Android网络连接之HttpURLConnection和HttpClient

╰半夏微凉° 2022-08-14 03:38 181阅读 0赞

**1.概念**

HTTP 协议可能是现在 Internet 上使用得最多、最重要的协议了，越来越多的 Java 应用程序需要直接通过 HTTP 协议来访问网络资源。在 JDK 的 java.net 包中已经提供了访问 HTTP 协议的基本功能：HttpURLConnection。但是对于大部分应用程序来说，JDK 库本身提供的功能还不够丰富和灵活。

除此之外，在Android中，androidSDK中集成了Apache的HttpClient模块，用来提供高效的、最新的、功能丰富的支持 HTTP 协议工具包，并且它支持 HTTP 协议最新的版本和建议。使用HttpClient可以快速开发出功能强大的Http程序。

**2.区别**

HttpClient是个很不错的开源框架，封装了访问http的请求头，参数，内容体，响应等等，

HttpURLConnection是java的标准类，什么都没封装，用起来太原始，不方便，比如**重访问的自定义**，以及一些高级功能等。

<table> 
 <tbody> 
 <tr> 
 <th>&nbsp;</th> 
 <th> URLConnection </th> 
 <th> HTTPClient </th> 
 </tr> 
 <tr> 
 <th> Proxies and SOCKS </th> 
 <td> Full support in Netscape browser, appletviewer, and applications (SOCKS: Version 4 only); no additional limitations from security policies. </td> 
 <td> Full support (SOCKS: Version 4 and 5); limited in applets however by security policies; in Netscape can't pick up the settings from the browser. </td> 
 </tr> 
 <tr> 
 <th> Authorization </th> 
 <td> Full support for Basic Authorization in Netscape (can use info given by the user for normal accesses outside of the applet); no support in appletviewer or applications. </td> 
 <td> Full support everywhere; however cannot access previously given info from Netscape, thereby possibly requesting the user to enter info (s)he has already given for a previous access. Also, you can add/implement additional authentication mechanisms yourself. </td> 
 </tr> 
 <tr> 
 <th> Methods </th> 
 <td> Only has GET and POST. </td> 
 <td> Has HEAD, GET, POST, PUT, DELETE, TRACE and OPTIONS, plus any arbitrary method. </td> 
 </tr> 
 <tr> 
 <th> Headers </th> 
 <td> Currently you can only set any request headers if you are doing a POST under Netscape; for GETs and the JDK you can't set any headers.&nbsp; Under Netscape 3.0 you can read headers only if the resource was returned with a Content-length header; if no Content-length header was returned, or under previous versions of Netscape, or using the JDK no headers can be read. </td> 
 <td> Allows any arbitrary headers to be sent and received. </td> 
 </tr> 
 <tr> 
 <th> Automatic Redirection Handling </th> 
 <td> Yes. </td> 
 <td> Yes (as allowed by the HTTP/1.1 spec). </td> 
 </tr> 
 <tr> 
 <th> Persistent Connections </th> 
 <td> No support currently in JDK; under Netscape uses HTTP/1.0 Keep-Alive's. </td> 
 <td> Supports HTTP/1.0 Keep-Alive's and HTTP/1.1 persistence. </td> 
 </tr> 
 <tr> 
 <th> Pipelining of Requests </th> 
 <td> No. </td> 
 <td> Yes. </td> 
 </tr> 
 <tr> 
 <th> Can handle protocols other than HTTP </th> 
 <td> Theoretically; however only http is currently implemented. </td> 
 <td> No. </td> 
 </tr> 
 <tr> 
 <th> Can do HTTP over SSL (https) </th> 
 <td> Under Netscape, yes. Using Appletviewer or in an application, no. </td> 
 <td> No (not yet). </td> 
 </tr> 
 <tr> 
 <th> Source code available </th> 
 <td> No. </td> 
 <td> Yes. </td> 
 </tr> 
 </tbody> 
</table>

**3.案例**

**URLConnection**

![复制代码][copycode.gif]

String urlAddress = "http://192.168.1.102:8080/AndroidServer/login.do";  
        URL url;  
        HttpURLConnection uRLConnection;  
        public UrlConnectionToServer(){  
      
