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Insurance 项目——与移动端交互json-Gson
这是一个java初学者在独立开发一个项目时做的笔记，很多内容仅仅是为了解决当前需求，并未很深入的研究。
什么是Json。
Json是开发领域数据传递的一种。有着数据结构简单，数据字节长度短等优势。
http://www.json.org.cn/
这里主要是用来和移动端做交互，使用了google的Gson。
1、pom
1 <!-- Gson --> 2 <dependency> 3 <groupId>com.google.code.gson</groupId> 4 <artifactId>gson</artifactId> 5 <version>2.3</version> 6 </dependency>
2、序列化
序列化是将对象状态转换为可保持或传输的格式的过程。在这里就是将对象转换成为json。
实体类：
1 public class User { 2 private Integer id; 3 4 private String userName; 5 6 private String password; 7 8 private Integer age; 9 10 public Integer getId() { 11 return id; 12 } 13 14 public void setId(Integer id) { 15 this.id = id; 16 } 17 18 public String getUserName() { 19 return userName; 20 } 21 22 public void setUserName(String userName) { 23 this.userName = userName == null ? null : userName.trim(); 24 } 25 26 public String getPassword() { 27 return password; 28 } 29 30 public void setPassword(String password) { 31 this.password = password == null ? null : password.trim(); 32 } 33 34 public Integer getAge() { 35 return age; 36 } 37 38 public void setAge(Integer age) { 39 this.age = age; 40 } 41 }
测试类：
1 @Test 2 public void test(){ 3 Gson g = new Gson(); 4 User u = new User(); 5 u.setAge(10); 6 u.setId(5); 7 u.setPassword("password"); 8 u.setUserName("username"); 9 String ugson = g.toJson(u); 10 System.out.println(ugson); 11 }
打印结果：{"id":5,"userName":"username","password":"password","age":10}
3、反序列化
反序列化就是将json转换成为对象。
沿用User实体类。
Json：{"id":10,"userName":"jack","password":"jack","age":15}
测试类：
1 @Test 2 public void test(){ 3 String Ujson = "{\"id\":10,\"userName\":\"jack\",\"password\":\"jack\",\"age\":15}"; 4 Gson g = new Gson(); 5 User u = g.fromJson(Ujson, User.class); 6 System.out.println("id:"+u.getId()+",age:"+u.getAge()+",username:"+u.getUserName()+",password:"+u.getPassword()); 7 }
打印结果：id:10,age:15,username:jack,password:jack
4、@Expose
在实体类中，可以给属性加入@Expose注解。在使用GsonBuilder() .excludeFieldsWithoutExposeAnnotation() .create();序列化时，不会对未注解的属性进行序列化。
实体类：
1 public class User { 2 private Integer id; 3 @Expose 4 private String userName; 5 6 private String password; 7 @Expose 8 private Integer age; 9 10 public Integer getId() { 11 return id; 12 } 13 14 public void setId(Integer id) { 15 this.id = id; 16 } 17 18 public String getUserName() { 19 return userName; 20 } 21 22 public void setUserName(String userName) { 23 this.userName = userName == null ? null : userName.trim(); 24 } 25 26 public String getPassword() { 27 return password; 28 } 29 30 public void setPassword(String password) { 31 this.password = password == null ? null : password.trim(); 32 } 33 34 public Integer getAge() { 35 return age; 36 } 37 38 public void setAge(Integer age) { 39 this.age = age; 40 } 41 }
测试类：
1 @Test 2 public void test(){ 3 Gson g = new Gson(); 4 Gson g1 = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create(); 5 User u = new User(); 6 u.setAge(10); 7 u.setId(5); 8 u.setPassword("password"); 9 u.setUserName("username"); 10 String ugson = g.toJson(u); 11 String u1gson = g1.toJson(u); 12 System.out.println("g:"+ugson); 13 System.out.println("g1:"+u1gson); 14 }
打印结果：
g:{"id":5,"userName":"username","password":"password","age":10}
g1:{"userName":"username","age":10}
5、@SerializedName
用来定义属性序列化后的名字。
实体类：
