本文介绍了如何使用Android搭建客户端，实现手机和服务器的交互。让我们了解如何采用SSH框架，把服务器端的信息用JSON的形式发送到手机端。
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笔者以前是学的Java EE，由于项目需要要开发Android，所以临时补了一个多星期，主要是手机端和服务器端交互，双向开发的。
首先在服务器端，我采用的是SSH框架，struts 2集合了JSON插件，服务器和客户端的信息交互采用的JSON来传输，由于在服务器端用了Struts 2，所以我就用装了一个JSON插件。这样，很轻易的就把服务器端的信息用JSON的形式发送到了手机端。以下是代码：
首先，在服务器端搭建好SSH框架，具体细节就不在陈述。struts.xml配置如下：
1. <packagename="login"extends="json-default">
2. <actionname="login"class="com.jclick.test.LoginAction"method="login">
3. <resulttype="json"><paramname="includeProperties">result</param></result>
4. </action>
5. </package>
6.
7. <packagename="login"extends="json-default">
8. <actionname="login"class="com.jclick.test.LoginAction"method="login">
9. <resulttype="json"><paramname="includeProperties">result</param></result>
10. </action>
11. </package>手机端的代码如下：
首先，手机端有一个缓存类，主要用于缓存一些手机端需要访问的数据，这样的好处是可以达达节省手机和服务器的交互，用单例实现的：
1. packagecom.jclick.cache;
2.
3. importcom.jclick.bean.User;
4.
5. publicclassCache{
6.
7. privateUserUser;
8.
9. privateCache(){
10.
11. }
12. /**构造单例*/
13. privatestaticclassCacheHolder{
14. privatestaticfinalCacheINSTANCE=newCache();
15. }
16. publicCachegetInstance(){
17. returnCacheHolder.INSTANCE;
18. }
19. publicUsergetUser(){
20. returnUser;
21. }
22. publicvoidsetUser(UserUser){
23. this.User=User;
24. }
25.
26. }
27.
28. packagecom.jclick.cache;
29.
30. importcom.jclick.bean.User;
31.
32. publicclassCache{
33.
34. privateUserUser;
35.
36. privateCache(){
37.
38. }
39. /**构造单例*/
40. privatestaticclassCacheHolder{
41. privatestaticfinalCacheINSTANCE=newCache();
42. }
43. publicCachegetInstance(){
44. returnCacheHolder.INSTANCE;
45. }
46. publicUsergetUser(){
47. returnUser;
48. }
49. publicvoidsetUser(UserUser){
50. this.User=User;
51. }
52.
53. }接着开始书写手机端的协议，用户向服务器发送请求，同时服务器反馈给手机端信息的：
1. packagecom.jclick.protocol;
2.
3. importjava.io.BufferedReader;
4. importjava.io.InputStreamReader;
5. importjava.util.ArrayList;
6. importjava.util.List;
7.
8. importorg.apache.http.HttpResponse;
9. importorg.apache.http.NameValuePair;
10. importorg.apache.http.client.HttpClient;
11. importorg.apache.http.client.entity.UrlEncodedFormEntity;
12. importorg.apache.http.client.methods.HttpPost;
13. importorg.apache.http.impl.client.DefaultHttpClient;
14. importorg.apache.http.message.BasicNameValuePair;
15. importorg.json.JSONException;
16. importorg.json.JSONObject;
17.
18. publicclassBaseProtocol{
19. privateStringBuildersb=newStringBuilder();
20.
21. privateHttpClienthttpClient;
22. privateHttpPosthttpRequest;
23. privateHttpResponseresponse;
24.
25. privateList<NameValuePair>nameValuePair=newArrayList<NameValuePair>();
26.
27. BaseProtocol(){
28. httpClient=newDefaultHttpClient();
29. }
30.
31. /**
32. *向服务器端发送请求
33. *
34. *@paramurl
35. *@throwsException
36. */
37. protectedvoidpack(Stringurl)throwsException{
38. httpClient=newDefaultHttpClient();
39. httpRequest=newHttpPost(url);
40.
