转自:http://www.cnblogs.com/liqw/p/4266209.html
目前手机端和服务端数据交流格式一般是json,而谷歌提供了Gson来解析json。下载Gson:https://code.google.com/p/google-gson/
下载的放在lib并导入,若出现错误:java.lang.NoClassDefFoundError: com.google.gson.Gson
是因为没有导入android-support-v4.jar,导入即可。
一、单个对象生成json
生成以下类,该怎么生成呢?
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{ "createDate" : "2015-02-01 10:39:50" , "id" : "1" , "name" : "传说之美" , "password" : "123456" } |
先定义一个account类,属性有id、name、password、createDate。
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public class Account { private String id; private String password; private String name; private String createDate; public Account() { super (); } public Account(String id, String password, String name, String createDate) { super (); this .id = id; this .password = password; this .name = name; this .createDate = createDate; } public String getId() { return id; } public void setId(String id) { this .id = id; } public String getPassword() { return password; } public void setPassword(String password) { this .password = password; } public String getName() { return name; } public void setName(String name) { this .name = name; } public String getCreateDate() { return createDate; } public void setCreateDate(String createDate) { this .createDate = createDate; } @Override public String toString() { return "Account [id=" + id + ", password=" + password + ", name=" + name + ", createDate=" + createDate + "]
" ; } } |
定义好这个类,就可以利用Gson生成json字符串了。
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// 生成account对象 SimpleDateFormat sdf = new SimpleDateFormat( "yyyy-MM-dd hh:mm:ss" ); Account account = new Account( "1" , "123456" , "传说之美" , sdf.format( new Date())); // 利用gson对象生成json字符串 Gson gson = new Gson(); String jsonString = gson.toJson(account); Log.i( "" , jsonString); |
输入的log如下
二、解析json字符串为单个对象
在上面已生成了jsonString,那如何将其解析为单个对象,很简单。
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// 利用gson解析json字符串为单个对象 Account account1 = gson.fromJson(jsonString, Account. class ); Log.i( "" , account1.toString()); |
看看输出的log
三、生成单个对象的json数组
什么事json数组,类似下面的
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[ { "id" : "2" , "createDate" : "2015-02-01 11:21:27" , "password" : "123456" , "name" : "传说" }, { "id" : "2" , "createDate" : "2015-02-01 11:21:27" , "password" : "123456" , "name" : "之美" } ] |
生成json数组代码如下
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Account account2 = new Account( "2" , "123456" , "传说" , sdf.format( new Date())); Account account3 = new Account( "2" , "123456" , "之美" , sdf.format( new Date())); List<Account> accountList = new ArrayList<Account>(); accountList.add(account2); accountList.add(account3); JSONArray accountArray = new JSONArray(); for ( int i = 0 ; i < accountList.size(); i++) { String accountStr = gson.toJson(accountList.get(i)); JSONObject accountObject; try { accountObject = new JSONObject(accountStr); accountArray.put(i, accountObject); } catch (JSONException e) { e.printStackTrace(); } } Log.i( "" , accountArray.toString()); |
log的输出为
四、由多个单个对象的json数组解析为对个单个对象
多个单个对象组成的json数组解析如下
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// 解析json数组 List<Account> accountList2 = new ArrayList<Account>(); for ( int i= 0 ;i<accountArray.length(); i++){ JSONObject jsonObject = null ; try { jsonObject = accountArray.getJSONObject(i); } catch (JSONException e) { e.printStackTrace(); } if (jsonObject != null ){ Account tempAccount = gson.fromJson(jsonObject.toString(), Account. class ); accountList2.add(tempAccount); } } Log.i( "accountList2" , accountList2.toString()); |
输出的log
或者用更快捷的转化方法
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Account[] accountArrays = new Gson().fromJson(accountArray.toString(), Account[]. class ); for ( int i= 0 ;i<accountArrays.length;i++){ Log.i( "accountArrays" ,accountArrays[i].toString()); } // 转化为List List<Account> foosList = Arrays.asList(accountArrays); |
更快捷地解析成List
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// 更快捷地解析成List Type listType = new TypeToken<ArrayList<Account>>(){}.getType(); ArrayList<Account> accsList = new Gson().fromJson(accountArray.toString(), listType); Log.i( "accsList" ,accsList.toString()); |
五、生成一个对象嵌套对象的json
嵌套的json类似如下
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{ "member" : { "id" : "4" , "name" : "我是传说" }, "id" : "4" , "createDate" : "2015-02-02 12:03:32" , "password" : "888888" , "name" : "传说之美" } |
生成这个json有2种方法。
1、再添加一个member类,像添加account类一样添加即可。
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public class Member { private String id; private String name; public Member() { super (); } public Member(String id, String name) { super (); this .id = id; this .name = name; } public String getId() { return id; } public void setId(String id) { this .id = id; } public String getName() { return name; } public void setName(String name) { this .name = name; } @Override public String toString() { return "Member [id=" + id + ", name=" + name + "]
" ; } } |
生成代码如下
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// 生成对象嵌套对象的json Account account4 = new Account( "4" , "888888" , "传说之美" , sdf.format( new Date())); Member member = new Member( "4" , "我是传说" ); String accountStr = gson.toJson(account4); String memberStr = gson.toJson(member); JSONObject object = null ; try { JSONObject memberObject = new JSONObject(memberStr); object = new JSONObject(accountStr); object.put( "member" , memberObject); } catch (JSONException e) { e.printStackTrace(); } Log.i( "" , object.toString()); |
输出的log
六、解析对象嵌套对象的json
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Account account5 = gson.fromJson(object.toString(), Account. class ); Log.i( "解析对象嵌套对象的json" , account5.toString()); // 这里用isNull来判断是否存在这个object,存在就拿出member的JSONObject JSONObject memberObject = null ; if (!object.isNull( "member" )){ try { memberObject = object.getJSONObject( "member" ); } catch (JSONException e) { e.printStackTrace(); } } Member member5 = null ; if ( null != memberObject){ member5 = gson.fromJson(memberObject.toString(), Member. class ); Log.i( "解析对象嵌套对象的json" , member5.toString()); } |
输出的结果
7、另外一种解析对象嵌套对象的json
定义一个类
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public class AccountObject { private String id; private String password; private String name; private String createDate; private MemberObject memberObject = new MemberObject(); public class MemberObject { private String id; private String name; @Override public String toString() { return "MemberObject [id=" + id + ", name=" + name+ "]
" ; } } @Override public String toString() { return "AccountObject [id=" + id + ", password=" + password + ", name=" + name + ", createDate=" + createDate + "," + memberObject.toString() + "]
" ; } } |
生成json并解析
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try { JSONObject mObject = new JSONObject(memberStr); object = new JSONObject(accountStr); object.put( "memberObject" , mObject); } catch (JSONException e) { e.printStackTrace(); } AccountObject accountObject = gson.fromJson(object.toString(), AccountObject. class ); Log.i( "accountObject" , accountObject.toString()); |
打印出来的log
本文博客原创地址:http://www.cnblogs.com/liqw/p/4266209.html
demo下载链接:http://files.cnblogs.com/files/liqw/LauncherActivity.zip