网络编程

package com.example.testsometing;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.TextView;

public class MainActivity extends Activity {

Handler handler ;
TextView tv_response;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

tv_response = (TextView) this.findViewById(R.id.response);
handler = new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case 1:
tv_response.setText(msg.obj.toString());
break;
default:
break;
}
}
};

new Thread(new Runnable() {
@Override
public void run() {

HttpURLConnection connection = null;
try {
URL url = new URL("http://www.baidu.com");
connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");//代表我想要获取，POST代表我想要传递参数给网站
connection.setConnectTimeout(3000);
connection.setReadTimeout(8000);
//connection.setRequestMethod("POST");
//DataOutputStream out = new DataOutputStream(Connection.getOutputStream());
//out.writeBytes("username=admin&password=123456");

InputStream in = connection.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
StringBuilder response = new StringBuilder();

String line;
while((line=reader.readLine()) != null){
response.append(line);
}

Message msg = new Message();
msg.what = 1;
msg.obj = response;
handler.sendMessage(msg);

} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
}
}

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

package com.example.testsometing;

import java.io.IOException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.TextView;

public class MainActivity extends Activity {

Handler handler ;
TextView tv_response;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

tv_response = (TextView) this.findViewById(R.id.response);
handler = new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case 1:
tv_response.setText(msg.obj.toString());
break;
default:
break;
}
}
};

new Thread(new Runnable() {
@Override
public void run() {
try {
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet("http://www.baidu.com");
HttpResponse httpResponse = httpClient.execute(httpGet);
/*
HttpGet httpPost = new HttpPost("http://www.baidu.com");
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("username","admin"));
params.add(new BasicNameValuePair("password","123456"));
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(params,"utf-8");
httpPost.setEntity(entity);
HttpResponse httpResponse = httpClient.execute(httpPost);

*/
String response;
if(httpResponse.getStatusLine().getStatusCode() == 200){
//请求和相应都成功
HttpEntity entity = httpResponse.getEntity();
response = EntityUtils.toString(entity,"utf-8");
}
else{
response = "error";
}
Message msg = new Message();
msg.what = 1;
msg.obj = response;
handler.sendMessage(msg);

} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

}
}

).start();
}
}

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

HttpUrlConnection更新 2016/02/24

String url = "http://imgsrc.baidu.com/forum/pic/item/3582724c510fd9f9e10ab386252dd42a2934a4bf.jpg";
new  MyThread(url, iv, handler).start();

public class MyThread extends Thread {
private ImageView iv;
private Handler handler;
String url;
public MyThread(String url, ImageView iv, Handler handler) {
this.url = url;
this.iv = iv;
this.handler = handler;
}

@Override
public void run() {

try {
URL httpUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection)httpUrl.openConnection();
conn.setReadTimeout(5000);
conn.setRequestMethod("GET");
conn.setDoInput(true);

InputStream in = conn.getInputStream();
FileOutputStream out = null;
String fileName = String.valueOf(System.currentTimeMillis());
File downloadFile = null;

//判断SD卡是否挂载
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
File parent = Environment.getExternalStorageDirectory();
downloadFile = new File(parent, fileName);
out = new FileOutputStream(downloadFile);
}

byte[] b =new byte[2*1024];
int len;
if (out!=null) {
while ((len=in.read(b))!=-1) {
out.write(b,0,len);
}
}

if (downloadFile != null) {
final Bitmap bmp = BitmapFactory.decodeFile(downloadFile.getAbsolutePath());
handler.post(new Runnable() {

@Override
public void run() {
iv.setImageBitmap(bmp);

}
});
}

} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

}
}

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