","length:"+imgbyte);
public class AccountCreator extends Activity {
private Button send;
private Socket socket;
private File f,fdst;
private FileInputStream fin,fises;
private static Context context;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.mes_registerpage);
send=(Button)findViewById(R.id.sendpic);
// sendWan=(Button)findViewById(R.id.sendWan);
AccountCreator.context = getApplicationContext();
send.setOnClickListener(new OnClickListener(){
public void onClick(View view){
this.doit();
}
class myAsync extends AsyncTask<String, Boolean, Boolean>{
@Override
protected Boolean doInBackground(String...urls){
try {
socket = new Socket("10.0.2.2", 1500);
System.out.println(socket);
System.out.println("Connecting...");
File fil=new
File(Environment.getExternalStorageDirectory()+"/Pictures/");
System.out.println(fil);
File[] Files=fil.listFiles();
System.out.println(Files);
for (int count=0;count < Files.length;count ++){
System.out.println(Files[count].getName());
}
OutputStream os = socket.getOutputStream();
DataOutputStream dos = new DataOutputStream(os);
dos.writeInt(Files.length);
for (int count=0;count<Files.length;count ++){
dos.writeUTF(Files[count].getName());
}
for (int count=0;count<Files.length;count ++){
int filesize = (int) Files[count].length();
dos.writeInt(filesize);
}
for (int count=0;count<Files.length;count ++){
int filesize = (int) Files[count].length();
byte [] buffer = new byte [filesize];
FileInputStream fis = new
FileInputStream(Files[count].toString());
BufferedInputStream bis = new BufferedInputStream(fis);
//Sending file name and file size to the server
bis.read(buffer, 0, buffer.length); //This line is important
dos.write(buffer, 0, buffer.length);
dos.flush();
//close socket connection
//socket.close();
}
// Toast.makeText(getApplicationContext(),"Transfer file
is completed!!", Toast.LENGTH_LONG).show();
socket.close();
}
catch(Exception e){
System.out.println("Error::"+e);
//System.out.println(e.getMessage());
//e.printStackTrace();
//Log.i("******* :( ", "UnknownHostException");
}
return null;
}
}
protected void onPostExecute(String result){
}
public void doit(){
myAsync sync = new myAsync();
sync.execute();
}
});}
}
和服务器端：
public class Server {
/**
* @param args
*/
public static void main(String[] args) throws IOException,EOFException {
// TODO Auto-generated method stub
FileOutputStream fos;
BufferedOutputStream bos;
OutputStream output;
DataOutputStream dos;
int len;
int smblen;
InputStream in;
DataInputStream clientData;
BufferedInputStream clientBuff;
ServerSocket serverSocket = new ServerSocket(1500);
Socket clientSocket = null;
clientSocket = serverSocket.accept();
in = clientSocket.getInputStream(); //used
clientData = new DataInputStream(in); //use
clientBuff = new BufferedInputStream(in); //use
int N=1;
while(N==1){
System.out.println("Starting...");
int fileSize = clientData.read();
fileSize = (fileSize > 0) ? fileSize:0;
List<File> files = new ArrayList<>(fileSize);
List<Integer> sizes = new ArrayList<>(fileSize);
for (int count=0;count < fileSize;count ++){
sizes.add(clientData.readInt());
}
for (int count =0;count < fileSize ;count ++){
len=sizes.get(count);
System.out.println("File Size ="+len);
//output = new FileOutputStream("C:/share/" + fileName);
output = new FileOutputStream("D://Users/" + files.get(count));
dos=new DataOutputStream(output);
bos=new BufferedOutputStream(output);
byte[] buffer = new byte[1024];
bos.write(buffer, 0, buffer.length); //This line is important
while (len > 0 && (smblen = clientData.read(buffer)) > 0) {
dos.write(buffer, 0, smblen);
len = len - smblen;
dos.flush();
}
N=2;
}
}
} //end loop
}
提前致谢
stacktrace：
Exception in thread "main" java.lang.IllegalArgumentException: Illegal Capacity: -1
at java.util.ArrayList.<init>(Unknown Source)
at Server.main(Server.java:49)
答案 0 :(得分：1)
不要将负值传递给ArrayList构造函数。您也可以使用菱形运算符（在Java 7+中），您可能更喜欢使用List接口。所以，像这样 -
int fileSize = clientData.read();
fileSize = (fileSize > 0) ? fileSize : 0; // guard against negatives.
List<File> files = new ArrayList<>(fileSize); // Using List and <>
List<Integer> sizes = new ArrayList<>(fileSize);
答案 1 :(得分：0)
你的问题在于以下几点：
int fileSize = clientData.read();
ArrayList<File>files=new ArrayList<File>(fileSize); //store list of filename from client directory
ArrayList<Integer>sizes = new ArrayList<Integer>(fileSize); //store file size from client
read方法在流结束时返回-1。您没有检查这个并尝试将其用作ArrayList的初始容量。添加适当的错误检查 - 你会没事的。