Android与Internet(获取资源，多线程断点上载，get/post发送，发送xml)

Android与Internet(获取资源，多线程断点下载，get/post发送，发送xml)

从Internet获取数据

利用HttpURLConnection对象,我们可以从网络中获取网页数据.

URL url = new URL("http://www.sohu.com");

HttpURLConnection conn = (HttpURLConnection) url.openConnection();

conn.setConnectTimeout(5* 1000);//设置连接超时

conn.setRequestMethod(“GET”);//以get方式发起请求

if (conn.getResponseCode() != 200) throw new RuntimeException("请求url失败");

InputStream is = conn.getInputStream();//得到网络返回的输入流

String result = readData(is, "GBK");

conn.disconnect();

//第一个参数为输入流,第二个参数为字符集编码

public static String readData(InputStream inSream, String charsetName) throws Exception{

ByteArrayOutputStream outStream = new ByteArrayOutputStream();

byte[] buffer = new byte[1024];

int len = -1;

while( (len = inSream.read(buffer)) != -1 ){

outStream.write(buffer, 0, len);

}

byte[] data = outStream.toByteArray();

outStream.close();

inSream.close();

return new String(data, charsetName);

}

<uses-permission android:name="android.permission.INTERNET"/>
利用HttpURLConnection对象,我们可以从网络中获取文件数据.URL url = new URL("http://photocdn.sohu.com/20100125/Img269812337.jpg");HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setConnectTimeout(5* 1000);conn.setRequestMethod("GET");if (conn.getResponseCode() != 200) throw new RuntimeException("请求url失败");InputStream is = conn.getInputStream();readAsFile(is, "Img269812337.jpg");?public static void readAsFile(InputStream inSream, File file) throws Exception{FileOutputStream outStream = new FileOutputStream(file);byte[] buffer = new byte[1024];int len = -1;while( (len = inSream.read(buffer)) != -1 ){outStream.write(buffer, 0, len);}? outStream.close();inSream.close();}
多线程下载
Android与Internet(获取资源，多线程断点上载，get/post发送，发送xml)

Android与Internet(获取资源，多线程断点上载，get/post发送，发送xml)

