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Android网络(3):HttpClient作客户端,Tomcat Servlet作服务器的交互示例
编辑:admin 发布时间:2019-01-26

前面相继介绍了Android网络编程里的Socket传输图片、HttpURLConnection,今天看HttpClient.

第一部分:JavaEE版的Eclipse配置Tomcat

【备注:开发后台服务器用Eclipse的JavaEE版最好的,但单就Tomcat来说(不写jsp之类的),本文下面的服务器方面操作在普通版的Eclipse也是可以的。我这里为了和ADT-bundle分开,特意重新安个JavaEE版的Eclipse。】

1、下载Eclipse的Tomcat插件:http://www.eclipsetotale.com/tomcatPlugin.html 将其解压得到com.sysdeo.eclipse.tomcat_3.3.0文件夹。将它复制到eclipse的plugins文件夹下。 重启Eclipse会看到上面有三个小猫,哈哈


2、下载apache-tomcat-7.0.53-windows-x86 最新到8.0了,但Eclipse支持貌似最高7.0,所以还是用7.0。解压apache-tomcat-7.0.53-windows-x86至C盘根目录,配置环境变量,新增CATALINA_HOME 路径为:C:\apache-tomcat-7.0.53 或者直接将这个变量配置到Path里都ok。 然后双击bin目录下的startup脚本,浏览器输入:http://localhost:8080/ 看到小猫表示windows上的tomcat配好了。

3、新建一个java工程,在里面选择Tomcat Project工程如图所示:


配置Tomcat和Server选项:




备注:新建工程这块也可以在Web里选择新建Dynamic Web Project,这是标准的使用Servlet、JSP等技术开发动态网站的项目,需要JavaEE版的Eclipse。



第二部分:联通浏览器和Tomcat

即在浏览器输入一个网址,tomcat里返回一句话,浏览器收到并显示。之所以弄这一步一是为了测试,二是后来会发现,Android里的HttpClient就跟这个浏览器一样。

1.在WEB-INF/src文件夹下新建包名org.yanzi.testtomcat,在里面新建一个类TestTomcat继承自HttpServlet.并重写里面的doGet方法。

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
resp.setContentType("text/html;charset=utf-8");
req.setCharacterEncoding("utf-8");
resp.setCharacterEncoding("utf-8");


PrintWriter out = resp.getWriter();
// //用HTML格式给浏览器返回数据
// out.println("");
// out.println("");
// out.println("Hello,Servlet!");
// out.println("");
// out.println("");
// out.println("Hello,First Servlet!");
// out.println("");
// out.println("");
out.println("Hello,第一个Tomcat!!!");
out.close();
}

2.在WEB-INF文件夹下新建文件wem.xml,内容如下:







test_yan

org.yanzi.testtomcat.TestTomcat



test_yan
/login





关于上面的配置注意:a. servlet-name是servlet的名字,这个名字可以随便起。只要servlet-name标签里名字一样就可以了。b. servlet-class里写包名+类名。c. url-pattern这里也是随便写的,是输入浏览器里的地址。本博文中浏览器的地址是:

http://localhost:8080/TestTomcat/login 这里的8080是端口,是在tomcat安装文件里的conf里的server.xml配置好的,用默认的就ok。除非此端口已被其他占用。 TestTomcat这里指的是工程的名字,而非类的名字。最后的“/login”跟web.xml里对应,注意后面不要再多加一个斜杠成这样"/login/", 这是解析不了的。

3. 修改conf文件夹下的tomcat-users.xml文件,在里面添加一个用户:



默认的都是全被注释掉的。

然后就可以点击eclipse上的小猫头像,开启这个servlet服务了。浏览器输入http://localhost:8080/TestTomcat/login 可以看到:

vcrks/ajrLy0o7o8L3A+PHA+CUBPdmVycmlkZTxiciAvPglwcm90ZWN0ZWQgdm9pZCBkb0dldChIdHRwU2VydmxldFJlcXVlc3QgcmVxLCBIdHRwU2VydmxldFJlc3BvbnNlIHJlc3ApPGJyIC8+CQkJdGhyb3dzIFNlcnZsZXRFeGNlcHRpb24sIElPRXhjZXB0aW9uIHs8YnIgLz4JCS8vIFRPRE8gQXV0by1nZW5lcmF0ZWQgbWV0aG9kIHN0dWI8YnIgLz4JCXJlc3Auc2V0Q29udGVudFR5cGUo"text/html;charset=utf-8");
req.setCharacterEncoding("utf-8");
resp.setCharacterEncoding("utf-8");


PrintWriter out = resp.getWriter();
//用HTML格式给浏览器返回数据
out.println("");
out.println("");
out.println("Tomcat Servlet测试");
out.println("");
out.println("");
out.println("Hello,First Servlet!");
out.println("");
out.println("");
out.println("Hello,第一个Tomcat!!!");
out.close();
}

看到效果:


这是因为用html格式给它设置了标题名字,并打印了一句话。这里真想吐槽一下,最初我用百度浏览器倒置了两个小时都没有出来,后来在google浏览器里一输入就ok了。真心坑爹啊。另外,如果浏览器在看视频,貌似也是出不来的。大爷的,此点么深究!!

