Android解析JSON方式

JSON數據格式的定義：

JSON的全稱是：JavaScript Object Notation，是一種輕量級的數據交換格式。它構建於兩種結構：

1、"名稱/值" 對的集合(a collection of name / value pairs)。不同的語言中，它被理解為對象(Object)，記錄(Record)，結構(struct)，字典(Dictionary)，哈希表(HashTable)，有鍵列表(Keyed list)，或者關聯數組(Associative array)。

2、值的有序列表(An ordered list of values)。在大部分語言中，它被理解為數組(array)。

JSON數據格式的特點：

JSON對象時一個無序的" '名稱/值' 對"的集合，一個對象以“{”(左括號)開始， 以"}"(右括號)結束，每個"名稱"後跟一個"："(冒號)，名稱/值 對之間使用"，"(逗號)分隔。

如：

{

"name":"jackson",

"age":100

}

稍微復雜一點的情況，數組是值的有序集合，一個數組以“[”(左中括號)開始，以"]"(右中括號)結束。值之間使用","(逗號)分隔。

如：

{

"studengs":

[

{"name": "jackson", "age": 100},

{"name": "michael", "age": 51},

]

}

首先，我們搭建一個服務器的工程：JsonProject這個項目，工程目錄結構：

源代碼：

Person.java

1. package com.json.domain;
3. public class Person {
4. private int id;
5. private String name;
6. private String address;
8. public Person() {
9. super();
10. }
11. public Person(int id, String name, String addrss) {
12. super();
13. this.id = id;
14. this.name = name;
15. this.address = addrss;
16. }
17. public int getId() {
18. return id;
19. }
20. public void setId(int id) {
21. this.id = id;
22. }
23. public String getName() {
24. return name;
25. }
26. public void setName(String name) {
27. this.name = name;
28. }
29. public String getAddress() {
30. return address;
31. }
32. public void setAddress(String address) {
33. this.address = address;
34. }
35. @Override
36. public String toString() {
37. return "Person [addrss=" + address + ", id=" + id + ", name=" + name
38. + "]";
39. }
41. }

JsonService.java

1. package com.json.service;
3. import java.util.ArrayList;
4. import java.util.HashMap;
5. import java.util.List;
6. import java.util.Map;
8. import com.json.domain.Person;
10. public class JsonService {
12. public JsonService() {
13. }
15. public Person getPerson(){
16. Person person = new Person(1001,"jack","上海黃浦區");
17. return person;
18. }
19. public List<Person> getListPerson(){
20. List<Person> list = new ArrayList<Person>();
21. Person person1 = new Person(1001,"jack","上海黃浦區");
22. Person person2 = new Person(1002,"rose","上海闵行區");
23. Person person3 = new Person(1003,"mick","上海黃浦區");
24. list.add(person1);
25. list.add(person2);
26. list.add(person3);
27. return list;
28. }
30. public List<String> getListString(){
31. List<String> list = new ArrayList<String>();
32. list.add("北京");
33. list.add("上海");
34. list.add("湖南");
35. return list;
36. }
38. public List<Map<String,Object>> getListMaps(){
39. List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();
40. Map<String,Object> map1 = new HashMap<String, Object>();
41. Map<String,Object> map2 = new HashMap<String, Object>();
42. map1.put("id", 1001);
43. map1.put("name", "jack");
44. map1.put("address", "北京");
45. map2.put("id", 1001);
46. map2.put("name", "rose");
47. map2.put("address", "上海");
48. list.add(map1);
49. list.add(map2);
50. return list;
51. }
52. }

