com.alibaba.fastjson.JSONObject;的使用

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com.alibaba.fastjson.JSONObject;的使用

2018-11-04 23:51:23 mameng1998 阅读数 6404更多

分类专栏： java

 

1  POM.xml

1. <!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
2. <dependency>
3. <groupId>com.alibaba</groupId>
4. <artifactId>fastjson</artifactId>
5. <version>1.2.51</version>
6. </dependency>

2  附上代码例子

2.1 创建2个实体类，供后面例子使用

1. public class School {
2. private String id;
3. private String name;
4. List<User> students = new ArrayList<User>();
5. public String getId() {
6. return id;
7. }
8. public void setId(String id) {
9. this.id = id;
10. }
11. public String getName() {
12. return name;
13. }
14. public void setName(String name) {
15. this.name = name;
16. }
17. public List<User> getStudents() {
18. return students;
19. }
20. public void setStudents(List<User> students) {
21. this.students = students;
22. }
23. }

1. public class User {
2. private String id;
3. private String name;
4.  
5. public User(){
6.  
7. }
8. public User(String id, String name){
9. this.id = id;
10. this.name = name;
11. }
12.  
13. public String getId() {
14. return id;
15. }
16. public void setId(String id) {
17. this.id = id;
18. }
19. public String getName() {
20. return name;
21. }
22. public void setName(String name) {
23. this.name = name;
24. }
25. }

