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Android网络(3):HttpClient作客户端,Tomcat Servlet作服务器的交互示例
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("<html>");
// out.println("<head>");
// out.println("<title>Hello,Servlet!</title>");
// out.println("</head>");
// out.println("<body>");
// out.println("Hello,First Servlet!");
// out.println("</body>");
// out.println("</html>");
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:
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app >
<servlet>
<servlet-name>test_yan</servlet-name>
<!-- 名字随便 -->
<servlet-class>org.yanzi.testtomcat.TestTomcat</servlet-class>
<!-- servlet类名 -->
</servlet>
<servlet-mapping>
<servlet-name>test_yan</servlet-name>
<url-pattern>/login</url-pattern>
<!-- url访问虚拟路径,最后我们就是通过工程名/login进行访问的,像这样http://127.0.0.1:8000/LoginAction/login -->
</servlet-mapping>
</web-app>
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:
<role rolename="manager"/>
<user username="admin" password="admin" roles="manager"/>
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:
在doGet()函数里用html格式输出,即:
@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("<html>");
out.println("<head>");
out.println("<title>Tomcat Servlet测试</title>");
out.println("</head>");
out.println("<body>");
out.println("Hello,First Servlet!");
out.println("</body>");
out.println("</html>");
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("<html>"); out.println("<head>"); out.println("<title>Tomcat Servlet测试</title>"); out.println("</head>"); out.println("<body>"); out.println("Hello,哥知道你是浏览器访问的."); out.println("</body>"); out.println("</html>"); 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: <uses-permission android:name="android.permission.INTERNET"/>
activity_main.xml的内容:
<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" > <EditText android:id="@+id/edit_name" android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="输入用户名" /> <EditText android:id="@+id/edit_code" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_below="@id/edit_name" android:hint="输入密码" /> <LinearLayout android:id="@+id/layout_btn" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_centerInParent="true" android:orientation="horizontal" > <Button android:id="@+id/btn_submit_post" android:layout_width="0dip" android:layout_height="wrap_content" android:layout_weight="1" android:gravity="center" android:text="POST登录 " /> <Button android:id="@+id/btn_submit_get" android:layout_width="0dip" android:layout_height="wrap_content" android:layout_weight="1" android:gravity="center" android:text="GET登录 " /> </LinearLayout> <ScrollView android:id="@+id/info_scroll_view" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_below="@id/layout_btn" > <TextView android:id="@+id/tv_info" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="结果显示........." /> </ScrollView> </RelativeLayout>
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, Void, String>{ 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("\n" + info + result +"\n"); 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 + "\n"); 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<BasicNameValuePair> paramsList = new ArrayList<BasicNameValuePair>(); 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