皮皮蝦的倔強(qiáng)

于 2022-05-23 13:25:09 發(fā)布

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文章標(biāo)簽： java json 開發(fā)語言

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一、準(zhǔn)備工作

定義三個(gè)json字符串用于以下測(cè)試：

//json字符串-簡(jiǎn)單對(duì)象

String jsonStr = "{\"studentName\":\"張三\",\"studentAge\":18}";

//json字符串-數(shù)組類型

String  jsonArrStr = "[{\"studentName\":\"張三\",\"studentAge\":18},{\"studentName\":\"李四\",\"studentAge\":17}]";

//json字符串-復(fù)雜對(duì)象

String  complexJsonStr= "{\"teacherName\":\"李尋歡\",\"teacherAge\":30,\"course\":{\"courseName\":\"武術(shù)\",\"code\":110},

                     \"students\":[{\"studentName\":\"張三\",\"studentAge\":18},{\"studentName\":\"李四\",\"studentAge\":19}]}";

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二、json字符串、json對(duì)象、java對(duì)象的轉(zhuǎn)換方法

1.JSON字符串到JSON對(duì)象的轉(zhuǎn)換

（1）json字符串-簡(jiǎn)單對(duì)象與JSONObject之間的轉(zhuǎn)換

JSONObject jsonObj = JSON.parseObject(jsonStr);

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（2）json字符串-數(shù)組類型與JSONArray之間的轉(zhuǎn)換

JSONArray jsonArray = JSON.parseArray(jsonArrStr);

//遍歷JSONArray方法1

for(int i = 0; i < jsonArray.size(); i++){

   JSONObject jsonObj = jsonArray.getJSONObject(i); 

}

//遍歷JSONArray方法2

for(Object obj : jsonArray){

    JSONObject jsonObject = (JSONObject) obj;

}

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（3）json字符串-復(fù)雜對(duì)象與JSONObject之間的轉(zhuǎn)換

JSONObject jsonObj = JSON.parseObject(complexJsonStr);

//取出復(fù)雜對(duì)象中各項(xiàng)內(nèi)容

String teacherName = jsonObj.getString("teacherName");

Integer teacherAge = jsonObj.getInteger("teacherAge");

JSONObject course = jsonObj.getJSONObject("course");

JSONArray students = jsonObj.getJSONArray("students");

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2.JSON對(duì)象到JSON字符串的轉(zhuǎn)換

JSONObject jsonObj = new JSONObject();

//JSONObject到JSON字符串的轉(zhuǎn)換

String jsonStr = jsonObj.toJSONString();

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3.JSON字符串到Java對(duì)象的轉(zhuǎn)換

JSON字符串與JavaBean之間的轉(zhuǎn)換建議使用TypeReference類

（1）json字符串-簡(jiǎn)單對(duì)象與Java對(duì)象之間的轉(zhuǎn)換

// 方法1

Student student = JSON.parseObject(jsonStr , new TypeReference() {});

// 方法2

Student student = JSON.parseObject(jsonStr , Student.class);

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（2）json字符串-數(shù)組與Java對(duì)象之間的轉(zhuǎn)換

ArrayListstudents = JSON.parseObject(jsonArrStr, new TypeReference() {});

for (Student student : students) {

   System.out.println(student.getStudentName()+":"+student.getStudentAge());

}

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（3）json字符串-復(fù)雜對(duì)象與Java對(duì)象之間的轉(zhuǎn)換

Teacher teacher = JSON.parseObject(complexJsonStr, new TypeReference() {});

//獲取teacher中的內(nèi)容

String teacherName = teacher.getTeacherName();

Integer teacherAge = teacher.getTeacherAge();

Course course = teacher.getCourse();

Liststudents = teacher.getStudents();

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4.Java對(duì)象到JSON字符串的轉(zhuǎn)換

Teacher teacher = new Teacher();

String jsonStr = JSON.toJSONString(teacher);

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5.Java對(duì)象到JSON對(duì)象的轉(zhuǎn)換

String jsonStr= JSON.toJSONString(student);

JSONObject jsonObj = JSON.parseObject(jsonStr);

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6.JSON對(duì)象到Java對(duì)象的轉(zhuǎn)換

# 方法1，先轉(zhuǎn)換為json字符串，再使用parseObject

String jsonStr = jsonObj.toJSONString();

Student stu = JSON.parseObject(jsonStr,new TypeReference() {});

# 方法2，直接使用toJavaObject

Student stu = JSON.toJavaObject(jsonObj, Student.class);

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例子

1.json字符串轉(zhuǎn)化為java實(shí)體類 (parseObject)

ApprovalVo approvalVo = JSON.parseObject(str, ApprovalVo.class);

// str == json字符串

// ApprovalVo == 實(shí)體類

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2.json字符串轉(zhuǎn)化為list對(duì)象 (parseArray)

String str2 = "[{'password':'123123','username':'zhangsan'},{'password':'321321','username':'lisi'}]";

Listusers = JSON.parseArray(jsonStr2, User.class);

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3.json字符串轉(zhuǎn)化為復(fù)雜java對(duì)象 （parseObject）

//  復(fù)雜對(duì)象->>>>對(duì)象中嵌套對(duì)象的

String str3 = "{'name':'userGroup','users':[{'password':'123123','username':'zhangsan'},{'password':'321321','username':'lisi'}]}";

UserGroup userGroup = JSON.parseObject(jsonStr3, UserGroup.class);

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把實(shí)體類轉(zhuǎn)化成json字符串

String str = JSON.toJSONString(ApprovalVo);

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把json字符串轉(zhuǎn)化成JSONObject

 String jsonStr = "{\"school\":\"商職\",\"sex\":\"男\(zhòng)",\"name\":\"wjw\",\"age\":22}";

 JSONObject jsonObject = JSONObject.parseObject(jsonStr);

 System.out.println(jsonObject.getString("name"));

 System.out.println(jsonObject.getInteger("age"));

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參考：

https://zhuanlan.zhihu.com/p/476747417

https://blog.51cto.com/u_15281317/3008066

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版權(quán)聲明：本文為CSDN博主「皮皮蝦的倔強(qiáng)」的原創(chuàng)文章，遵循CC 4.0 BY-SA版權(quán)協(xié)議，轉(zhuǎn)載請(qǐng)附上原文出處鏈接及本聲明。

原文鏈接：https://blog.csdn.net/Wolves_howl/article/details/124921713