HTTP请求-Android

一、HttpClient介绍

HttpClient是用来模拟HTTP请求的，其实实质就是把HTTP请求模拟后发给Web服务器；

Android已经集成了HttpClient，因此可以直接使用；

注：此处HttpClient代码不只可以适用于Android，也可适用于一般的Java程序；

HTTP GET核心代码：

(1)DefaultHttpClient client = new DefaultHttpClient();

(2)HttpGet get = new HttpGet(String url);//此处的URL为http://..../path?arg1=value&....argn=value

(3)HttpResponse response = client.execute(get); //模拟请求

(4)int code = response.getStatusLine().getStatusCode();//返回响应码

(5)InputStream in = response.getEntity().getContent();//服务器返回的数据

HTTP POST核心代码：

(1)DefaultHttpClient client = new DefaultHttpClient();

(2)BasicNameValuePair pair = new BasicNameValuePair(String name,String value);//创建一个请求头的字段，比如content-type,text/plain

(3)UrlEncodedFormEntity entity = new UrlEncodedFormEntity(List<NameValuePair> list,String encoding);//对自定义请求头进行URL编码

(4)HttpPost post = new HttpPost(String url);//此处的URL为http://..../path

(5)post.setEntity(entity);

(6)HttpResponse response = client.execute(post);

(7)int code = response.getStatusLine().getStatusCode(); //返回响应码

(8)InputStream in = response.getEntity().getContent();//服务器返回的数据

在AndroidManifest.xml加入：

< uses-permission android:name="android.permission.INTERNET"/> 

二、服务器端代码

服务器端代码和通过URLConnection发出请求的代码不变：

package org.xiazdong.servlet;    
import java.io.IOException; 
 import java.io.OutputStream;    
import javax.servlet.ServletException; 
 import javax.servlet.annotation.WebServlet;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;    
@WebServlet("/Servlet1")  

public class Servlet1 extends HttpServlet {        
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {          
String nameParameter = request.getParameter("name");          
String ageParameter = request.getParameter("age");          
String name = new String(nameParameter.getBytes("ISO-8859-1"),"UTF-8");          
String age = new String(ageParameter.getBytes("ISO-8859-1"),"UTF-8");          
System.out.println("GET");          
System.out.println("name="+name);          
System.out.println("age="+age);          
response.setCharacterEncoding("UTF-8");          
OutputStream out = response.getOutputStream();//返回数据          
out.write("GET请求成功!".getBytes("UTF-8"));          
out.close();      
}        
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {          request.setCharacterEncoding("UTF-8");          
String name = request.getParameter("name");          
String age  = request.getParameter("age");          
System.out.println("POST");          
System.out.println("name="+name);          
System.out.println("age="+age);          
response.setCharacterEncoding("UTF-8");          
OutputStream out = response.getOutputStream();          
out.write("POST请求成功!".getBytes("UTF-8"));          
out.close();                
}    
} 

三、Android客户端代码

效果如下：

在AndroidManifest.xml加入：

[html]  < uses-permission android:name="android.permission.INTERNET"/>   

MainActivity.java

[java]  package org.xiazdong.network.httpclient;    import java.io.ByteArrayOutputStream;  import java.io.IOException;  import java.io.InputStream;  import java.net.URLEncoder;  import java.util.ArrayList;  import java.util.List;    import org.apache.http.HttpResponse;  import org.apache.http.NameValuePair;  import org.apache.http.client.entity.UrlEncodedFormEntity;  import org.apache.http.client.methods.HttpGet;  import org.apache.http.client.methods.HttpPost;  import org.apache.http.impl.client.DefaultHttpClient;  import org.apache.http.message.BasicNameValuePair;    import android.app.Activity;  import android.os.Bundle;  import android.view.View;  import android.view.View.OnClickListener;  import android.widget.Button;  import android.widget.EditText;  import android.widget.Toast;   

public class MainActivity extends Activity {     

private EditText name, age;     

private Button getbutton, postbutton;     

private OnClickListener listener = new OnClickListener() {         

@Override         

public void onClick(View v) {             

try{                 

if(postbutton==v){                     

/*                      * NameValuePair代表一个HEADER，List<NameValuePair>存储全部的头字段                      * UrlEncodedFormEntity类似于URLEncoder语句进行URL编码                      * HttpPost类似于HTTP的POST请求                      * client.execute()类似于发出请求，并返回Response                      */                     

DefaultHttpClient client = new DefaultHttpClient();                     

List<NameValuePair> list = new ArrayList<NameValuePair>();                     

NameValuePair pair1 = new BasicNameValuePair("name", name.getText().toString());                     

NameValuePair pair2 = new BasicNameValuePair("age", age.getText().toString());                     

list.add(pair1);                     

list.add(pair2);                     

UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list,"UTF-8");                     

HttpPost post = new HttpPost("http://192.168.0.103:8080/Server/Servlet1");                     

post.setEntity(entity);                     

HttpResponse response = client.execute(post);                                           

if(response.getStatusLine().getStatusCode()==200){                         

InputStream in = response.getEntity().getContent();//接收服务器的数据，并在Toast上显示                         

String str = readString(in);                         

Toast.makeText(MainActivity.this, str, Toast.LENGTH_SHORT).show();                                                                         

}                     

else Toast.makeText(MainActivity.this, "POST提交失败", Toast.LENGTH_SHORT).show();                 

}                 

if(getbutton==v){                     

DefaultHttpClient client = new DefaultHttpClient();                     

StringBuilder buf = new StringBuilder("http://192.168.0.103:8080/Server/Servlet1");                     

buf.append("?");                     

buf.append("name="+URLEncoder.encode(name.getText().toString(),"UTF-8")+"&");                     

buf.append("age="+URLEncoder.encode(age.getText().toString(),"UTF-8"));                     

HttpGet get = new HttpGet(buf.toString());                     

HttpResponse response = client.execute(get);                     

if(response.getStatusLine().getStatusCode()==200){                         

InputStream in = response.getEntity().getContent();                         

String str = readString(in);                         

Toast.makeText(MainActivity.this, str, Toast.LENGTH_SHORT).show();                     

}                     

else Toast.makeText(MainActivity.this, "GET提交失败", Toast.LENGTH_SHORT).show();                 

}             

}             

catch(Exception e){}         

}     

};     

@Override     

public void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.main);          name = (EditText) this.findViewById(R.id.name);          age = (EditText) this.findViewById(R.id.age);          getbutton = (Button) this.findViewById(R.id.getbutton);          postbutton = (Button) this.findViewById(R.id.postbutton);          getbutton.setOnClickListener(listener);          postbutton.setOnClickListener(listener);      }      protected String readString(InputStream in) throws Exception {          byte[]data = new byte[1024];          int length = 0;          ByteArrayOutputStream bout = new ByteArrayOutputStream();          while((length=in.read(data))!=-1){              bout.write(data,0,length);          }          return new String(bout.toByteArray(),"UTF-8");                }  }