通过Http协议获取网络资源,HttpURLConnection,HttpClient
使用java自带的包获取网络资源
public class TestHttpUrlConnection { public static void main(String[] args) { BufferedInputStream bis = null; BufferedOutputStream boStream = null; try { // 1,创建URL对象 统一资源定位符 跟互联网的一个路径相关联 URL url = new URL( "http://www.xiufa.com/BJUI/plugins/kindeditor_4.1.10/attached/image/20160427/20160427020327_69298.png"); // 2,创建HttpURLConnection对象 发起TCP连接 HttpURLConnection hc = (HttpURLConnection) url.openConnection(); // 3,设置请求参数 hc.setDoInput(true);// 默认true，允许从互联网读入数据 hc.setDoOutput(true);// 默认为false，允许向互联网写入数据 hc.setRequestMethod("GET");// 默认为GET 单词一定要大写 hc.setConnectTimeout(5000);// 设置连接超时时间 hc.setReadTimeout(5000);// 设置读取数据的超时时间 // 4,得到响应码 //404 找不到网页 500 服务端内部错误 400 ：服务端没有开启服务等 // 200 代表成功 int code = hc.getResponseCode(); if (code == 200) { // 5,得到对应的输入流 bis = new BufferedInputStream(hc.getInputStream()); System.out.println("文件总的大小：" + hc.getContentLength()); boStream = new BufferedOutputStream(new FileOutputStream("girl.png")); byte b[] = new byte[1024 * 1024];// 缓冲区 int len = 0;// 每次实际读取的字节数 while ((len = bis.read(b)) != -1) { boStream.write(b, 0, len); } System.out.println("下载完毕！"); } else { System.out.println("请求失败"); } } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { if (bis != null) { try { bis.close(); } catch (IOException e) { e.printStackTrace(); } } if (boStream != null) { try { boStream.close(); } catch (IOException e) { e.printStackTrace(); } } } } }
1 import java.io.IOException; 2 3 import org.apache.http.HttpEntity; 4 import org.apache.http.HttpResponse; 5 import org.apache.http.client.ClientProtocolException; 6 import org.apache.http.client.HttpClient; 7 import org.apache.http.client.methods.HttpGet; 8 import org.apache.http.client.methods.HttpPost; 9 import org.apache.http.impl.client.HttpClients; 10 import org.apache.http.util.EntityUtils; 11 12 /** 13 * HttpClient需要org.apache.http的包 14 * 比java自带的包URL更方便获取网络资源 15 * Get和Post 16 * @author Administrator 17 * 18 */ 19 public class TestHttpClient { 20 public static void main(String[] args) { 21 new Get().start(); 22 } 23 } 24 class Get extends Thread{ 25 @Override 26 public void run() { 27 HttpClient client=HttpClients.createDefault();//创造一个客服 28 HttpGet get=new HttpGet("http://www.baidu.com");//http地址 29 try { 30 HttpResponse response = client.execute(get);//客户执行http的请求得到回应 31 HttpEntity entity = response.getEntity();//获取 回应的实体 32 String result=EntityUtils.toString(entity, "utf-8");//通过实体的工具获取实体 33 System.out.println(result);//输出实体(就是读取的数据,通过浏览器就可以打开) 34 } catch (Exception e) { 35 e.printStackTrace(); 36 } 37 } 38 } 39 class Post extends Thread{ 40 @Override 41 public void run() { 42 HttpClient client=HttpClients.createDefault(); 43 HttpPost post=new HttpPost("https://www.baidu.com/s?tn=87048150_5_pg&cid=qb7.zhuye&ie=utf8&wd=%E5%9B%BE%E7%89%87&hdq=sogou-wsse-2f4ccb0f7a84f335"); 44 try { 45 HttpResponse execute = client.execute(post); 46 HttpEntity entity = execute.getEntity(); 47 String string = EntityUtils.toString(entity, "utf-8"); 48 System.out.println(string); 49 } catch (Exception e) { 50 e.printStackTrace(); 51 } 52 } 53 }
HttpURLConnection使用的步骤：
GET 表示希望从服务器那里获取数据，而 POST 则
表示希望提交数据给服务器。写法如下：
connection.setRequestMethod("GET");
接下来就可以进行一些自由的定制了，比如设置连接超时、读取超时的毫秒数，以及服
务器希望得到的一些消息头等。这部分内容根据自己的实际情况进行编写，示例写法如下：
connection.setConnectTimeout(8000);//当连接网络超过8秒就抛出异常
connection.setReadTimeout(8000);//从网络上读取数据超过8秒就抛出异常
之后再调用 getInputStream()方法就可以获取到服务器返回的输入流了，剩下的任务就是
对输入流进行读取
最后可以调用 disconnect()方法将这个 HTTP 连接关闭掉，如下所示：
connection.disconnect();
比如说我们想要向服务器提交用户名和密码，就可以这样写：
connection.setRequestMethod("POST");
DataOutputStream out = new DataOutputStream(connection.getOutputStream());
out.writeBytes("username=admin&password=123456");
总结：
两种方式：
HttpURLConnection方式：
HttpClient方式：
HttpClient的例子：get方式：
