Android入門:用HttpClient模擬HTTP的GET和POST請求

一、HttpClient介紹

HttpClient是用來模擬HTTP請求的,其實實質就是把HTTP請求模擬後發給Web服務器;

Android已經集成瞭HttpClient,因此可以直接使用;

註:此處HttpClient代碼不隻可以適用於Android,也可適用於一般的Java程序;

HTTP GET核心代碼:

(1)DefaultHttpClient client = new DefaultHttpClient();
(2)HttpGet get = new HttpGet(String url);//此處的URL為http://…./path?arg1=value&….argn=value
(3)HttpResponse response = client.execute(get); //模擬請求
(4)int code = response.getStatusLine().getStatusCode();//返回響應碼
(5)InputStream in = response.getEntity().getContent();//服務器返回的數據

HTTP POST核心代碼:

(1)DefaultHttpClient client = new DefaultHttpClient();
(2)BasicNameValuePair pair = new BasicNameValuePair(String name,String value);//創建一個請求頭的字段,比如content-type,text/plain
(3)UrlEncodedFormEntity entity = new UrlEncodedFormEntity(List<NameValuePair> list,String encoding);//對自定義請求頭進行URL編碼
(4)HttpPost post = new HttpPost(String url);//此處的URL為http://…./path
(5)post.setEntity(entity);
(6)HttpResponse response = client.execute(post);
(7)int code = response.getStatusLine().getStatusCode();
(8)InputStream in = response.getEntity().getContent();//服務器返回的數據

二、服務器端代碼

服務器端代碼和通過URLConnection發出請求的代碼不變:

[java] 
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();//返回數據 
        out.write("GET請求成功!".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請求成功!".getBytes("UTF-8")); 
        out.close(); 
         
    } 
 

 

三、Android客戶端代碼

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代表一個HEADER,List<NameValuePair>存儲全部的頭字段
                     * UrlEncodedFormEntity類似於URLEncoder語句進行URL編碼
                     * HttpPost類似於HTTP的POST請求
                     * client.execute()類似於發出請求,並返回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();//接收服務器的數據,並在Toast上顯示 
                        String str = readString(in); 
                        Toast.makeText(MainActivity.this, str, Toast.LENGTH_SHORT).show(); 
                         
                         
                    } 
                    else Toast.makeText(MainActivity.this, "POST提交失敗", 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提交失敗", 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"); 
         
    } 

作者:xiazdong
 

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