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Android客户端与服务端交互

2020-04-11 10:51:38
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本文和大家一起了解了一下android客户端与服务端是怎样交互的,具体内容如下

1.后台使用简单的servlet,支持GET或POST。这个servlet最终返回给前台一个字符串flag,值是true或false,表示登录是否成功。

servlet使用之前需要配置,主义servlet的servlet-name要和servlet-mapping的servlet-name一致,否则找不到路径

我是在myEclipse上创建的一个web service 项目,然后部署到tomcat服务器上以便android客户端访问

<servlet>    <servlet-name>helloWorld</servlet-name>    <servlet-class>com.zhongzhong.wap.action.HelloServlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>helloWorld</servlet-name>    <url-pattern>/queryOrder</url-pattern>  </servlet-mapping>   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;import javax.servlet.http.HttpSession; import com.zhongzhong.wap.bean.UserBean; public class HelloServlet extends HttpServlet {   @Override  protected void doGet(HttpServletRequest req, HttpServletResponse resp)      throws ServletException, IOException {    doPost(req, resp);  }   @Override  protected void doPost(HttpServletRequest req, HttpServletResponse resp)      throws ServletException, IOException {          resp.setContentType(text/html);       PrintWriter out = resp.getWriter();       Boolean flag = false;        String userName = req.getParameter(un);       String password = req.getParameter(pw);       if(userName.equals(htp)&&password.equals(123))      {        flag = true;      }             else flag = false;      System.out.println(userName:+userName+ password:+password);      out.print(flag);       out.flush();       out.close();  } }

2.然后我是在安卓的ADT上创建一个安卓项目,建立两个Activity,分别作为登录界面和登录成功界面。

<relativelayout android:layout_height="match_parent" android:layout_width="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" xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools">   <textview android:id="@+id/textView1" android:layout_alignparenttop="true" android:layout_centerhorizontal="true" android:layout_height="wrap_content" android:layout_margintop="40dp" android:layout_width="wrap_content" android:text="HelloWorld登陆示例">   <edittext android:ems="10" android:hint="请输入账号" android:id="@+id/et_user" android:layout_below="@+id/textView1" android:layout_centerhorizontal="true" android:layout_height="wrap_content" android:layout_margintop="33dp" android:layout_width="wrap_content">     <requestfocus>  </requestfocus></edittext>   <edittext android:ems="10" android:hint="请输入密码" android:id="@+id/et_psw" android:inputtype="textPassword" android:layout_below="@+id/et_user" android:layout_centerhorizontal="true" android:layout_height="wrap_content" android:layout_margintop="40dp" android:layout_width="wrap_content"><button android:id="@+id/btn_login" android:layout_below="@+id/et_psw" android:layout_centerhorizontal="true" android:layout_height="wrap_content" android:layout_margintop="37dp" android:layout_width="wrap_content" android:text="登陆"></button></edittext></textview></relativelayout>   <relativelayout android:layout_height="match_parent" android:layout_width="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=".NaviActivity" xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools">   <textview android:layout_alignparenttop="true" android:layout_centerhorizontal="true" android:layout_height="wrap_content" android:layout_margintop="46dp" android:layout_width="wrap_content" android:text="登陆成功"> </textview></relativelayout>

 3.HTTP的访问公共类,用于处理GET和POST请求。

 package com.example.logindemo; import java.util.ArrayList;import java.util.List;import java.util.Map; import org.apache.http.HttpResponse;import org.apache.http.NameValuePair;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;import org.apache.http.util.EntityUtils; import android.content.Entity;import android.util.Log; public class HttpUtil {  // 创建HttpClient对象  public static HttpClient httpClient = new DefaultHttpClient();  public static final String BASE_URL = http://192.168.3.14:8090/HelloWord/;   /**   *   * @param url   *      发送请求的URL   * @return 服务器响应字符串   * @throws Exception   */  public static String getRequest(String url) throws Exception {    // 创建HttpGet对象。    HttpGet get = new HttpGet(url);    // 发送GET请求    HttpResponse httpResponse = httpClient.execute(get);    // 如果服务器成功地返回响应    if (httpResponse.getStatusLine().getStatusCode() == 200) {      // 获取服务器响应字符串      String result = EntityUtils.toString(httpResponse.getEntity());      return result;    } else {      Log.d(服务器响应代码, (new Integer(httpResponse.getStatusLine()          .getStatusCode())).toString());      return null;    }  }   /**   *   * @param url   *      发送请求的URL   * @param params   *      请求参数   * @return 服务器响应字符串   * @throws Exception   */  public static String postRequest(String url, Map<string, string=""> rawParams)      throws Exception {    // 创建HttpPost对象。    HttpPost post = new HttpPost(url);    // 如果传递参数个数比较多的话可以对传递的参数进行封装    List<namevaluepair> params = new ArrayList<namevaluepair>();    for (String key : rawParams.keySet()) {      // 封装请求参数      params.add(new BasicNameValuePair(key, rawParams.get(key)));    }    // 设置请求参数    post.setEntity(new UrlEncodedFormEntity(params, UTF-8));    // 发送POST请求    HttpResponse httpResponse = httpClient.execute(post);    // 如果服务器成功地返回响应    if (httpResponse.getStatusLine().getStatusCode() == 200) {      // 获取服务器响应字符串      String result = EntityUtils.toString(httpResponse.getEntity());      return result;    }    return null;  }}</namevaluepair></namevaluepair></string,>

