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原创 Android 生成json字符串

 2023-8-4 17:05  908 3 3 分类: 智能手机文集: 技术

String生成的json数据有两种

String json="[{'name':'tom','age':12},{'name':'jack','age':13}]";
JSONArray a = new JSONArray(json);
System.out.println(a.toString());

String json2="{'json':[{'name':'tom','age':14},{'name':'jack','age':15}]}";
JSONObject b= new JSONObject(json2);
System.out.println(b.toString());

String类型的数据加“”，然后每个key，value加单引号。

JsonObject生成的数据有两种

JSONArray array =new JSONArray();
JSONObject object =new JSONObject();
JSONObject object1 =new JSONObject();
JSONObject obj= new JSONObject();
try {
object.put("item1","value1");
object.put("age",12);
object.put("name","tom");
object1.put("item2","value2");
object1.put("age",12232);
object1.put("name","tom");
array.put(object);
array.put(object1);
obj.put("name",array);
System.out.println(obj.toString());
}catch (Exception e){
}
结果：{"name":[{"item1":"value1","name":"tom","age":12},{"item2":"value2","name":"tom","age":12232}]}

JSONArray array1 =new JSONArray();
JSONObject object2 =new JSONObject();
JSONObject object3 =new JSONObject();
try {
object2.put("color","red");
object2.put("height",20);
object3.put("color","blue");
object3.put("height",1010);
array1.put(object2);
array1.put(object3);
System.out.println(array1.toString());
}catch (Exception e){
}
结果：[{"color":"red","height":20},{"color":"blue","height":1010}]

将集合生成json数据

Map<String ,String> map =new HashMap<>();
Map<String ,String> map2 =new HashMap<>();
map.put("name1","tom1");
map.put("age1","12");
map2.put("name1","tom1");
map2.put("age1","12");
JSONObject object4 =new JSONObject();
JSONArray array2 =new JSONArray();
array2.put(map);
array2.put(map2);
object4.put("key",array2);
System.out.println(object4.toString());
结果：{"key":[{"name1":"tom1","age1":"12"},{"name1":"tom1","age1":"12"}]}

Map<String ,String> map1 =new HashMap<>();
map1.put("as","adasd");
map1.put("asfa","afasff");
JSONArray array3 =new JSONArray();
array3.put(map1);
System.out.println(array3.toString());
结果：[{"asfa":"afasff","as":"adasd"}]

通过Gson生成json

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);

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 accountList = new ArrayList();

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 accountList2 = new ArrayList();

for(int i=0;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

Log.i("accountArrays",accountArrays.toString());

}

// 转化为List

List foosList = Arrays.asList(accountArrays);

更快捷地解析成List

// 更快捷地解析成List

Type listType = new TypeToken>(){}.getType();

ArrayList 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());

android