第三部分:重写TestTomcat里的doPost()和doGet()方法。

因为我准备再手机上用doPost跟Tomcat通信,传递一个用户名和密码。Tomcat判断后再返回结果。改好后的TestTomcat.java的完整文件如下:

package org.yanzi.testtomcat;

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 TestTomcat extends HttpServlet {

	private static final long serialVersionUID = 1L;
	private static final int NAME_CODE_RIGHT = 0; //
	private static final int CODE_WRONG = 1;     //
	private static final int NAME_WRONG = 2;     //

	public TestTomcat(){

	}
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		// TODO Auto-generated method stub

		if(req == null){
			return;
		}
		resp.setContentType("text/html;charset=utf-8");
		req.setCharacterEncoding("utf-8");
		resp.setCharacterEncoding("utf-8");
		PrintWriter out = resp.getWriter();
		String name = req.getParameter("NAME");
		String code = req.getParameter("CODE");

/*		//浏览器访问,没传递任何参数。用HTML格式给浏览器返回数据
		out.println("");
		out.println("");
		out.println("Tomcat Servlet测试");
		out.println("");
		out.println("");
		out.println("Hello,哥知道你是浏览器访问的.");
		out.println("");
		out.println("");
		out.println("Hello,第一个Tomcat!!!");
		out.close();*/

		//手机客户端访问
		int ret = checkSubmit(name, code);
		out.print(ret);
		out.flush();
		out.close();

	}

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		if(req == null){
			return;
		}

		resp.setContentType("text/html;charset=utf-8");
		req.setCharacterEncoding("utf-8");
		resp.setCharacterEncoding("utf-8");

		PrintWriter out = resp.getWriter();
		String name = req.getParameter("NAME");
		String code = req.getParameter("CODE");

		int ret = checkSubmit(name, code);
		out.print(ret);
		out.flush();
		out.close();
	}

	/**
	 * 判断登录名和密码
	 * @param name
	 * @param code
	 * @return
	 */
	private int checkSubmit(String name, String code){
		int ret = -2;
		if(name.equals("admin")){
			if(code.equals("123")){
				ret = NAME_CODE_RIGHT;
			}else{
				ret = CODE_WRONG;
			}
		}else{
			ret = NAME_WRONG;
		}
		return ret;
	}


}

第四步:Android客户端的开发,这里我弄两个按钮分别对应HttpPost和HttpGet两种方式跟服务器通讯。下面是个ScrollView显示服务器回传结果.效果如下所示:


AndroidManifest.xml里加权限:


activity_main.xml的内容:



    

    

    

        

MainActivity.java里的内容:

package org.yanzi.testtomecat;

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.HttpStatus;
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.conn.params.ConnManagerParams;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.conn.DefaultClientConnection;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ScrollView;
import android.widget.TextView;

public class MainActivity extends Activity {
	public static final String URL = "http://192.168.16.8:8080/TestTomcat/login";
	Button submitBtnPost = null;
	Button submitBtnGet = null;
	TextView infoTextView = null;
	EditText nameEdit = null;
	EditText codeEdit = null;
	ScrollView scrollView = null;
	boolean isPost = true; //默认采取post登录方式
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		scrollView = (ScrollView)findViewById(R.id.info_scroll_view);
		submitBtnPost = (Button)findViewById(R.id.btn_submit_post);
		submitBtnGet = (Button)findViewById(R.id.btn_submit_get);
		infoTextView = (TextView)findViewById(R.id.tv_info);
		nameEdit = (EditText)findViewById(R.id.edit_name);
		codeEdit = (EditText)findViewById(R.id.edit_code);
		submitBtnPost.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				isPost = true;
				new SubmitAsyncTask().execute(URL);
			}
		});
		submitBtnGet.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				isPost = false;
				new SubmitAsyncTask().execute(URL);
			}
		});
	}
	


	@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;
	}
	public class SubmitAsyncTask extends AsyncTask{
		String info = "";
		@Override
		protected String doInBackground(String... params) {
			// TODO Auto-generated method stub
			String url = params[0];
			String reps = "";
			if(isPost){
				info = "HttpPost返回结果: ";
				reps = doPost(url);
			}else{
				info = "HttpGet返回结果: ";
				reps = doGet(url);	
			}
			return reps;
		}