1 public class User { 2 private Integer id; 3 @Expose 4 @SerializedName("name") 5 private String userName; 6 @Expose 7 @SerializedName("pass_word") 8 private String password; 9 @Expose 10 private Integer age; 11 12 public Integer getId() { 13 return id; 14 } 15 16 public void setId(Integer id) { 17 this.id = id; 18 } 19 20 public String getUserName() { 21 return userName; 22 } 23 24 public void setUserName(String userName) { 25 this.userName = userName == null ? null : userName.trim(); 26 } 27 28 public String getPassword() { 29 return password; 30 } 31 32 public void setPassword(String password) { 33 this.password = password == null ? null : password.trim(); 34 } 35 36 public Integer getAge() { 37 return age; 38 } 39 40 public void setAge(Integer age) { 41 this.age = age; 42 } 43 }
测试类：
1 @Test 2 public void test(){ 3 Gson g = new Gson(); 4 Gson g1 = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create(); 5 User u = new User(); 6 u.setAge(10); 7 u.setId(5); 8 u.setPassword("password"); 9 u.setUserName("username"); 10 String ugson = g.toJson(u); 11 String u1gson = g1.toJson(u); 12 System.out.println("g:"+ugson); 13 System.out.println("g1:"+u1gson); 14 }
打印结果：
g:{"id":5,"name":"username","pass_word":"password","age":10}
g1:{"name":"username","pass_word":"password","age":10}
6、@Expose，@SerializedName 反序列化
实体类：
1 public class User { 2 private Integer id; 3 @Expose 4 @SerializedName("name") 5 private String userName; 6 @Expose 7 @SerializedName("pass_word") 8 private String password; 9 @Expose 10 private Integer age; 11 12 public Integer getId() { 13 return id; 14 } 15 16 public void setId(Integer id) { 17 this.id = id; 18 } 19 20 public String getUserName() { 21 return userName; 22 } 23 24 public void setUserName(String userName) { 25 this.userName = userName == null ? null : userName.trim(); 26 } 27 28 public String getPassword() { 29 return password; 30 } 31 32 public void setPassword(String password) { 33 this.password = password == null ? null : password.trim(); 34 } 35 36 public Integer getAge() { 37 return age; 38 } 39 40 public void setAge(Integer age) { 41 this.age = age; 42 } 43 }
测试类：
1 @Test 2 public void test(){ 3 Gson g = new Gson(); 4 Gson g1 = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create(); 5 String Ujson = "{\"id\":10,\"userName\":\"jack\",\"password\":\"jack\",\"age\":15}"; 6 String U1json = "{\"id\":10,\"name\":\"jack\",\"pass_word\":\"jack\",\"age\":15}"; 7 User gUser = g.fromJson(Ujson, User.class); 8 User g1User = g1.fromJson(Ujson, User.class); 9 User gU1ser = g.fromJson(U1json, User.class); 10 User g1U1ser = g1.fromJson(U1json, User.class); 11 System.out.println("gUser:{id:"+gUser.getId()+",age:"+gUser.getAge()+",username:"+gUser.getUserName()+",password:"+gUser.getPassword()+"}"); 12 System.out.println("g1User:{id:"+g1User.getId()+",age:"+g1User.getAge()+",username:"+g1User.getUserName()+",password:"+g1User.getPassword()+"}"); 13 System.out.println("gU1ser:{id:"+gU1ser.getId()+",age:"+gU1ser.getAge()+",username:"+gU1ser.getUserName()+",password:"+gU1ser.getPassword()+"}"); 14 System.out.println("g1U1ser:{id:"+g1U1ser.getId()+",age:"+g1U1ser.getAge()+",username:"+g1U1ser.getUserName()+",password:"+g1U1ser.getPassword()+"}"); 15 }
打印结果：
gUser:{id:10,age:15,username:null,password:null}
g1User:{id:null,age:15,username:null,password:null}
gU1ser:{id:10,age:15,username:jack,password:jack}
g1U1ser:{id:null,age:15,username:jack,password:jack}
使用了@SerializedName 注解来定义属性名，必须使用。
@Expose可以选择使用New Gson()不用；
Insurance 项目——与移动端交互json-Gson
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