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?
class="brush:java;gutter:true;">{ "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。
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 + "]\n\n"; } }
定义好这个类,就可以利用Gson生成json字符串了。
// 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。
// 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
[ { "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
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
// 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
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
// 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
{ "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。
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 + "]\n\n"; } }
生成代码如下
// 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
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
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+ "]\n\n"; } } @Override public String toString() { return "AccountObject [id=" + id + ", password=" + password + ", name=" + name + ", createDate=" + createDate + ","+ memberObject.toString() + "]\n\n"; } }
生成json并解析
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