面试篇--android下网络通讯机制(三种网络通讯方式)
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HttpClient
HttpClient是Apache对java中的HttpURLClient接口的封装,主要引用org.apache.http.**。Google在2.3版本之前推荐使用HttpClient,因为这个封装包安全性高,bug较少。
使用方法:
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.util.ArrayList;import java.util.List;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.HttpStatus;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.HttpGet;import org.apache.http.client.methods.HttpPost;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.message.BasicNameValuePair;public class HttpClientUtils { private static HttpClient httpClient; private static HttpClientUtils instance = null; public static synchronized HttpClientUtils getInstance() { if (instance == null) { instance = new HttpClientUtils(); } return instance; } private HttpClientUtils() { // 学习volley请求队列,HttpClient使用单例模式 if (httpClient == null) { httpClient = new DefaultHttpClient(); } } /** * 以get方式发送请求,访问接口 * @param uri链接地址 * @return 响应数据 */ private static String doHttpGet(String uri) { BufferedReader reader = null; StringBuffer sb = null; String result = ""; HttpGet request = new HttpGet(uri); try { // 发送请求,得到响应 HttpResponse response = httpClient.execute(request); // 请求成功,statuscode返回200 if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent())); sb = new StringBuffer(); String line = ""; while ((line = reader.readLine()) != null) { sb.append(line); } } } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { if (null != reader) { reader.close(); reader = null; } } catch (IOException e) { e.printStackTrace(); } } if (null != sb) { result = sb.toString(); } return result; } /** * 以post方式发送请求,访问接口 * @param uri链接地址 * @return 响应数据 */ private static String doHttpPost(String uri) { BufferedReader reader = null; StringBuffer sb = null; String result = ""; HttpPost request = new HttpPost(uri); // 保存要传递的参数 List<NameValuePair> params = new ArrayList<NameValuePair>(); // 添加参数 params.add(new BasicNameValuePair("parameter", "以Post方式发送请求")); try { // 设置字符集 HttpEntity entity = new UrlEncodedFormEntity(params, "utf-8"); // 请求对象 request.setEntity(entity); // 发送请求 HttpResponse response = httpClient.execute(request); // 请求成功 if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { System.out.println("post success"); reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent())); sb = new StringBuffer(); String line = ""; while ((line = reader.readLine()) != null) { sb.append(line); } } } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { // 关闭流 if (null != reader) { reader.close(); reader = null; } } catch (IOException e) { e.printStackTrace(); } } if (null != sb) { result = sb.toString(); } return result; }}
HttpURLConnection
HttpURLConnection在java.NET下,继承自URLConnection类,相对于HttpClient具有扩展性高、灵活性高,更轻量级的优点,所以Google在2.3版本之后推荐大家使用HttpURLConnection来操作网络请求。
使用方法:
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.ObjectOutputStream;import java.io.OutputStream;import java.net.HttpURLConnection;import java.net.URL;import java.net.URLEncoder;public class HttpURLConnectUtils { private static HttpURLConnectUtils instance = null; public static synchronized HttpURLConnectUtils getInstance() { if (instance == null) { instance = new HttpURLConnectUtils(); } return instance; } private HttpURLConnectUtils() { } // post public String dohttppost(String mUrl) throws IOException { URL url = new URL(mUrl); HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();//初始化创建HttpURLConnection实例 httpURLConnection.setConnectTimeout(5000);//推荐设置网络延时 httpURLConnection.setDoOutput(true); httpURLConnection.setDoInput(true); httpURLConnection.setUseCaches(false); httpURLConnection.setRequestProperty("Content-type", "application/x-java-serialized-object"); httpURLConnection.setRequestMethod("POST"); //设置参数 OutputStream outputStream = httpURLConnection.getOutputStream(); ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream); String params = new String();//这里简单设置参数 params = "name=" + URLEncoder.encode("高冉", "GBK"); objectOutputStream.writeBytes(params); objectOutputStream.flush(); objectOutputStream.close(); //接收返回值 //String msg = httpURLConnection.getResponseMessage();// 接收简单string InputStreamReader inputStreamReader = new InputStreamReader(httpURLConnection.getInputStream()); BufferedReader bufferedReader = new BufferedReader(inputStreamReader); StringBuilder builder = new StringBuilder(); for (String s = bufferedReader.readLine(); s != null; s = bufferedReader.readLine()) { builder.append(s); } return builder.toString(); } // get public String dohttpget(String mUrl) throws IOException { URL url = new URL(mUrl); HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection(); httpURLConnection.setConnectTimeout(5000);//推荐设置网络延时 httpURLConnection.setRequestMethod("GET"); httpURLConnection.connect(); // String msg = httpURLConnection.getResponseMessage(); InputStreamReader inputStreamReader = new InputStreamReader(httpURLConnection.getInputStream()); BufferedReader bufferedReader = new BufferedReader(inputStreamReader); StringBuilder builder = new StringBuilder(); for (String s = bufferedReader.readLine(); s != null; s = bufferedReader.readLine()) { builder.append(s); } return builder.toString(); }}
还需要注意一些细节:
1、post与get区别在于post将参数置于请求数据中,get则跟在url链接后面。
2、大文件下载操作要置于sd卡中,不要放在手机内存中操作,而且需要边读边写,不要使用Buffered做缓存。
三、我们看一个简单的socket编程,实现服务器回发客户端信息。
下面用个例子来说明:
A、客户端:
新建Android项目工程:SocketForAndroid(这个随意起名字了吧,我是以这个建立的!)
