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尽管目前的无线网络不够理想,手机联网还是给我们开发人员不小的震撼的。毕竟这真的是件神奇的事情,不是吗?本文将讲述如何应用J2ME平台中的通用联网框架开发联网的应用程序。
首先,必须说明一点:MIDP中规定,任何移动信息设备都必须提供通过http协议的支持,而像其他的通信方式例如socket是设备相关的。有些手机会支持,有些则不支持。这里只大概的说明一下http协议相关的内容,如果不了解这个方面的知识请参考http协议。在javax.microedition.io里面是大量的接口,只有一个connector类,当然在midp2.0里面添加了对push技术的支持,这个留做以后讲。connector类提供的最重要的方法是open()方法,它的返回值为Connection,你可以对他进行转换得到你需要的类型,比如我们以http协议访问服务器。 void postViaHttpConnection(String url) throws IOException { HttpConnection c = null; InputStream is = null; OutputStream os = null; int rc;
try { c = (HttpConnection)Connector.open(url);
// Set the request method and headers c.setRequestMethod(HttpConnection.POST); c.setRequestProperty("If-Modified-Since", "29 Oct 1999 19:43:31 GMT"); c.setRequestProperty("User-Agent", "Profile/MIDP-2.0 Configuration/CLDC-1.0"); c.setRequestProperty("Content-Language", "en-US");
// Getting the output stream may flush the headers os = c.openOutputStream(); os.write("LIST games\n".getBytes()); os.flush(); // Optional, getResponseCode will flush
// Getting the response code will open the connection, // send the request, and read the HTTP response headers. // The headers are stored until requested. rc = c.getResponseCode(); if (rc != HttpConnection.HTTP_OK) { throw new IOException("HTTP response code: " + rc); }
is = c.openInputStream();
// Get the ContentType String type = c.getType(); processType(type);
// Get the length and process the data int len = (int)c.getLength(); if (len > 0) { int actual = 0; int bytesread = 0 ; byte[] data = new byte[len]; while ((bytesread != len) && (actual != -1)) { actual = is.read(data, bytesread, len - bytesread); [1] [2] [3] [4] [5] [6] [7] 下一页
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