JsonServlet.java

1. package com.json.servlet;
3. import java.io.IOException;
4. import java.io.PrintWriter;
6. import javax.servlet.ServletException;
7. import javax.servlet.http.HttpServlet;
8. import javax.servlet.http.HttpServletRequest;
9. import javax.servlet.http.HttpServletResponse;
11. import com.json.service.JsonService;
12. import com.json.tools.JsonTools;
14. public class JsonServlet extends HttpServlet {
15. private JsonService service;
16. /**
17. * Constructor of the object.
18. */
19. public JsonServlet() {
20. super();
21. }
23. /**
24. * Destruction of the servlet. <br>
25. */
26. public void destroy() {
27. super.destroy(); // Just puts "destroy" string in log
28. // Put your code here
29. }
31. /**
32. * The doGet method of the servlet. <br>
33. *
34. * This method is called when a form has its tag value method equals to get.
35. *
36. * @param request the request send by the client to the server
37. * @param response the response send by the server to the client
38. * @throws ServletException if an error occurred
39. * @throws IOException if an error occurred
40. */
41. public void doGet(HttpServletRequest request, HttpServletResponse response)
42. throws ServletException, IOException {
44. this.doPost(request, response);
45. }
47. /**
48. * The doPost method of the servlet. <br>
49. *
50. * This method is called when a form has its tag value method equals to post.
51. *
52. * @param request the request send by the client to the server
53. * @param response the response send by the server to the client
54. * @throws ServletException if an error occurred
55. * @throws IOException if an error occurred
56. */
57. public void doPost(HttpServletRequest request, HttpServletResponse response)
58. throws ServletException, IOException {
60. response.setContentType("text/html;charset=utf-8");
61. request.setCharacterEncoding("utf-8");
62. response.setCharacterEncoding("utf-8");
63. PrintWriter out = response.getWriter();
65. String jsonString = "";
66. String action_flag = request.getParameter("action_flag");
67. if(action_flag.equals("person")){
68. jsonString = JsonTools.createJsonString("person", service.getPerson());
69. }else if(action_flag.equals("persons")){
70. jsonString = JsonTools.createJsonString("persons", service.getListPerson());
71. }else if(action_flag.equals("listString")){
72. jsonString = JsonTools.createJsonString("listString", service.getListString());
73. }else if(action_flag.equals("listMap")){
74. jsonString = JsonTools.createJsonString("listMap", service.getListMaps());
75. }
76. out.println(jsonString);
77. out.flush();
78. out.close();
79. }
81. /**
82. * Initialization of the servlet. <br>
83. *
84. * @throws ServletException if an error occurs
85. */
86. public void init() throws ServletException {
87. service = new JsonService();
88. }
90. }

web.xml中servlet映射

1. <servlet>
2. <description>This is the description of my J2EE component</description>
3. <display-name>This is the display name of my J2EE component</display-name>
4. <servlet-name>JsonServlet</servlet-name>
5. <servlet-class>com.json.servlet.JsonServlet</servlet-class>
6. </servlet>
8. <servlet-mapping>
9. <servlet-name>JsonServlet</servlet-name>
10. <url-pattern>/servlet/JsonServlet</url-pattern>
11. </servlet-mapping>

我們通過浏覽器

訪問地址一：http://wulianghuan-pc:8080/JsonProject/servlet/JsonServlet?action_flag=person

輸出以下結果：

{"persons":{"address":"上海黃浦區","id":1001,"name":"jack"}}

訪問地址二：http://wulianghuan-pc:8080/JsonProject/servlet/JsonServlet?action_flag=persons

輸出以下結果：

{"persons":[{"address":"上海黃浦區","id":1001,"name":"jack"},{"addrss":"上海闵行區","id":1002,"name":"rose"},{"address":"上海黃浦區","id":1003,"name":"mick"}]}

訪問地址三：http://wulianghuan-pc:8080/JsonProject/servlet/JsonServlet?action_flag=listString

輸出以下結果：

{"persons":["北京","上海","湖南"]}

訪問地址四：http://wulianghuan-pc:8080/JsonProject/servlet/JsonServlet?action_flag=listMap

輸出以下結果：

{"persons":[{"id":1001,"address":"北京","name":"jack"},{"id":1001,"address":"上海","name":"rose"}]}