writeValueAsString封装成工具类

封装成工具类

1. <span style="font-family:Microsoft YaHei;">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. </span>

public static String toJsonByObject(Object obj){
		String jsonStr = null;
		try {
			jsonStr =  mapper.writeValueAsString(obj);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return jsonStr;
	}
	

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

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