您遇到了序列化问题.序列化是将某些数据转换为可以传输的格式的地方.有几种方法可以做到这一点,其他答案中提到了一些方法.

我建议使用JSON作为您的格式.你可以从json.org获得一个很好的Java JSON库.然后你可以简单地用库创建一个JSON数组并将其写入servlet的OutputStream.

public void service(ServletRequest req, ServletResponse res) {

final JSONArray arr=new JSONArray();

for (String s : this.myListOfStrings){

arr.put(s);

}

//Here we serialize the stream to a String.

final String output = arr.toString();

res.setContentLength(output.length());

//And write the string to output.

res.getOutputStream().write(output.getBytes());

res.getOutputStream().flush();

res.getOutputStream().close();

}

现在,从您的客户端,您可以发出请求并返回您的ArrayList,如下所示：

public ArrayList contactServer(){

final URL url = new URL(serverURL);

final URLConnection connection=url.openConnection();

connection.setDoOutput(true);

/*

* ...

* write your POST data to the connection.

* ...

*/

final BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));

final char[] buffer=new char[Integer.parseInt(connection.getHeaderField("Content-Length"))];

int bytesRead=0;

while (bytesRead < buffer.length){

bytesRead += br.read(buffer, bytesRead, buffer.length - bytesRead + 1);

}

final JSONArray arr = new JSONArray(new String(buffer));

final ArrayList ret = new ArrayList(arr.length());

for (int i=0; i

ret.add(arr.get(i));

}

return ret;

}