4.IntentService服务,用于在后台以队列方式处理耗时操作。

package com.example.logindemo; import java.util.HashMap; import android.app.IntentService;import android.content.Intent;import android.util.Log; public class ConnectService extends IntentService {  private static final String ACTION_RECV_MSG = com.example.logindemo.action.RECEIVE_MESSAGE;   public ConnectService() {    super(TestIntentService);    // TODO Auto-generated constructor stub  }     @Override  protected void onHandleIntent(Intent intent) {    // TODO Auto-generated method stub    /**     * 经测试,IntentService里面是可以进行耗时的操作的      * IntentService使用队列的方式将请求的Intent加入队列,     * 然后开启一个worker thread(线程)来处理队列中的Intent      * 对于异步的startService请求,IntentService会处理完成一个之后再处理第二个      */     Boolean flag = false;     //通过intent获取主线程传来的用户名和密码字符串     String username = intent.getStringExtra(username);     String password = intent.getStringExtra(password);     flag = doLogin(username, password);     Log.d(登录结果, flag.toString());           Intent broadcastIntent = new Intent();     broadcastIntent.setAction(ACTION_RECV_MSG);      broadcastIntent.addCategory(Intent.CATEGORY_DEFAULT);      broadcastIntent.putExtra(result, flag.toString());     sendBroadcast(broadcastIntent);    }      // 定义发送请求的方法   private Boolean doLogin(String username, String password)   {     String strFlag = ;     // 使用Map封装请求参数     HashMap<string, string=""> map = new HashMap<string, string="">();     map.put(un, username);     map.put(pw, password);     // 定义发送请求的URL    String url = HttpUtil.BASE_URL + queryOrder?un= + username + &pw= + password; //GET方式     // String url = HttpUtil.BASE_URL + LoginServlet; //POST方式     Log.d(url, url);     Log.d(username, username);     Log.d(password, password);     try {       // 发送请求       strFlag = HttpUtil.postRequest(url, map); //POST方式 //     strFlag = HttpUtil.getRequest(url); //GET方式       Log.d(服务器返回值, strFlag);     } catch (Exception e) {       // TODO Auto-generated catch block       e.printStackTrace();     }           if(strFlag.trim().equals(true)){       return true;     }else{       return false;     }         } }</string,></string,>

5.在AndroidManifest.xml中注册IntentService。注意uses-permission节点,为程序开启访问网络的权限。 

<!--?xml version=1.0 encoding=utf-8?--><manifest android:versioncode="1" android:versionname="1.0" package="com.example.logindemo" xmlns:android="http://schemas.android.com/apk/res/android">   <uses-sdk android:minsdkversion="8" android:targetsdkversion="18">   <uses-permission android:name="android.permission.INTERNET">               <intent-filter>                  <category android:name="android.intent.category.LAUNCHER">      </category></action></intent-filter>    </activity>         </activity>     <service android:name="com.example.logindemo.ConnectService">    </service>  </application> </uses-permission></uses-sdk></manifest>

6.登陆界面处理,注意

按钮监听事件中,使用Intent将要传递的值传给service。接收广播类中,同样使用Intent将要传递的值传给下一个Activity。在onCreate()中,动态注册接收广播类的实例receiver。在接收广播类中,不要使用完毕后忘记注销接收器,否则会报一个Are you missing a call to unregisterReceiver()? 的异常。 

package com.example.logindemo; import android.os.Bundle;import android.app.Activity;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.content.IntentFilter;import android.util.Log;import android.view.Menu;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 static final String ACTION_RECV_MSG = com.example.logindemo.action.RECEIVE_MESSAGE;  private Button loginBtn;  private EditText et_username;  private EditText et_password;  private String userName;  private String passWord;  private MessageReceiver receiver ;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    initView();    //动态注册receiver      IntentFilter filter = new IntentFilter(ACTION_RECV_MSG);      filter.addCategory(Intent.CATEGORY_DEFAULT);      receiver = new MessageReceiver();      registerReceiver(receiver, filter);  }     private void initView() {    // TODO Auto-generated method stub    et_username = (EditText)findViewById(R.id.et_user);    et_password =( EditText)findViewById(R.id.et_psw);    loginBtn = (Button)findViewById(R.id.btn_login);    loginBtn.setOnClickListener(new OnClickListener() {             @Override      public void onClick(View v) {        // TODO Auto-generated method stub        if(matchLoginMsg())        {          // 如果校验成功           Intent msgIntent = new Intent(MainActivity.this, ConnectService.class);           msgIntent.putExtra(username, et_username.getText().toString().trim());           msgIntent.putExtra(password, et_password.getText().toString().trim());           startService(msgIntent);        }               }    });  }     protected boolean matchLoginMsg() {    // TODO Auto-generated method stub    userName = et_username.getText().toString().trim();    passWord = et_password.getText().toString().trim();    if(userName.equals())    {      Toast.makeText(MainActivity.this, 账号不能为空,Toast.LENGTH_SHORT).show();      return false;    }    if(passWord.equals())    {      Toast.makeText(MainActivity.this, 密码不能为空,Toast.LENGTH_SHORT).show();      return false;    }    return true;  }  //接收广播类    public class MessageReceiver extends BroadcastReceiver {      @Override      public void onReceive(Context context, Intent intent) {        String message = intent.getStringExtra(result);        Log.i(MessageReceiver, message);     // 如果登录成功       if (message.equals(true)){         // 启动Main Activity         Intent nextIntent = new Intent(MainActivity.this, NaviActivity.class);         startActivity(nextIntent);         // 结束该Activity         finish();         //注销广播接收器         context.unregisterReceiver(this);       }else{         Toast.makeText(MainActivity.this, 用户名或密码错误,请重新输入!,Toast.LENGTH_SHORT).show();      }             }    }    @Override  public boolean onCreateOptionsMenu(Menu menu) {    // Inflate the menu; this adds items to the action bar if it is present.    getMenuInflater().inflate(R.menu.main, menu);    return true;  } }

以上就是本文的全部内容,希望对大家的学习有所帮助。

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