java将对象以JOSN打印出来 writeValueAsString

封装成工具类

 

1. public static String toJsonByObject(Object obj){

2. String jsonStr = null;

3. try {

4. jsonStr = mapper.writeValueAsString(obj);

5. } catch (IOException e) {

6. // TODO Auto-generated catch block

7. e.printStackTrace();

8. }

9. return jsonStr;

10. }

11.  

 

 

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如何把Java对象转化成json字符串并打印出来呢？

这里就用到了jackon的jar包，使用writeValuesAsString的方法就可以把对角转化成json字符串。

下面通过一个demo，来仔细体会下如何去转化！

1：先建一个javaBean。

 

[java] view plain copy

1. package com.sino.objectmapperdemo;  
2.   
3. public class BaseObject {  
4.     private String userName;  
5.     private String userCode;  
6.     private double weight;  
7.     private int height;  
8.     private boolean sex;  
9.     private String[] array;  
10.     private BaseObject innerBaseObject;  
11.       
12.     public String getUserName() {  
13.         return userName;  
14.     }  
15.     public void setUserName(String userName) {  
16.         this.userName = userName;  
17.     }  
18.     public String getUserCode() {  
19.         return userCode;  
20.     }  
21.     public void setUserCode(String userCode) {  
22.         this.userCode = userCode;  
23.     }  
24.     public double getWeight() {  
25.         return weight;  
26.     }  
27.     public void setWeight(double weight) {  
28.         this.weight = weight;  
29.     }  
30.     public int getHeight() {  
31.         return height;  
32.     }  
33.     public void setHeight(int height) {  
34.         this.height = height;  
35.     }  
36.     public boolean isSex() {  
37.         return sex;  
38.     }  
39.     public void setSex(boolean sex) {  
40.         this.sex = sex;  
41.     }  
42.     public String[] getArray() {  
43.         return array;  
44.     }  
45.     public void setArray(String[] array) {  
46.         this.array = array;  
47.     }  
48.     public BaseObject getInnerBaseObject(){  
49.         return innerBaseObject;  
50.     }  
51.     public void setInnerBaseObject(BaseObject innerBaseObject){  
52.         this.innerBaseObject = innerBaseObject;  
53.     }  
54.       
55.       
56. }  

 

 

2:在MainActivity中，对其进行赋值和转化操作，并打印出来。

 

[java] view plain copy

1. package com.sino.objectmapperdemo;  
2.   
3. import java.io.IOException;  
4. import java.util.ArrayList;  
5. import java.util.HashMap;  
6. import java.util.Map;  
7.   
8. import org.codehaus.jackson.JsonGenerationException;  
9. import org.codehaus.jackson.map.JsonMappingException;  
10. import org.codehaus.jackson.map.ObjectMapper;  
11.   
12. import android.os.Bundle;  
13. import android.app.Activity;  
14. import android.view.Menu;  
15. /** 
16.  * 使用jackon的ObjectMapper的writeValueAsString方法可以把java对象转化成json字符串 
17.  * 输出的结果是：{"array":["80","90","95"],"height":170,"innerBaseObject":{"array":["65","68","75"], 
18.  * "height":171,"innerBaseObject":null,"userCode":"2号","userName":"李四","weight":75.5,"sex":true}, 
19.  * "userCode":"1号","userName":"张三","weight":65.5,"sex":true} 
20.  *  
21.  */  
22. public class MainActivity extends Activity {  
23.   
24.     @Override  
25.     protected void onCreate(Bundle savedInstanceState) {  
26.         super.onCreate(savedInstanceState);  
27.         setContentView(R.layout.activity_main);  
28.     try {  
29.         ObjectMapper objectMapper = new ObjectMapper();  
30. //      ArrayList list = new ArrayList();  
31. //      Map map = new HashMap();  
32.         BaseObject object1 = new BaseObject();  
33.         object1.setUserName("张三");  
34.         object1.setUserCode("1号");  
35.         object1.setWeight(65.5);  
36.         object1.setHeight(170);  
37.         object1.setSex(true);  
38.         String[] score={"80","90","95"};  
39.         object1.setArray(score);  
40.           
41.         BaseObject object2=new BaseObject();    
42.         object2.setUserName("李四");  
43.         object2.setUserCode("2号");  
44.         object2.setWeight(75.5);  
45.         object2.setHeight(171);  
46.         object2.setSex(true);   
47.         score=new String[3];  
48.         score[0]="65";  
49.         score[1]="68";  
50.         score[2]="75";  
51.         object2.setArray(score);  
52. //        object2成为object1的内部类  
53.         object1.setInnerBaseObject(object2);  
54. //        list.add(object1);   
55. //        map.put("baseObject", list);    
56. //        把对象转化成json字符串  
57.         String json = objectMapper.writeValueAsString(object1);  
58.         System.out.println(json);  
59.         } catch (JsonGenerationException e) {  
60.             e.printStackTrace();  
61.         } catch (JsonMappingException e) {  
62.             e.printStackTrace();  
63.         } catch (IOException e) {  
64.             e.printStackTrace();  
65.         }  
66.          
67.           
68.     }  
69.   
70.   
71. }  

每天努力一点，总会有些收获。