HttpClient模拟HTTP的GET和POST请求

最新推荐文章于 2025-04-04 09:08:05 发布

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本文详细介绍了如何在Android应用中利用Apache HttpClient库实现与服务器的GET和POST请求交互，包括请求参数的编码、服务器端的响应处理以及客户端如何接收并展示服务器返回的数据。

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

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：

[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");

    }
}