        }

//向服务器发送get请求
        public String doGet(String username,String password){  
            String getUrl = urlAddress + "?username="+username+"&password="+password;  
            try {  
                url = new URL(getUrl);  
                uRLConnection = (HttpURLConnection)url.openConnection();  
                InputStream is = uRLConnection.getInputStream();  
                BufferedReader br = new BufferedReader(new InputStreamReader(is));  
                String response = "";  
                String readLine = null;  
                while((readLine =br.readLine()) != null){  
                    //response = br.readLine();  
                    response = response + readLine;  
                }  
                is.close();  
                br.close();  
                uRLConnection.disconnect();  
                return response;  
            } catch (MalformedURLException e) {  
                e.printStackTrace();  
                return null;  
            } catch (IOException e) {  
                e.printStackTrace();  
                return null;  
            }  
        }

//向服务器发送post请求
        public String doPost(String username,String password){  
            try {  
                url = new URL(urlAddress);  
                uRLConnection = (HttpURLConnection)url.openConnection();  
                uRLConnection.setDoInput(true);  
                uRLConnection.setDoOutput(true);  
                uRLConnection.setRequestMethod("POST");  
                uRLConnection.setUseCaches(false);  
                uRLConnection.setInstanceFollowRedirects(false);  
                uRLConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");  
                uRLConnection.connect();  
                  
                DataOutputStream out = new DataOutputStream(uRLConnection.getOutputStream());  
                String content = "username="+username+"&password="+password;  
                out.writeBytes(content);  
                out.flush();  
                out.close();  
                  
                InputStream is = uRLConnection.getInputStream();  
                BufferedReader br = new BufferedReader(new InputStreamReader(is));  
                String response = "";  
                String readLine = null;  
                while((readLine =br.readLine()) != null){  
                    //response = br.readLine();  
                    response = response + readLine;  
                }  
                is.close();  
                br.close();  
                uRLConnection.disconnect();  
                return response;  
            } catch (MalformedURLException e) {  
                e.printStackTrace();  
                return null;  
            } catch (IOException e) {  
                e.printStackTrace();  
                return null;  
            }  
        }

![复制代码][copycode.gif]

**HTTPClient**

![复制代码][copycode.gif]

String urlAddress = "http://192.168.1.102:8080/qualityserver/login.do";  
    public HttpClientServer(){  
              
     }  
          
    public String doGet(String username,String password){  
        String getUrl = urlAddress + "?username="+username+"&password="+password;  
        HttpGet httpGet = new HttpGet(getUrl);  
        HttpParams hp = httpGet.getParams();  
        hp.getParameter("true");  
        //hp.  
        //httpGet.setp  
        HttpClient hc = new DefaultHttpClient();  
        try {  
            HttpResponse ht = hc.execute(httpGet);  
            if(ht.getStatusLine().getStatusCode() == HttpStatus.SC_OK){  
                HttpEntity he = ht.getEntity();  
                InputStream is = he.getContent();  
                BufferedReader br = new BufferedReader(new InputStreamReader(is));  
                String response = "";  
                String readLine = null;  
                while((readLine =br.readLine()) != null){  
                    //response = br.readLine();  
                    response = response + readLine;  
                }  
                is.close();  
                br.close();  
                  
                //String str = EntityUtils.toString(he);  
                System.out.println("========="+response);  
                return response;  
            }else{  
                return "error";  
            }  
        } catch (ClientProtocolException e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
            return "exception";  
        } catch (IOException e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
            return "exception";  
        }      
    }  
      
    public String doPost(String username,String password){  
        //String getUrl = urlAddress + "?username="+username+"&password="+password;  
        HttpPost httpPost = new HttpPost(urlAddress);  
        List params = new ArrayList();  
        NameValuePair pair1 = new BasicNameValuePair("username", username);  
        NameValuePair pair2 = new BasicNameValuePair("password", password);  
        params.add(pair1);  
        params.add(pair2);  
          
        HttpEntity he;  
        try {  
            he = new UrlEncodedFormEntity(params, "gbk");  
            httpPost.setEntity(he);  
              
        } catch (UnsupportedEncodingException e1) {  
            // TODO Auto-generated catch block  
            e1.printStackTrace();  
        }   
          