		@Override
		protected void onPostExecute(String result) {
			// TODO Auto-generated method stub
			infoTextView.append("
" + info + result +"
");
			String res = result.trim();
			if(res.equals("0")){
				info = "验证通过.....";
			}else if(res.equals("1")){
				info = "密码错误.....";
			}else if(res.equals("2")){
				info = "用户名错误.....";
			}else if(res.equals("-1")){
				info = "返回结果异常!";
			}
			infoTextView.append(info + "
");
			scrollView.fullScroll(ScrollView.FOCUS_DOWN);
			super.onPostExecute(result);
		}
		


	}
	private String doGet(String url){
		String responseStr = "";
		try {
			String name = nameEdit.getText().toString().trim();
			String code = codeEdit.getText().toString().trim();
			String getUrl = URL + "?NAME=" + name+"&"+"CODE=" + code;		
			
			HttpGet httpRequest = new HttpGet(getUrl);
			HttpParams params = new BasicHttpParams();
			ConnManagerParams.setTimeout(params, 1000);
			HttpConnectionParams.setConnectionTimeout(params, 3000);
			HttpConnectionParams.setSoTimeout(params, 5000);
			httpRequest.setParams(params);

			HttpResponse httpResponse = new DefaultHttpClient().execute(httpRequest);
		final int ret = httpResponse.getStatusLine().getStatusCode();
		if(ret == HttpStatus.SC_OK){
			responseStr = EntityUtils.toString(httpResponse.getEntity(), HTTP.UTF_8);
		}else{
			responseStr = "-1";
		}
		} catch (ClientProtocolException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return responseStr;
	}
	
	/**
	 * 用Post方式跟服务器传递数据
	 * @param url
	 * @return
	 */
	private String doPost(String url){
		String responseStr = "";
		try {
			HttpPost httpRequest = new HttpPost(url);
			HttpParams params = new BasicHttpParams();
			ConnManagerParams.setTimeout(params, 1000); //从连接池中获取连接的超时时间
			HttpConnectionParams.setConnectionTimeout(params, 3000);//通过网络与服务器建立连接的超时时间
			HttpConnectionParams.setSoTimeout(params, 5000);//读响应数据的超时时间
			httpRequest.setParams(params);
			//下面开始跟服务器传递数据,使用BasicNameValuePair
			List paramsList = new ArrayList();
			String name = nameEdit.getText().toString().trim();
			String code = codeEdit.getText().toString().trim();
			paramsList.add(new BasicNameValuePair("NAME", name));
			paramsList.add(new BasicNameValuePair("CODE", code));
			UrlEncodedFormEntity mUrlEncodeFormEntity = new UrlEncodedFormEntity(paramsList, HTTP.UTF_8);
			httpRequest.setEntity(mUrlEncodeFormEntity);
			HttpClient httpClient = new DefaultHttpClient();
			HttpResponse httpResponse = httpClient.execute(httpRequest);
			final int ret = httpResponse.getStatusLine().getStatusCode();
			if(ret == HttpStatus.SC_OK){
				responseStr = EntityUtils.toString(httpResponse.getEntity(), HTTP.UTF_8);
			}else{
				responseStr = "-1";
			}

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

		return responseStr;
	}

}

要点注释:

1、核心在doGet()和doPost()两个函数里,可以看到用get方式比用post传递参数更方便,可以直接写到url里。使用get方式时传递数据在url里写的:

String name = nameEdit.getText().toString().trim();
String code = codeEdit.getText().toString().trim();
String getUrl = URL + "?NAME=" + name+"&"+"CODE=" + code;

post方式时是用BasicNameValuePair来弄的。其他流程都差不多。首先new一个HttpGet或HttpPost,然后设参数,共设三个,作用注释里有。然后设参数,传数据,通过HttpResponse httpResponse = httpClient.execute(httpRequest);得到返回结果。

2、如果在Tomcat里使用的是out.println(),则再解析数据时需要再得到的String上trim()一下,否则会错。

3、Android客户端URL地址为:

public static final String URL = "http://192.168.16.8:8080/TestTomcat/login";

这里的IP就是电脑的IP加端口号就ok。


当然这仅是个最基本的示例,遗留问题:

1.JSON传递数据

2.每次链接都开一个DefaultHttpClient很不科学。


参考:

http://blog.chinaunix.net/uid-25799257-id-3774015.html

http://blog.chinaunix.net/uid-25799257-id-3774047.html


http://www.bkjia.com/Androidjc/764815.htmlwww.bkjia.comtruehttp://www.bkjia.com/Androidjc/764815.htmlTechArticle前面相继介绍了Android网络编程里的Socket传输图片、HttpURLConnection,今天看HttpClient. 第一部分:JavaEE版的Eclipse配置Tomcat 【备注:开发后台服务器...

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