第二十章之HttpClient请求

Http工作的大致原理：

①客户端连接到Web服务器

②发送HTTP请求

③服务器接受请求并返回HTTP响应

④释放连接TCP连接

⑤客户端浏览器解析HTML内容

⑥客户端与服务端断开连接

步骤：

①创建一个类继承Thread

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

parameters.add(new BasicNameValuePair("name","张三"));

②创建HttpClien请求执行t实例 HttpClient client=new DefaultHttpClient();

③设置请求方式

HttpPost request=new HttpPost("..................");

④绑定参数

UrlEncodedFormEntity entity=new UrlEncodedFormEntity(parameters);

将绑定的参数设置到请求对象当中

request.setEntity(entity);

HttpResponse response=client.excute(request);

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

//获取服务器端的数据

String str = EntityUtils.toString(response.getEntity());

//从消息池中获取消息对象。

Message msg = handler.obtainMessage();

//创建数据存放对象

Bundle bundle = new Bundle();

bundle.putString("name", str);

//把数据对象放到消息对象当中

msg.setData(bundle);

//将消息对象发送到消息队列

handler.sendMessage(msg);

}

上课案例

MainActivity.java

package com.ryan.lsn3_18;

import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {
Button start_btn;
Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
//获取子线程传递来的数据
Bundle bundle = msg.getData();
//根据键获取值
String name = bundle.getString("name");
//更新按钮的文本
start_btn.setText(name);
super.handleMessage(msg);
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
initView();
}
public void initView(){
start_btn = (Button)findViewById(R.id.start_btn);
start_btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
//				MyThread thread = new MyThread();
//启动 线程
//				thread.start();
//创建线程对象
DemoThread thread = new DemoThread();
//启动线程
thread.start();
}
});
}
class DemoThread extends Thread{

@Override
public void run() {
List<NameValuePair> parameters = new ArrayList<NameValuePair>();
parameters.add(new BasicNameValuePair("name", "张三"));
parameters.add(new BasicNameValuePair("password", "123456"));
try {
//请求执行对象
HttpClient client = new DefaultHttpClient();
//设置请求方式
HttpPost request = new HttpPost("http://10.0.2.2:8080/MyServer/DemoServlet");
//绑定参数
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(parameters);
//将绑定的参数设置到请求对象当中
request.setEntity(entity);
//执行请求
HttpResponse response = client.execute(request);
//判断连接是否成功，连接成功为200
if(response.getStatusLine().getStatusCode() == 200){
//获取服务器端的数据
String str = EntityUtils.toString(response.getEntity());
//从消息池中获取消息对象。
Message msg = handler.obtainMessage();
//创建数据存放对象
Bundle bundle = new Bundle();
bundle.putString("name", str);
//把数据对象放到消息对象当中
msg.setData(bundle);
//将消息对象发送到消息队列
handler.sendMessage(msg);
}

} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

}

class MyThread extends Thread{
@Override
public void run() {
try {
String stu = "";
//构造请求地址
URL url = new URL("http://10.0.2.2:8080/MyServer/DemoServlet");
//打开连接
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
//设置服务器可读
conn.setDoInput(true);
//设置连接超时
conn.setConnectTimeout(5000);
//设置请求方式
conn.setRequestMethod("POST");
//请求连接
conn.connect();
//判断是否连接成狗
if(conn.getResponseCode() == HttpURLConnection.HTTP_OK){
//获取服务器端的输入流
InputStream is = conn.getInputStream();
//读取服务器端的数据
byte []buffer = new byte[1024];
int length =0;
while((length = is.read(buffer)) != -1){
stu = new String(buffer, 0, length);
}
}

//从消息池中获取消息对象。
Message msg = handler.obtainMessage();
//创建数据存放对象
Bundle bundle = new Bundle();
bundle.putString("name", stu);
//把数据对象放到消息对象当中
msg.setData(bundle);
//将消息对象发送到消息队列
handler.sendMessage(msg);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}