        HttpClient hc = new DefaultHttpClient();  
        try {  
            HttpResponse ht = hc.execute(httpPost);  
            //连接成功  
            if(ht.getStatusLine().getStatusCode() == HttpStatus.SC_OK){  
                HttpEntity het = ht.getEntity();  
                InputStream is = het.getContent();  
                BufferedReader br = new BufferedReader(new InputStreamReader(is));  
                String response = "";  
                String readLine = null;  
                while((readLine =br.readLine()) != null){  
                    //response = br.readLine();  
                    response = response + readLine;  
                }  
                is.close();  
                br.close();  
                  
                //String str = EntityUtils.toString(he);  
                System.out.println("=========&&"+response);  
                return response;  
            }else{  
                return "error";  
            }  
        } catch (ClientProtocolException e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
            return "exception";  
        } catch (IOException e) {  
            // TODO Auto-generated catch block  
            e.printStackTrace();  
            return "exception";  
        }     
    }

![复制代码][copycode.gif]

**servlet端json转化：**

![复制代码][copycode.gif]

resp.setContentType("text/json"); 
 resp.setCharacterEncoding("UTF-8"); 
 toDo = new ToDo(); 
 List<UserBean> list = new ArrayList<UserBean>(); 
 list = toDo.queryUsers(mySession); 
 String body; 
 
 //设定JSON 
 JSONArray array = new JSONArray(); 
 for(UserBean bean : list) 
 { 
 JSONObject obj = new JSONObject(); 
 try 
 { 
 obj.put("username", bean.getUserName()); 
 obj.put("password", bean.getPassWord()); 
 }catch(Exception e){} 
 array.add(obj); 
 } 
 pw.write(array.toString()); 
 System.out.println(array.toString());

![复制代码][copycode.gif]

**android端接收：**

![复制代码][copycode.gif]

String urlAddress = "http://192.168.1.102:8080/qualityserver/result.do"; 
 String body = 
 getContent(urlAddress); 
 JSONArray array = new JSONArray(body); 
 for(int i=0;i<array.length();i++) 
 { 
 obj = array.getJSONObject(i); 
 sb.append("用户名:").append(obj.getString("username")).append("\t"); 
 sb.append("密码:").append(obj.getString("password")).append("\n"); 
 
 HashMap<String, Object> map = new HashMap<String, Object>(); 
 try { 
 userName = obj.getString("username"); 
 passWord = obj.getString("password"); 
 } catch (JSONException e) { 
 e.printStackTrace(); 
 } 
 map.put("username", userName); 
 map.put("password", passWord); 
 listItem.add(map); 
 
 } 
 
 } catch (Exception e) { 
 // TODO Auto-generated catch block 
 e.printStackTrace(); 
 } 
 
 if(sb!=null) 
 { 
 showResult.setText("用户名和密码信息："); 
 showResult.setTextSize(20); 
 } else 
 extracted(); 
 
 //设置adapter 
 SimpleAdapter simple = new SimpleAdapter(this,listItem, 
 android.R.layout.simple_list_item_2, 
 new String[]{"username","password"}, 
 new int[]{android.R.id.text1,android.R.id.text2}); 
 listResult.setAdapter(simple); 
 
 listResult.setOnItemClickListener(new OnItemClickListener() { 
 @Override 
 public void onItemClick(AdapterView<?> parent, View view, 
 int position, long id) { 
 int positionId = (int) (id+1); 
 Toast.makeText(MainActivity.this, "ID："+positionId, Toast.LENGTH_LONG).show(); 
 
 } 
 }); 
 } 
 private void extracted() { 
 showResult.setText("没有有效的数据！"); 
 } 
 //和服务器连接 
 private String getContent(String url)throws Exception{ 
 StringBuilder sb = new StringBuilder(); 
 HttpClient client =new DefaultHttpClient(); 
 HttpParams httpParams =client.getParams(); 
 
 HttpConnectionParams.setConnectionTimeout(httpParams, 3000); 
 HttpConnectionParams.setSoTimeout(httpParams, 5000); 
 HttpResponse response = client.execute(new HttpGet(url)); 
 HttpEntity entity =response.getEntity(); 
 
 if(entity !=null){ 
 BufferedReader reader = new BufferedReader(new InputStreamReader 
 (entity.getContent(),"UTF-8"),8192); 
 String line =null; 
 while ((line= reader.readLine())!=null){ 
 sb.append(line +"\n"); 
 } 
 reader.close(); 
 } 
 return sb.toString(); 
 }

[copycode.gif]: /images/20220810/763af0f35a084016b91e03d1642cff5c.png