41. httpRequest.setEntity(newUrlEncodedFormEntity(nameValuePair));
42. response=httpClient.execute(httpRequest);
43. }
44.
45. /**
46. *得到返回数据
47. *
48. *@paramurl
49. *@return
50. *@throwsException
51. */
52. protectedvoidparse()throwsException{
53. //TODO状态处理500200
54. if(response.getStatusLine().getStatusCode()==200){
55.
56. BufferedReaderbufferedReader2=newBufferedReader(
57. newInputStreamReader(response.getEntity().getContent()));
58. for(Strings=bufferedReader2.readLine();s!=null;s=bufferedReader2
59. .readLine()){
60. sb.append(s);
61. }
62. }
63. }
64.
65. /**
66. *向服务器发送信息
67. *
68. *@paramkey
69. *@paramvalue
70. */
71. publicvoidaddNameValuePair(Stringkey,Stringvalue){
72. nameValuePair.add(newBasicNameValuePair(key,value));
73. }
74.
75. /**
76. *返回JSONObject对象数据模型
77. *
78. *@return
79. *@throwsJSONException
80. */
81. publicJSONObjectgetJSON()throwsJSONException{
82. returnnewJSONObject(sb.toString());
83. }
84.
85. }
86.
87. packagecom.jclick.protocol;
88.
89. importjava.io.BufferedReader;
90. importjava.io.InputStreamReader;
91. importjava.util.ArrayList;
92. importjava.util.List;
93.
94. importorg.apache.http.HttpResponse;
95. importorg.apache.http.NameValuePair;
96. importorg.apache.http.client.HttpClient;
97. importorg.apache.http.client.entity.UrlEncodedFormEntity;
98. importorg.apache.http.client.methods.HttpPost;
99. importorg.apache.http.impl.client.DefaultHttpClient;
100. importorg.apache.http.message.BasicNameValuePair;
101. importorg.json.JSONException;
102. importorg.json.JSONObject;
103.
104. publicclassBaseProtocol{
105. privateStringBuildersb=newStringBuilder();
106.
107. privateHttpClienthttpClient;
108. privateHttpPosthttpRequest;
109. privateHttpResponseresponse;
110.
111. privateList<NameValuePair>nameValuePair=newArrayList<NameValuePair>();
112.
113. BaseProtocol(){
114. httpClient=newDefaultHttpClient();
115. }
116.
117. /**
118. *向服务器端发送请求
119. *
120. *@paramurl
121. *@throwsException
122. */
123. protectedvoidpack(Stringurl)throwsException{
124. httpClient=newDefaultHttpClient();
125. httpRequest=newHttpPost(url);
126.
127. httpRequest.setEntity(newUrlEncodedFormEntity(nameValuePair));
128. response=httpClient.execute(httpRequest);
129. }
130.
131. /**
132. *得到返回数据
133. *
134. *@paramurl
135. *@return
136. *@throwsException
137. */
138. protectedvoidparse()throwsException{
139. //TODO状态处理500200
140. if(response.getStatusLine().getStatusCode()==200){
141.
142. BufferedReaderbufferedReader2=newBufferedReader(
143. newInputStreamReader(response.getEntity().getContent()));
144. for(Strings=bufferedReader2.readLine();s!=null;s=bufferedReader2
145. .readLine()){
146. sb.append(s);
147. }
148. }
149. }
150.
151. /**
152. *向服务器发送信息
153. *
154. *@paramkey
155. *@paramvalue
156. */
157. publicvoidaddNameValuePair(Stringkey,Stringvalue){
158. nameValuePair.add(newBasicNameValuePair(key,value));
159. }
160.
161. /**
162. *返回JSONObject对象数据模型
163. *
164. *@return
165. *@throwsJSONException
166. */
167. publicJSONObjectgetJSON()throwsJSONException{
168. returnnewJSONObject(sb.toString());
169. }
170.
171. }接着是登陆协议，在这里我只是模拟登陆使用的一个类，仅供大家参考：
1. packagecom.jclick.protocol;
2.
3. importorg.json.JSONObject;
4.
5. importcom.jclick.bean.User;
6.