2.2 Json字符串与Map、List、object之间的相互转换

1. import java.util.ArrayList;
2. import java.util.HashMap;
3. import java.util.List;
4. import java.util.Map;
5.  
6. import com.alibaba.fastjson.JSON;
7. import com.alibaba.fastjson.JSONArray;
8. import com.alibaba.fastjson.JSONObject;
9.  
10. public class TestFastJson {
11.  
12. public static void main(String[] args){
13. json2JsonObject();//将Json字符串转换为JSONObject对象
14. json2JavaBean();//将Json字符串转换为JavaBean对象
15. json2JsonArray();//将Json字符串转换为JSONArray对象
16. json2JavaBeanList();//将Json字符串转换为JavaBean的集合
17. javaBean2Json();//将JavaBean转换为Json格式的数据
18. javaBean2JsonObject();//将JavaBean转换为JSONObject对象
19. json2ListInMap();//从Json字符串的Map中获取List对象
20. list2JsonInMap();//将含list的Map对象转换为Json字符串
21. stringToMap();//json字符串转map
22. mapToString();//map转json字符串
23. mapToJsonObject();//map转json对象
24. testList2String()；//list转json字符串
25. }
26.  
27. private static void json2JsonObject() {
28. String s = "{\"name\":\"peter\"}";
29. JSONObject object = JSON.parseObject(s);
30. System.out.println(object.get("name"));
31. }
32.  
33. private static void json2JavaBean() {
34. String s = "{\"id\":\"17051801\",\"name\":\"lucy\"}";
35. User user = JSON.parseObject(s, User.class);
36. System.out.println(user.getId());
37. System.out.println(user.getName());
38. }
39.  
40. private static void json2JsonArray() {
41. String s = "[{\"id\":\"17051801\",\"name\":\"lucy\"},{\"id\":\"17051802\",\"name\":\"peter\"}]";
42. JSONArray array = JSON.parseArray(s);
43. for (int i = 0; i < array.size(); i++) {
44. //JSONArray中的数据转换为String类型需要在外边加"";不然会报出类型强转异常！
45. String str = array.get(i)+"";
46. JSONObject object = JSON.parseObject(str);
47. System.out.println(object.get("name"));
48. }
49. }
50.  
51. private static void json2JavaBeanList() {
52. String s = "[{\"id\":\"17051801\",\"name\":\"lucy\"},{\"id\":\"17051802\",\"name\":\"peter\"}]";
53. List<User> list = JSON.parseArray(s, User.class);
54. for (User user : list) {
55. System.out.println(user.getName());
56. }
57. }
58.  
59. private static void javaBean2Json() {
60. User user = new User("17051801", "lucy");
61. String string = JSON.toJSONString(user);
62. System.out.println(string);
63. }
64.  
65. private static void javaBean2JsonObject() {
66. User user = new User("17051801", "lucy");
67. JSONObject json = (JSONObject) JSON.toJSON(user);
68. System.out.println(json.get("id"));
69. }
70.  
71. private static void json2ListInMap() {
72. String s = "{json:[{id:\"17051801\",\"name\":\"lucy\"},{id:\"17051802\",\"name\":\"peter\"},"
73. + "{id:\"17051803\",\"name\":\"tom\"},{id:\"17051804\",\"name\":\"lily\"}]}";
74. //将Json字符串转换为JSONObject对象,并取出list对象的值
75. JSONObject object = JSON.parseObject(s);
76. Object objArray = object.get("json");
77. String str = objArray+"";
78. //方式1:转换成JSONArray对象形式
79. JSONArray array = JSON.parseArray(str);
80. for (int i = 0; i < array.size(); i++) {
81. JSONObject obj = JSON.parseObject(array.get(i)+"");
82. System.out.println(obj.get("name"));
83. }
84. //方式2:转换成List<JavaBean>形式
85. List<User> list = JSON.parseArray(str, User.class);
86. for (User user : list) {
87. System.out.println(user.getName());
88. }
89. }
90.  
91. private static void list2JsonInMap() {
92. //方式1:构建一个带有list的JavaBean对象
93. School school = new School();
94. school.setId("1");
95. school.setName("schoolA");
96.  
97. User user1 = new User();
98. user1.setId("17051801");
99. user1.setName("lucy");
100. User user2 = new User();
101. user2.setId("17051802");
102. user2.setName("peter");
103.  
104. school.getStudents().add(user1);
105. school.getStudents().add(user2);
106. //将JavaBean对象转换成Json字符串
107. String string1 = JSON.toJSONString(school);
108. System.out.println(string1);
109.  
110. //方式2:构建一个带有list的Map对象
111. Map<String, Object> map1 = new HashMap<String,Object>();
112. map1.put("id", "17051801");
113. map1.put("name", "lucy");
114.  
115. Map<String, Object> map2 = new HashMap<String,Object>();
116. map2.put("id", "17051802");
117. map2.put("name", "peter");
118.  
119. List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
120. list.add(map1);
121. list.add(map2);
122.  
123. Map<String, Object> map = new HashMap<String,Object>();
124. map.put("id", "1");
125. map.put("name", "schoolA");
126. map.put("students", list);
127. //将map对象转换成Json字符串
128. String string2 = JSON.toJSONString(map);
129. System.out.println(string2);
130. }
131.  
132. private static void stringToMap(){
133. String str = "{\"age\":\"24\",\"name\":\"cool_summer_moon\"}";
134. JSONObject jsonObject = JSONObject.parseObject(str);
135. //json对象转Map
136. Map<String,Object> map = (Map<String,Object>)jsonObject;
137. System.out.println("map对象是：" + map);
138. Object object = map.get("age");
139. System.out.println("age的值是"+object);
140. }
141.  
142. private static void mapToString(){
143. Map<String,Object> map = new HashMap<>();
144. map.put("age", 24);
145. map.put("name", "cool_summer_moon");
146. String jsonString = JSON.toJSONString(map);
147. System.out.println("json字符串是："+jsonString);
148. }
149.  
150. private static void mapToJsonObject(){
151. Map<String,Object> map = new HashMap<>();
152. map.put("age", 24);
153. map.put("name", "cool_summer_moon");
154. JSONObject json = new JSONObject(map);
155. System.out.println("Json对象是：" + json);
156.  
157. }
158.  
159. /**
160. * 测试包装类型的List转换为json字符串
161. */
162. public static void testList2String() {
163. List<Long> longs = new ArrayList<Long>();
164. longs.add(1L);
165. longs.add(2L);
166. longs.add(3L);
167. String actual = JSON.toJSONString(longs);
168. Assert.assertEquals("[1,2,3]", actual);
169. }
170.  
171. }