网上有非常多样例来演示Android客户端和server端数据怎样实现交互只是这些样例大多比較繁杂,对于刚開始学习的人来说这是不利的。如今介绍几种代码简单、逻辑清晰的交互样例,本篇博客介绍第一种:

        一、server端:

        代码1:加入名为“AndroidServerServlet.java”的文件

package com.ghj.packageofservlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class AndroidServerServlet extends HttpServlet {

private static final long serialVersionUID = 6792396567928634227L;

public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
response.setContentType("text/plain; charset=UTF-8");
request.setCharacterEncoding("UTF-8");
System.err.println(request.getParameter("clientData"));
PrintWriter printWriter = response.getWriter();
printWriter.print("您好Android客户端!");
printWriter.flush();
printWriter.close();
}
}


        代码2:改动名为“web.xml”的文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

<servlet>
<servlet-name>AndroidServerServlet</servlet-name>
<servlet-class>com.ghj.packageofservlet.AndroidServerServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>AndroidServerServlet</servlet-name>
<url-pattern>/AndroidServerServlet</url-pattern>
</servlet-mapping>
</web-app>


        二、Android手机客户端:

        代码1:加入名为“AndroidClientActivity.java”的文件

package com.example.androidclient;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
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.protocol.HTTP;
import org.apache.http.util.EntityUtils;

import android.app.Activity;
import android.os.Bundle;
import android.os.StrictMode;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class AndroidClientActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.android_client);

if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
}

Button sendButton = (Button) findViewById(R.id.send_button);
sendButton.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
HttpPost httpRequest = new HttpPost("http://172.16.99.207:8080/AndroidServer/AndroidServerServlet");
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("clientData", "您好server端!"));
try {
httpRequest.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));//设置请求參数项
HttpClient httpClient = new DefaultHttpClient();
HttpResponse httpResponse = httpClient.execute(httpRequest);//运行请求返回响应
if(httpResponse.getStatusLine().getStatusCode() == 200){//推断是否请求成功
Toast.makeText(AndroidClientActivity.this, EntityUtils.toString(httpResponse.getEntity()), Toast.LENGTH_LONG).show();
}else{
Toast.makeText(AndroidClientActivity.this, "没有获取到Androidserver端的响应!", Toast.LENGTH_LONG).show();
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
});
}
}

        注意:请注意“AndroidClientActivity.java”文件里34、35、36和37这4行代码——假设没有这几行代码,则会出现android.os.NetworkOnMainThreadException异常,常代码2:加入名为“android_client.xml”的文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<Button
android:id="@+id/send_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="@string/hello_server" />

</RelativeLayout>


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