Android 网络编程---STRUTS2,JSON，HttpClient

     在Android开发过程中，我们需要访问网络上的Web资源，比如网络上的WEB请求。在这里Android就好像是一个终端，可以用来接收Web服务器端发送过来的数据。下面我以Struts2作为Web服务器端的Web框架。来说明Android客户端接收Web请求的过程。

 

首先，我们要配置Web服务器端，添加Struts2所需要的JAR包（包括JSON包）

下面是服务器端所要配置的JAR包，如下所示：

 

 

 

我们看看json包，有如下： json-lib-**.jdk15.jar,struts2-json-plugin-***.jar,ezmorph-**.jar

 

 

接下配置web.xml文件，代码如下所示：

 

<!-- 定义Struts2的核心控制器：FilterDispatcher --> <filter> <!-- 定义核心Filter的名称 --> <filter-name>struts2</filter-name> <!-- 定义Filter的实现类 --> <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>

 

 

添加完JAR包后。我们来配置一下struts.xml文件，这个文件存放在src根目录下面，代码如下所示：

 

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE struts PUBLIC"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN""http://struts.apache.org/dtds/struts-2.0.dtd"><struts><!-- setting encoding,DynamicMethod,language<constant name="struts.custom.i18n.resources" value="messageResource"></constant>--><constant name="struts.i18n.encoding" value="UTF-8"></constant><constant name="struts.enable.DynamicMethodInvocation"value="true"></constant><!-- truts.enable.DynamicMethodInvocation = true，-动态方法调用，为true时，就可以在struts.xml配置“*”的通配符，来调用action里的方法 --><!-- add package here extends="struts-default"--><package name="dongzi" extends="json-default"><!--需要将struts-default改为json-default--><!-- setting action --><action name="login" class="com.dongzi.action.LoginAction"method="login"><result type="json"></result><!--返回值类型设置为json,不设置返回页面--></action></package></struts>

 

 

看看这个action

    <action name="login" class="com.dongzi.action.LoginAction"
            method="login">
            <result type="json"></result>
            <!--返回值类型设置为json,不设置返回页面-->
        </action>

 

返回的是json 数据。而且是由LoginAction类去处理，它存放在com.dongzi.action下面。LoginAction类的代码如下：

 

public class LoginAction extends ActionSupport implements ServletRequestAware,ServletResponseAware {/** * */private static final long serialVersionUID = 1L;HttpServletRequest request;HttpServletResponse response;public void setServletRequest(HttpServletRequest request) {this.request = request;}public void setServletResponse(HttpServletResponse response) {this.response = response;}public void login() {try {// HttpServletRequest request =ServletActionContext.getRequest();// HttpServletResponse response=ServletActionContext.getResponse();this.response.setContentType("text/html;charset=utf-8");this.response.setCharacterEncoding("UTF-8");// 将要返回的实体对象进行json处理// JSONObject json=JSONObject.fromObject(this.getUsername());// 输出格式如：{"id":1, "username":"zhangsan", "pwd":"123"}// System.out.println(json); //this.response.getWriter().write(json.toString());//{"username":"mingg","password":"123"}JSONObject json=new JSONObject();//json.put("username", "mingg");//json.put("password","123");//【这里在JSON中包含一个Map】Map map=new HashMap<Object, String>();map.put("username", "xiaomingg");map.put("password", "1234");map.put("state", "1");json.put("userbean", map);response.getWriter().write(json.toString());////{"userbean":{"username":"100196","password":"1234453","State":1}} /** * 值的数组{"people": [{"username":"mingg","password":"123","email":"[e-mail]"},{"username":"jie","password":"111","email":"[e-mail]"},{"username":"yong","password":"1232","email":"[e-mail]"}]} *///JSONArray jsonArray=new JSONArray();////JSONObject json=new JSONObject();//json.put("username", "mingg");//json.put("password","123");// json.put("email", "[e-mail]");// // JSONObject json1=new JSONObject();//json1.put("username", "jie");//json1.put("password","111");// json1.put("email", "[e-mail]");// // JSONObject json2=new JSONObject();//json2.put("username", "yong");//json2.put("password","1232");// json2.put("email", "[e-mail]");//// jsonArray.add(0, json);// jsonArray.add(1, json1);// jsonArray.add(2, json2);// // // JSONObject alObject=new JSONObject();// alObject.put("people", jsonArray); /*** *{ "programmers": [ * {"username":"mingg","password":"123","email":"[e-mail]"}, * * {"username":"jie","password":"111","email":"[e-mail]"}, * * {"username":"yong","password":"1232","email":"[e-mail]"}], * "authors": [ * {"username":"mingg","password":"123","genre":"science fiction"}, * * {"username":"jie","password":"111","genre":"fantasy"}, * * {"username":"yong","password":"1232","genre":"christian fiction"}], * "musicians": [ * {"username":"mingg","password":"123","instrument":"guitar"}, * * {"username":"jie","password":"111","instrument":"piano"}, * * {"username":"yong","password":"1232","instrument":"flute"}] * } * */ //JSONArray jsonArray=new JSONArray();////JSONObject json=new JSONObject();//json.put("username", "mingg");//json.put("password","123");// json.put("email", "[e-mail]");// // JSONObject json1=new JSONObject();//json1.put("username", "jie");//json1.put("password","111");// json1.put("email", "[e-mail]");// // JSONObject json2=new JSONObject();//json2.put("username", "yong");//json2.put("password","1232");// json2.put("email", "[e-mail]");//// jsonArray.add(0, json);// jsonArray.add(1, json1);// jsonArray.add(2, json2);// // // // JSONArray jsonArray2=new JSONArray();////JSONObject json20=new JSONObject();//json20.put("username", "mingg");//json20.put("password","123");// json20.put("genre", "science fiction");// // JSONObject json21=new JSONObject();//json21.put("username", "jie");//json21.put("password","111");// json21.put("genre", "fantasy");// // JSONObject json22=new JSONObject();//json22.put("username", "yong");//json22.put("password","1232");// json22.put("genre", "christian fiction");//// jsonArray2.add(0, json20);// jsonArray2.add(1, json21);// jsonArray2.add(2, json22);// // // JSONArray jsonArray3=new JSONArray();////JSONObject json30=new JSONObject();//json30.put("username", "mingg");//json30.put("password","123");// json30.put("instrument", "guitar");// // JSONObject json31=new JSONObject();//json31.put("username", "jie");//json31.put("password","111");// json31.put("instrument", "piano");// // JSONObject json32=new JSONObject();//json32.put("username", "yong");//json32.put("password","1232");// json32.put("instrument", "flute");//笛//// jsonArray3.add(0, json30);// jsonArray3.add(1, json31);// jsonArray3.add(2, json32);// // // JSONObject alObject=new JSONObject();// alObject.put("programmers", jsonArray);// alObject.put("authors", jsonArray2);// alObject.put("musicians", jsonArray3); /** * yong:1232:[e-mail] */ //获取任意节点的值：试例，第个节点，第三个子节点 // JSONArray jsonArrayt11 = (JSONArray) alObject.get("programmers");// // JSONObject jsonObject11=(JSONObject)jsonArrayt11.get(2);// // String username=jsonObject11.getString("username");// String password=jsonObject11.getString("password");// String email=jsonObject11.getString("email");// // StringBuffer sBuffer=new StringBuffer();// sBuffer.append(username+":").append(password+":").append(email); //response.getWriter().write(username.toString());/** * JSONObject json=new JSONObject(); json.put("login", "login"); * response.setContentType("text/html;charset=utf-8"); * System.out.println(json); byte[] jsonBytes = * json.toString().getBytes("utf-8"); * response.setContentLength(jsonBytes.length); * response.getOutputStream().write(jsonBytes); */// JSONObject json=new JSONObject(); // json.put("login", "login");// byte[] jsonBytes = json.toString().getBytes("utf-8");// response.setContentType("text/html;charset=utf-8");// response.setContentLength(jsonBytes.length);// response.getOutputStream().write(jsonBytes);// response.getOutputStream().flush();// response.getOutputStream().close();} catch (Exception e) {e.printStackTrace();}// return null;}}

