首先,服务器端已经存在一个项目,该项目基于SSH,已经部署在tomcat上并且正在运行了.我在这个项目的action层新建了一个包,该包主要是Struts2的一些action,只是这些action不是返回某些view,而是返回json,定义这些action的XML配置如下:

<package name="mobie" namespace="/mobie" extends="json-default"><action name="login" class="loginAction" method="login"><!-- 设置返回类型为json --><result name="success" type="json"><!-- 将对象放进一个map里面,这个map作为该action的一个field,必须具有setter个getter方法这样就可以向客户端返回整个实体的json对象,这个在需要返回复杂的组和对象是比较实用 --><param name="root">dataMap</param></result></action></package>

action类:

import java.util.HashMap;
import java.util.Map;import com.jeanselam.intf.UserService;
import com.jeanselam.pojo.User;
import com.opensymphony.xwork2.ActionSupport;public class LoginAction extends ActionSupport{private static final long serialVersionUID = 1L;private String email;private String password;private User user;private Map<String, Object> dataMap = new HashMap<String, Object>();private UserService userService;//业务接口,不写出来,省略public Map<String, Object> getDataMap() {return dataMap;}public void setDataMap(Map<String, Object> dataMap) {this.dataMap = dataMap;}public String getEmail() {return email;}public void setEmail(String email) {this.email = email;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public User getUser() {return user;}public void setUser(User user) {this.user = user;}public UserService getUserService() {return userService;}public void setUserService(UserService userService) {this.userService = userService;}public String login() throws Exception{//System.out.println("---------------------------移动端登陆");System.out.println("---------------------------移动端登陆"+email+"\t"+password);user = userService.login(email, password);dataMap.put("user", user);if(user != null){return SUCCESS;}return ERROR;}}

然后,在服务器端和android端都应该有相同的一个实体类,并且解析的json的字段名必须和该类的field名一致:

import java.util.Set;/*** Created by lin on 15-11-8.**/
public class User{private Integer id;private String email;private String password;private Integer gender;private String tel;private String nickname;private Integer isActive;//是否处于激活状态：1 是    0 否private Address address;private Set<Order> orders;//一对多public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getEmail() {return email;}public void setEmail(String email) {this.email = email;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public Integer getGender() {return gender;}public void setGender(Integer gender) {this.gender = gender;}public String getTel() {return tel;}public void setTel(String tel) {this.tel = tel;}public String getNickname() {return nickname;}public void setNickname(String nickname) {this.nickname = nickname;}public Integer getIsActive() {return isActive;}public void setIsActive(Integer isActive) {this.isActive = isActive;}public Address getAddress() {return address;}public void setAddress(Address address) {this.address = address;}public Set<Order> getOrders() {return orders;}public void setOrders(Set<Order> orders) {this.orders = orders;}@Overridepublic String toString() {return "User{" +"id=" + id +", email='" + email + '\'' +", password='" + password + '\'' +", gender=" + gender +", tel='" + tel + '\'' +", nickname='" + nickname + '\'' +", isActive=" + isActive +", address=" + address +", orders=" + orders +'}';}
}

然后主要开发android端,在android端我的思路大概是这样的:通过http协议访问服务器端的action,服务器返回json,然后android接受json后,通过解析json构造出实例,然后显示在activity上反馈给用户.于是,在android端的主要工作就是解析json和显示数据的问题了,而解析json的工作可以通过某些包来做比较方便.

新建android项目:导入一下jar包:

界面文件:

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:paddingLeft="@dimen/activity_horizontal_margin"android:paddingRight="@dimen/activity_horizontal_margin"android:paddingTop="@dimen/activity_vertical_margin"android:paddingBottom="@dimen/activity_vertical_margin"tools:context="com.ddd3.ddd3.MainActivity"android:orientation="vertical"android:background="@color/colorBackground"><TextViewandroid:layout_width="fill_parent"android:layout_height="wrap_content"android:text="JeanseLam™"android:textSize="35dp"android:textColor="@color/colorText"/><Viewandroid:layout_width="match_parent"android:layout_height="1dip"android:background="#696969"android:layout_marginTop="5dp"android:layout_marginBottom="5dp"/><TextViewandroid:layout_width="fill_parent"android:layout_height="wrap_content"android:text="@string/mainUrl"android:textSize="20dp"android:textColor="@color/colorText"/><Viewandroid:layout_width="fill_parent"android:layout_height="40dp"></View><TextViewandroid:id="@+id/loginInfo"android:layout_width="fill_parent"android:layout_height="wrap_content"android:textSize="15dp"android:textColor="@color/colorError"/><EditTextandroid:id="@+id/email"android:layout_width="fill_parent"android:layout_height="wrap_content"android:layout_marginBottom="10dp"android:hint="Type your Email"/><EditTextandroid:id="@+id/password"android:layout_width="fill_parent"android:layout_height="wrap_content"android:layout_marginBottom="10dp"android:password="true"android:hint="Enter password"/><Buttonandroid:id="@+id/btn_login"android:layout_width="fill_parent"android:layout_height="wrap_content"android:background="@drawable/button_selector"android:text="登录"android:textColor="@color/colorBtnText"android:layout_marginBottom="10dp"/><Buttonandroid:id="@+id/btn_exit"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="退出"android:background="@drawable/button_selector"android:textColor="@color/colorBtnText"android:layout_marginBottom="10dp"/><TextViewandroid:id="@+id/btn_register"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="新用户?"android:textColor="@color/colorText"android:autoLink="all"/></LinearLayout>

activity:

package com.ddd3.ddd3;import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;import com.android.volley.DefaultRetryPolicy;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import com.ddd3.entity.User;
import com.ddd3.service.JSONService;public class MainActivity extends AppCompatActivity {private EditText emailText;private EditText passwordText;private Button btn_login;private Button btn_exit;private TextView info;private RequestQueue requestQueue;//用于网络网络请求,每一个activity只需要一个requestQueue//private UserService userService;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initView();}private void initView(){emailText = (EditText)findViewById(R.id.email);passwordText = (EditText)findViewById(R.id.password);btn_login = (Button)findViewById(R.id.btn_login);btn_exit = (Button)findViewById(R.id.btn_exit);info = (TextView)findViewById(R.id.loginInfo);btn_login.setOnClickListener(new ButtonListener());btn_exit.setOnClickListener(new ButtonListener());requestQueue = Volley.newRequestQueue(this);//实例化请求队列}class ButtonListener implements View.OnClickListener{@Overridepublic void onClick(View v) {if(v.getId() == btn_login.getId()){String email = emailText.getText().toString();String password = passwordText.getText().toString();if(email.equals("") || password.equals("")){info.setText("请输入您的Email和密码");}else{//服务端url
String url = "http://192.168.56.1:8080/JeanseLam/mobie/login?email="+email+"&password="+password;JsonObjectRequest jr = new JsonObjectRequest(Request.Method.GET,url, null, new Response.Listener<org.json.JSONObject>() {@Overridepublic void onResponse(org.json.JSONObject jsonObject) {//System.out.println("----------------"+jsonObject.toString());String jsonStr = jsonObject.toString();//由于服务器端传过来的date格式gson默认是无法解析的,所以在创建gson的时候就要对date的格式进行设置Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd'T'HH:mm:ss").create();//在服务器端传过来的json是包含类名的,应该做些字符串的处理,把类名去掉才可解析成实体类,否则解析的类的所有属性值均为null,我实验过了User user = gson.fromJson(jsonStr.substring(jsonStr.indexOf(":")+1,jsonStr.length()-1), new TypeToken<User>() {}.getType());//构造实例//System.out.println("-------------------"+user.toString());application.getSession().put("user", user);//用户登陆信息作为全局变量Intent intent = new Intent(MainActivity.this,IndexActivity.class);//转到主页startActivity(intent);}
}, new Response.ErrorListener() {@Overridepublic void onErrorResponse(VolleyError error) {System.out.println("-------------------"+error.getMessage());}
});
jr.setRetryPolicy(new DefaultRetryPolicy(20 * 1000, 1, 1.0f));
requestQueue.add(jr);}}else if(v.getId() == btn_exit.getId()){android.os.Process.killProcess(android.os.Process.myPid());}}}
}

需要注意的是:由于访问本地项目,url的地址为:192.168.56.1:8080而不是localhost或其他