Android 利用Gson生成或解析json

2019-11-09 18:45:07

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一、单个对象生成json

生成以下类，该怎么生成呢？ { "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); 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()); 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()); 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()); 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ListList<Account> foosList = Arrays.asList(accountArrays);更快捷地解析成List // 更快捷地解析成ListType 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jsonAccount 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()); 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JSONObjectJSONObject 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());} 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());

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