7. publicclassLoginProtocolextendsBaseProtocol{
8.
9. privatefinalstaticStringURL="http://localhost:8080/test/login";
10.
11. publicbooleancheckLogin(Userusr){
12. try{
13. pack(URL);
14. parse();
15. JSONObjectobj=this.getJSON();
16. if(obj.getString("result").equals("failed")){
17. returnfalse;
18. }else{
19. returntrue;
20. }
21. }catch(Exceptione){
22. e.printStackTrace();
23. returnfalse;
24. }
25. }
26.
27. }
28.
29. packagecom.jclick.protocol;
30.
31. importorg.json.JSONObject;
32.
33. importcom.jclick.bean.User;
34.
35. publicclassLoginProtocolextendsBaseProtocol{
36.
37. privatefinalstaticStringURL="http://localhost:8080/test/login";
38.
39. publicbooleancheckLogin(Userusr){
40. try{
41. pack(URL);
42. parse();
43. JSONObjectobj=this.getJSON();
44. if(obj.getString("result").equals("failed")){
45. returnfalse;
46. }else{
47. returntrue;
48. }
49. }catch(Exceptione){
50. e.printStackTrace();
51. returnfalse;
52. }
53. }
54.
55. }然后是User实体类，主要用于保存用户信息：
1. packagecom.jclick.bean;
2.
3. publicclassUser{
4. privateStringusername;
5. privateStringpassword;
6. publicStringgetUsername(){
7. returnusername;
8. }
9. publicvoidsetUsername(Stringusername){
10. this.username=username;
11. }
12. publicStringgetPassword(){
13. returnpassword;
14. }
15. publicvoidsetPassword(Stringpassword){
16. this.password=password;
17. }
18.
19. }
20.
21. packagecom.jclick.bean;
22.
23. publicclassUser{
24. privateStringusername;
25. privateStringpassword;
26. publicStringgetUsername(){
27. returnusername;
28. }
29. publicvoidsetUsername(Stringusername){
30. this.username=username;
31. }
32. publicStringgetPassword(){
33. returnpassword;
34. }
35. publicvoidsetPassword(Stringpassword){
36. this.password=password;
37. }
38.
39. }最后就是LoginActivity里边判断登陆的代码了，详细代码不再贴出来了，仅贴一个判断登陆的代码：
1. privatevoidcheckedData(){
2. username=((EditText)findViewById(R.id.username)).getText().toString();
3. password=((EditText)findViewById(R.id.password)).getText().toString();
4.
5. Useruser=newUser();
6. user.setUsername(username);
7. user.setPassword(password);
8. LoginProtocollogin=newLoginProtocol();
9. booleanresult=login.checkLogin(user);
10.
11. if(result){SpiderCache.getInstance().setUserSession(user);
12. Toast.makeText(getApplicationContext(),"登录成功",1000).show();
13. Intentintent=newIntent();
14. intent.setClass(LoginActivity.this,WelcomeActivity.class);
15. startActivity(intent);
16. }else{Toast.makeText(LoginActivity.this,"密码或用户名不匹配，请重新输入！",1000).show();
17. }
18. }
19.
20. privatevoidcheckedData(){
21. username=((EditText)findViewById(R.id.username)).getText().toString();
22. password=((EditText)findViewById(R.id.password)).getText().toString();
23.
24. Useruser=newUser();
25. user.setUsername(username);
26. user.setPassword(password);
27. LoginProtocollogin=newLoginProtocol();
28. booleanresult=login.checkLogin(user);
29.
30. if(result){ SpiderCache.getInstance().setUserSession(user);
31. Toast.makeText(getApplicationContext(),"登录成功",1000).show();
32. Intentintent=newIntent();
33. intent.setClass(LoginActivity.this,WelcomeActivity.class);
34. startActivity(intent);
35. }else{ Toast.makeText(LoginActivity.this,"密码或用户名不匹配，请重新输入！",1000).show();
36. }
37. }以上代码为了跟大家分享一下，感觉手机端和服务器双向开发非常过瘾。同时对Android的兴趣大大提升，它也没有我们想象中的那么难。
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