public class Test { public static void main(String[] args) { BufferedInputStream bis = null; BufferedOutputStream bos = null; try { // 1,创建HttpClient对象 HttpClient httpClient = new DefaultHttpClient(); // 2,创建请求对象 GET POST 注意指定地址 HttpGet get = new HttpGet( "http://dh2.kimg.cn/static/images/public/20160330/de12e1bb425286873d1237650c6312aa.jpg"); // 3,执行请求 HttpClient+HttpXXX = HttpResponse HttpResponse response = httpClient.execute(get); // 4,得到响应码 int code = response.getStatusLine().getStatusCode(); if (code == 200) { // 5,得到响应的HttpEntity对象 // HttpEntity是客户端服务端传递的载体 HttpEntity entity = response.getEntity(); bos = new BufferedOutputStream(new FileOutputStream("meinv1.jpg")); // 方法一 // // 6,从HttpENtity中得到输入流InoutStream is= entity.getContent(); // bis = new BufferedInputStream(entity.getContent()); // byte b[] = new byte[1024 * 1024]; // int len = 0; // while ((len = bis.read(b)) != -1) { // bos.write(b, 0, len); // bos.flush(); // } // 方法二 // 图片 音频 byte b[] = EntityUtils.toByteArray(entity); bos.write(b); // 文本 json xml 普通的文本 // String string = EntityUtils.toString(entity); System.out.println("ok"); } else { System.out.println("请求失败"); } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { if (bis != null) { try { bis.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if (bos != null) { try { bos.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } }
post方式：
public class TestPost { public static void main(String[] args) { BufferedReader bReader = null; try { // 1,创建HttpClient对象 HttpClient httpClient = new DefaultHttpClient(); // 2,创建请求对象 HttpPost httpPost = new HttpPost("http://172.20.136.5:8080/2016_05_27_server/login"); // 注意Post请求需要进行如下操作 // 集合类型为NameValuePair 或者NameValuePair的子类 // NameValuePair 与 Hashtabl与类似 线程安全的 key value不能为null HashMap线程不安全的 // 键值对 List<NameValuePair> list = new ArrayList<NameValuePair>(); // 给list添加值 // html <form><input ……> </form> list.add(new BasicNameValuePair("uname", "张三")); list.add(new BasicNameValuePair("pwd", "admin")); // 创建发送的HttpEntity对象(客户端给服务端发送的对象) HttpEntity requestEntity = new UrlEncodedFormEntity(list, "gbk");// 参数二 // 处理中文乱码 httpPost.setEntity(requestEntity); // 3,执行请求 HttpResponse response = httpClient.execute(httpPost); // 4,得到响应码 int code = response.getStatusLine().getStatusCode(); if (code == 200) { // 5,得到响应的HttpEntity对象（服务端响应回来的） HttpEntity responseEntity = response.getEntity(); // 方法一 bReader = new BufferedReader(new InputStreamReader(responseEntity.getContent(), "gbk")); String line = null; while ((line = bReader.readLine()) != null) { System.out.println(line); } } } catch (UnsupportedEncodingException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ClientProtocolException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { if (bReader != null) { try { bReader.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } }
通过HttpConnection发送POST请求:
/** * POST请求获取数据 */ public static String postDownloadJson(String path){ URL url = null; try { url = new URL(path); HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection(); httpURLConnection.setRequestMethod("POST");// 提交模式 // conn.setConnectTimeout(10000);//连接超时 单位毫秒 // conn.setReadTimeout(2000);//读取超时 单位毫秒 // 发送POST请求必须设置如下两行 httpURLConnection.setDoOutput(true); httpURLConnection.setDoInput(true); // 获取URLConnection对象对应的输出流 PrintWriter printWriter = new PrintWriter(httpURLConnection.getOutputStream()); // 发送请求参数 printWriter.write("id=8203");//post的参数 xx=xx&yy=yy // flush输出流的缓冲 printWriter.flush(); //开始获取数据 BufferedInputStream bis = new BufferedInputStream(httpURLConnection.getInputStream()); ByteArrayOutputStream bos = new ByteArrayOutputStream(); int len; byte[] arr = new byte[1024]; while((len=bis.read(arr))!= -1){ bos.write(arr,0,len); bos.flush(); } bos.close(); return bos.toString("utf-8"); } catch (Exception e) { e.printStackTrace(); } return null; }
其实raw方式使用的是纯字符串的数据上传方式，所以在POST之前，可能需要手工的把一些json/text/xml格式的数据转换成字符串，是一种post原始请求，区别于form-data这种常用的key-value方式。
/** * post请求之raw请求 */ public static void httpTest() throws ClientProtocolException, IOException { String url = "http://114.55.31.79:7070/app/in/getTipsList.mou"; String json = "{\"page\":\"1\"}";//参数 HttpClient httpClient = new DefaultHttpClient(); HttpPost post = new HttpPost(url); StringEntity postingString = new StringEntity(json);// json传递 post.setEntity(postingString); post.setHeader("Content-type", "application/json");//请求头 post.setHeader("X_version", "1"); HttpResponse response = httpClient.execute(post); String content = EntityUtils.toString(response.getEntity()); // Log.i("test",content); System.out.println(content); }
