HTTPClient和URLConnection核心区别分析

首先：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。
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。

其次：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。

HttpClient就是一个增强版的HttpURLConnection，HttpURLConnection可以做的事情HttpClient全部可以做；HttpURLConnection没有提供的有些功能，HttpClient也提供了，但它只是关注于如何发送请求、接收响应，以及管理HTTP连接。

使用HttpClient发送请求、接收响应很简单，只要如下几步即可：
1.创建HttpClient对象。
2.如果需要发送GET请求，创建HttpGet对象；如果需要发送POST请求，创建HttpPost对象。
3.如果需要发送请求参数，可调用HttpGet、HttpPost共同的setParams(HetpParams params)方法来添加请求参数；对于HttpPost对象而言，也可调用setEntity(HttpEntity entity)方法来设置请求参数。
4.调用HttpClient对象的execute(HttpUriRequest request)发送请求，执行该方法返回一个HttpResponse。
5.调用HttpResponse的getAllHeaders()、getHeaders(String name)等方法可获取服务器的响应头；调用HttpResponse的getEntity()方法可获取HttpEntity对象，该对象包装了服务器的响应内容。程序可通过该对象获取服务器的响应内容。

具体对比如下：HTTPClient

String url = "http://192.168.1.100:8080";
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");
//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);
return response;
}else{
return "error";
}
} catch (ClientProtocolException e) {
e.printStackTrace();
return "exception";
} catch (IOException e) {
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) {
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);
return response;
}else{
return "error";
}
} catch (ClientProtocolException e) {
e.printStackTrace();
return "exception";
} catch (IOException e) {
e.printStackTrace();
return "exception";
}
}

HttpURLConnection:

String url = "http://192.168.1.100:8080";
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();
returnnull;
} catch (IOException e) {
e.printStackTrace();
returnnull;
}
}
//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();
returnnull;
} catch (IOException e) {
e.printStackTrace();
returnnull;
}
}

客户端操作：

String url = "http://192.168.1.102:8080";
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) {
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"},
newint[]{android.R.id.text1,android.R.id.text2});
listResult.setAdapter(simple);

listResult.setOnItemClickListener(new OnItemClickListener() {
@Override
publicvoid onItemClick(AdapterView<?> parent, View view,
int position, long id) {
int positionId = (int) (id+1);
Toast.makeText(MainActivity.this, "ID："+positionId, Toast.LENGTH_LONG).show();
}
});
}
privatevoid 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();
}