下面是main_activity.xml的代码:
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<?xml version=
"1.0"
encoding=
"utf-8"
?>
<LinearLayout xmlns:android=
"http://schemas.android.com/apk/res/android"
android:layout_width=
"fill_parent"
android:layout_height=
"fill_parent"
android:orientation=
"vertical"
>
<TextView
android:layout_width=
"fill_parent"
android:layout_height=
"wrap_content"
android:text=
"@string/hello"
/>
<EditText
android:id=
"@+id/message"
android:layout_width=
"match_parent"
android:layout_height=
"wrap_content"
android:hint=
"@string/hint"
/>
<Button
android:id=
"@+id/send"
android:layout_width=
"fill_parent"
android:layout_height=
"wrap_content"
android:text=
"@string/send"
/>
</LinearLayout>
MainActivity.java的代码入下:
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package
com.yaowen.socketforandroid;
import
android.os.Bundle;
import
android.support.v7.app.AppCompatActivity;
import
android.view.View;
import
android.widget.Button;
import
android.widget.EditText;
import
java.io.BufferedReader;
import
java.io.BufferedWriter;
import
java.io.IOException;
import
java.io.InputStreamReader;
import
java.io.OutputStreamWriter;
import
java.io.PrintWriter;
import
java.net.Socket;
public
class
MainActivity
extends
AppCompatActivity {
private
EditText message;
private
Button send;
@Override
protected
void
onCreate(Bundle savedInstanceState) {
super
.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化两个UI控件
message = (EditText) findViewById(R.id.message);
send = (Button) findViewById(R.id.send);
//设置发送按钮的点击事件响应
send.setOnClickListener(
new
View.OnClickListener() {
@Override
public
void
onClick(View v) {
Socket socket =
null
;
//获取message输入框里的输入的内容
String msg = message.getText().toString() +
"\r\n"
;
try
{
//这里必须是192.168.3.200,不可以是localhost或者127.0.0.1
socket =
new
Socket(
"192.168.3.200"
,
18888
);
PrintWriter out =
new
PrintWriter(
new
BufferedWriter(
new
OutputStreamWriter(
socket.getOutputStream()
)
),
true
);
//发送消息
out.println(msg);
//接收数据
BufferedReader in =
new
BufferedReader(
new
InputStreamReader(
socket.getInputStream()
)
);
//读取接收的数据
String msg_in = in.readLine();
if
(
null
!= msg_in) {
message.setText(msg_in);
System.out.println(msg_in);
}
else
{
message.setText(
"接收的数据有误!"
);
}
//关闭各种流
out.close();
in.close();
}
catch
(IOException e) {
e.printStackTrace();
}
finally
{
try
{
if
(
null
!= socket) {
//socket不为空时,最后记得要把socket关闭
socket.close();
}
}
catch
(IOException e) {
e.printStackTrace();
}
}
}
});
}
}
最后别忘记添加访问网络权限:
<uses-permission android:name="android.permission.INTERNET" />
B、服务端:
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package
service;
import
java.io.BufferedReader;
import
java.io.BufferedWriter;
import
java.io.IOException;
import
java.io.InputStreamReader;
import
java.io.OutputStreamWriter;
import
java.io.PrintWriter;
import
java.net.ServerSocket;
import
java.net.Socket;
public
class
ServerAndroid
implements
Runnable {
@Override
public
void
run() {
Socket socket =
null
;
try
{
ServerSocket server =
new
ServerSocket(
18888
);
// 循环监听客户端链接请求
while
(
true
) {
System.out.println(
"start..."
);
// 接收请求
socket = server.accept();
System.out.println(
"accept..."
);
// 接收客户端消息
BufferedReader in =
new
BufferedReader(
new
InputStreamReader(socket.getInputStream()));
String message = in.readLine();
System.out.println(message);
// 发送消息,向客户端
PrintWriter out =
new
PrintWriter(
new
BufferedWriter(
new
OutputStreamWriter(socket.getOutputStream())),
true
);
out.println(
"Server:"
+ message);
// 关闭流
in.close();
out.close();
}
}
catch
(IOException e) {
e.printStackTrace();
}
finally
{
if
(
null
!= socket) {
try
{
socket.close();
}
catch
(IOException e) {
e.printStackTrace();
}
}
}
}
// 启动服务器
public
static
void
main(String[] args) {
Thread server =
new
Thread(
new
ServerAndroid());
server.start();
}
}
C、启动服务器,控制台会打印出“start...”字符串!
D、运行Android项目文件,如下图:
在输入框里输入如下字符串,点发送按钮:
服务器收到客户端发来的消息并打印到控制台:
0 0
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