http 网络请求 下载图片

访问网络最主要的也就是 http协议了。

http协议很简单，但是很重要。

直接上代码了，里面都是1个代码块 代码块的，用哪一部分直接拷出去用就好了。


1.访问网络用 get 和 post 自己组拼提交参数 ，httpclient 方式提交

2.上传 和 下载

3.比如访问服务器后 返回来的 xml 和 json 的简单解析方法

<p>HttpClient其实是一个interface类型，HttpClient封装了对象需要执行的Http请求、身份验证、连接管理和其它特性</p>
<p>HttpClient有三个已知的实现类分别是：</p>
<p>AbstractHttpClient, AndroidHttpClient, DefaultHttpClient<br>
</p>
<p> AndroidHttpClient是对HttpClient的包装，内部带访问连接器，并设置为可以多线程使用，</p>

String  path = "http://192.168.13.1";    String  username ="ll";    String  pwd="123";         /**   get 组拼    */    public void  httpGet()            throws Exception {             String param1 = URLEncoder.encode(username);        String param2 = URLEncoder.encode(pwd);        URL url = new URL(path + "?name=" + param1 + "&password=" + param2);        HttpURLConnection conn = (HttpURLConnection) url.openConnection();        conn.setRequestMethod("GET");        conn.setReadTimeout(5000);        // 数据并没有发送给服务器        // 获取服务器返回的流信息        InputStream in = conn.getInputStream();        byte[] result = StreamTool.getBytes(in);         //return new String(result);    }                   /** post  组拼   */    public  void  httpPost() throws Exception {             URL url = new URL(path);        String param1 = URLEncoder.encode(username);        String param2 = URLEncoder.encode(pwd);        //开始连接        HttpURLConnection conn = (HttpURLConnection) url.openConnection();        String data = "username=" + param1 + "&password=" + param2;        //设置方式 post        conn.setRequestMethod("POST");        //timeout  5000        conn.setConnectTimeout(5000);        // 设置 http协议可以向服务器写数据        conn.setDoOutput(true);        // 设置http协议的消息头        conn.setRequestProperty("Content-Type","application/x-www-form-urlencoded");        conn.setRequestProperty("Content-Length",  String.valueOf(data.length()));        // 把我们准备好的data数据写给服务器        OutputStream os = conn.getOutputStream();        os.write(data.getBytes());        // httpurlconnection 底层实现 outputstream 是一个缓冲输出流        // 只要我们获取任何一个服务器返回的信息 , 数据就会被提交给服务器 , 得到服务器返回的流信息        int code = conn.getResponseCode();        if (code == 200) {            InputStream is = conn.getInputStream();            byte[] result = StreamTool.getBytes(is);            String ss= new String(result);        }             }              /**   httpclient  get   */    public void httpClentGet () throws Exception{        //获取到一个浏览器的实例         HttpClient client = new DefaultHttpClient();        //准备请求的地址         String param1 = URLEncoder.encode(username);        String param2 = URLEncoder.encode(pwd);        HttpGet httpGet = new HttpGet(path + "?name=" + param1 + "&password=" + param2);        //敲回车 发请求         HttpResponse  ressponse = client.execute(httpGet);        int code = ressponse.getStatusLine().getStatusCode();        if( code ==  200){            InputStream is  =ressponse.getEntity().getContent();            //byte[] result = StreamTool.getBytes(is);                     }     }              //  不需要的时候关闭 httpclient   client.getConnectionManager().shutdown();    /**    httpclient  post **/    public  void httpClentPost() throws Exception{          //1. 获取到一个浏览器的实例         HttpClient client = new DefaultHttpClient();        HttpPost httppost = new HttpPost(path);        // 键值对  BasicNameValuePair        List<namevaluepair> parameters = new ArrayList<namevaluepair>();        parameters.add(new BasicNameValuePair("username", username));        parameters.add(new BasicNameValuePair("pwd", pwd));        UrlEncodedFormEntity entity = new UrlEncodedFormEntity(parameters, "utf-8");        //3.设置post请求的数据实体         httppost.setEntity(entity);        //4. 发送数据给服务器        HttpResponse  ressponse = client.execute(httppost);        int code = ressponse.getStatusLine().getStatusCode();        if(code == 200){            InputStream is  =ressponse.getEntity().getContent();            byte[] result = StreamTool.getBytes(is);                         //return new String(result);        }             }              /*** 下载一个东西    ***/    public void getFileData(Context context){                         try {             HttpClient client = new DefaultHttpClient();             HttpGet httpGet = new HttpGet(path);             //执行             HttpResponse  ressponse = client.execute(httpGet);             int code = ressponse.getStatusLine().getStatusCode();                                                 if(code == HttpStatus.SC_OK){                        InputStream in =ressponse.getEntity().getContent();                        //图片 //                      Bitmap bitmap = BitmapFactory.decodeStream(in);//                      in.close();                                                 //文件什么的比如读取了是要写在本地的                        //小文件直接读取   大文件读取一点写一点                        //byte[] result = StreamTool.getBytes(in);                        //                                                  //这里可以得到文件的类型 如image/jpg /zip /tiff 等等 但是发现并不是十分有效，有时明明后缀是.rar但是取到的是null，这点特别说明                        System.out.println(ressponse.getEntity().getContentType());                        //可以判断是否是文件数据流                        System.out.println(ressponse.getEntity().isStreaming());                        //设置本地保存的文件                        //File storeFile = new File("c:/0431la.zip");                          String path="sdcard/aa.txt";                        FileOutputStream output = context.openFileOutput(path, context.MODE_PRIVATE);                        //得到网络资源并写入文件                        InputStream input = ressponse.getEntity().getContent();                        byte b[] = new byte[1024];                        int j = 0;                        while( (j = input.read(b))!=-1){                             output.write(b,0,j);                        }                        output.flush();                        output.close();                      }          } catch (Exception e) {            // TODO: handle exception        }                   }              /**     * 提交数据给服务器 带一个文件      * @param filepath 文件在手机上的路径      */    public void PostData(String filepath) throws Exception{                 // 实例化上传数据的 数组  part [] username  pwd        Part[] parts = {                  new StringPart("username", username),                   new StringPart("pwd", pwd),                   new FilePart("file", new File(filepath))                  };                 PostMethod file_Post = new PostMethod(path);        //                              多种类型的数据实体        file_Post.setRequestEntity(new MultipartRequestEntity(parts, file_Post.getParams()));        //创建 client        org.apache.commons.httpclient.HttpClient client = new org.apache.commons.httpclient.HttpClient();        //timeout        client.getHttpConnectionManager().getParams().setConnectionTimeout(5000);        //执行        int status = client.executeMethod(file_Post);                 if(status==200){                               }     }              //传送文件    public void setFile() throws Exception{          HttpClient httpclient = new DefaultHttpClient();            HttpPost httppost = new HttpPost("http://192.168.1.1");            File file = new File(path);            InputStreamEntity reqEntity = new InputStreamEntity(                    new FileInputStream(file), -1);            reqEntity.setContentType("binary/octet-stream");            reqEntity.setChunked(true);                  // FileEntity entity = new FileEntity(file, "binary/octet-stream");            httppost.setEntity(reqEntity);            System.out.println("executing request " + httppost.getRequestLine());            HttpResponse response = httpclient.execute(httppost);                   if(response.getStatusLine().getStatusCode() == 200){                                     }             }                        /** 1.     *  一般访问了就会返回来1个  webservice     *  pull解析访问webservice 返回来的xml     *   **/         public void  pullJX(byte[]  bb)  throws Exception{        // byte[] bb = EntityUtils.toByteArray(response.getEntity());         XmlPullParser pullParser = Xml.newPullParser();         pullParser.setInput(new ByteArrayInputStream(bb), "UTF-8");         int event = pullParser.getEventType();            List<object> info;         while(event != XmlPullParser.END_DOCUMENT){                  switch (event) {                       case XmlPullParser.START_DOCUMENT:                        info = new ArrayList<object>();                        break;                                                case XmlPullParser.START_TAG:                                                        if("aa".equals(pullParser.getName())){                            String id = pullParser.nextText().toString();                         }                        break;                                                case XmlPullParser.END_TAG:                          if("aa".equals(pullParser.getName())){                                                          }                      break;                  }            event = pullParser.next();          }    }          /**2.     *  解析 json  数据 [{id:"001",name:"lilei",age:"20"},{id:"002",name:"zhangjia",age:"30"}]       */    private static List parseJSON(InputStream  in) throws Exception{        byte[] data = StreamTool.getBytes(in);        String s =new String(data);        // 转换成  json 数组对象   [{"001","ll","20"},{"002","zj","30"},]        JSONArray json = new JSONArray(s);            for (int i = 0; i < json.length() ; i++) {                  JSONObject j = json.getJSONObject(i);                  String aa1 = j.getString("id");                  String aa2 = j.getString("name");                  String aa3 = j.getString("age");            }          return  null;       }