 

我下面简单说一下JSON解析过程。

          JSONObject json=new JSONObject();
            //【这里在JSON中包含一个Map】
            Map map=new HashMap<Object, String>();
            map.put("username", "xiaomingg");
            map.put("password", "1234");
            map.put("state", "1");
            json.put("userbean", map);
           
            response.getWriter().write(json.toString());

 

 

   通过访问http://localhost:8888/AndroidServerApp/login.action，得到如下JSON数据：

 

 

 

服务器端的配置完成了。下面我来配置android客户端了。

由于Android内置提拱了解析JSON数据的包。所以就不需要使用第三方包了

 

Android 访问网络资源的代码如下所示：

 

private static String url = "http://10.0.2.2:8888/AndroidServerApp/login.action";getPDAServerData(url);private void getPDAServerData(String url) {HttpClient client = new DefaultHttpClient();//提拱默认的HttpClient实现HttpPost request;try {request = new HttpPost(new URI(url));HttpResponse response = client.execute(request);// 判断请求是否成功if (response.getStatusLine().getStatusCode() == 200) { //200表示请求成功HttpEntity entity = response.getEntity();if (entity != null) {String out = EntityUtils.toString(entity);JSONObject jsonObject;String username = "";String password = "";String stateStr="";UserBean userBean=new UserBean();try {//{"userbean":{"username":"100196","password":"1234453","State":1}}//JSONObject jsonObject = new JSONObject(builder.toString()).getJSONObject("userbean"); jsonObject = new JSONObject(out).getJSONObject("userbean");userBean.setUsername(jsonObject.getString("username"));userBean.setPassword( jsonObject.getString("password"));userBean.setState(Integer.parseInt(jsonObject.getString("state")));} catch (JSONException e) {// TODO Auto-generated catch blocke.printStackTrace();}new AlertDialog.Builder(this).setMessage(userBean.getUsername() + ":" + userBean.getState()).create().show();}}} catch (URISyntaxException e) {e.printStackTrace();new AlertDialog.Builder(this).setMessage(e.getMessage()).create().show();} catch (ClientProtocolException e) {e.printStackTrace();new AlertDialog.Builder(this).setMessage(e.getMessage()).create().show();} catch (IOException e) {e.printStackTrace();new AlertDialog.Builder(this).setMessage(e.getMessage()).create().show();}}

 

里面的IP地址：10.0.2.2，代表着手机模拟器本地的地址，相当于localhost,但不能使用localhost,或者127.0.0.1，因不是在PC机上测试，而是在手机AVD上测试之。

 

 

而UserBean.java,它就是一个JAVABEAN,代码如下所示：

 

package po;public class UserBean {private String username;private String password;private int state;public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public int getState() {return state;}public void setState(int state) {this.state = state;}}

 

 

 

注恴必须AndroidManifest.xml中加入如下代码，不然Android就不能访问web资源。

 

     <uses-permission android:name="android.permission.INTERNET" /> 

 

 

 

最终得到如下界面：