?使用多线程下载文件可以更快完成文件的下载，多线程下载文件之所以快，是因为其抢占的服务器资源多。如：假设服务器同时最多服务100个用户，在服务器中一条线程对应一个用户，100条线程在计算机中并非并发执行，而是由CPU划分时间片轮流执行，如果A应用使用了99条线程下载文件，那么相当于占用了99个用户的资源，假设一秒内CPU分配给每条线程的平均执行时间是10ms，A应用在服务器中一秒内就得到了990ms的执行时间，而其他应用在一秒内只有10ms的执行时间。就如同一个水龙头，每秒出水量相等的情况下，放990毫秒的水肯定比放10毫秒的水要多。多线程下载的实现过程：1>首先得到下载文件的长度，然后设置本地文件的长度。HttpURLConnection.getContentLength();RandomAccessFile file = new RandomAccessFile("QQWubiSetup.exe","rw");file.setLength(filesize);//设置本地文件的长度2>根据文件长度和线程数计算每条线程下载的数据长度和下载位置。如：文件的长度为6M，线程数为3，那么，每条线程下载的数据长度为2M，每条线程开始下载的位置如上图所示。3>使用Http的Range头字段指定每条线程从文件的什么位置开始下载，如：指定从文件的2M位置开始下载文件，代码如下：HttpURLConnection.setRequestProperty("Range", "bytes=2097152-");4>保存文件，使用RandomAccessFile类指定每条线程从本地文件的什么位置开始写入数据。RandomAccessFile threadfile = new RandomAccessFile("QQWubiSetup.exe ","rw");threadfile.seek(2097152);//从文件的什么位置开始写入数据
向Internet发送请求参数利用HttpURLConnection对象,我们可以向网络发送请求参数.String requestUrl = "http://localhost:8080/itcast/contanctmanage.do";Map<String, String> requestParams = new HashMap<String, String>();requestParams.put("age", "12");requestParams.put("name", "中国");?StringBuilder params = new StringBuilder();for(Map.Entry<String, String> entry : requestParams.entrySet()){params.append(entry.getKey());params.append("=");params.append(URLEncoder.encode(entry.getValue(), "UTF-8"));params.append("&");}if (params.length() > 0) params.deleteCharAt(params.length() - 1);byte[] data = params.toString().getBytes();URL realUrl = new URL(requestUrl);HttpURLConnection conn = (HttpURLConnection) realUrl.openConnection();conn.setDoOutput(true);//发送POST请求必须设置允许输出conn.setUseCaches(false);//不使用Cacheconn.setRequestMethod("POST"); ? ? ? ?conn.setRequestProperty("Connection", "Keep-Alive");//维持长连接conn.setRequestProperty("Charset", "UTF-8");conn.setRequestProperty("Content-Length", String.valueOf(data.length));conn.setRequestProperty("Content-Type","application/x-www-form-urlencoded");DataOutputStream outStream = new DataOutputStream(conn.getOutputStream());outStream.write(data);outStream.flush();if( conn.getResponseCode() == 200 ){?? ? ? ?String result = readAsString(conn.getInputStream(), "UTF-8");?? ? ? ?outStream.close();?? ? ? ?System.out.println(result);}向Internet发送xml数据利用HttpURLConnection对象,我们可以向网络发送请求参数.String requestUrl = "http://localhost:8080/itcast/contanctmanage.do";Map<String, String> requestParams = new HashMap<String, String>();requestParams.put("age", "12");requestParams.put("name", "中国");?StringBuilder params = new StringBuilder();for(Map.Entry<String, String> entry : requestParams.entrySet()){params.append(entry.getKey());params.append("=");params.append(URLEncoder.encode(entry.getValue(), "UTF-8"));params.append("&");}if (params.length() > 0) params.deleteCharAt(params.length() - 1);byte[] data = params.toString().getBytes();URL realUrl = new URL(requestUrl);HttpURLConnection conn = (HttpURLConnection) realUrl.openConnection();conn.setDoOutput(true);//发送POST请求必须设置允许输出conn.setUseCaches(false);//不使用Cacheconn.setRequestMethod("POST"); ? ? ? ?conn.setRequestProperty("Connection", "Keep-Alive");//维持长连接conn.setRequestProperty("Charset", "UTF-8");conn.setRequestProperty("Content-Length", String.valueOf(data.length));conn.setRequestProperty("Content-Type","application/x-www-form-urlencoded");DataOutputStream outStream = new DataOutputStream(conn.getOutputStream());outStream.write(data);outStream.flush();if( conn.getResponseCode() == 200 ){?? ? ? ?String result = readAsString(conn.getInputStream(), "UTF-8");?? ? ? ?outStream.close();?? ? ? ?System.out.println(result);}向Internet发送xml数据利用HttpURLConnection对象,我们可以向网络发送xml数据.StringBuilder xml = ?new StringBuilder();xml.append("<?xml version=\"1.0\" encoding=\"utf-8\" ?>");xml.append("<M1 V=10000>");xml.append("<U I=1 D=\"N73\">中国</U>");xml.append("</M1>");byte[] xmlbyte = xml.toString().getBytes("UTF-8");URL url = new URL("http://localhost:8080/itcast/contanctmanage.do?method=readxml");HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setConnectTimeout(5* 1000);conn.setDoOutput(true);//允许输出conn.setUseCaches(false);//不使用Cacheconn.setRequestMethod("POST"); ? ? ? ?conn.setRequestProperty("Connection", "Keep-Alive");//维持长连接conn.setRequestProperty("Charset", "UTF-8");conn.setRequestProperty("Content-Length", String.valueOf(xmlbyte.length));conn.setRequestProperty("Content-Type", "text/xml; charset=UTF-8");DataOutputStream outStream = new DataOutputStream(conn.getOutputStream());outStream.write(xmlbyte);//发送xml数据outStream.flush();if (conn.getResponseCode() != 200) throw new RuntimeException("请求url失败");InputStream is = conn.getInputStream();//获取返回数据String result = readAsString(is, "UTF-8");outStream.close();

Android与Internet(获取资源多线程断

热点推荐