使用jackson解析JSON数据

本文介绍使用jackson来对json数据进行解析操作

首先，需要去官网下载jackson，本文使用的是（jackson-all-1.9.11.jar）

主要通过ObjectMapper对json进行处理

 1 package com.whroid.java.json;
 2 
 3 import java.io.IOException;
 4 
 5 
 6 import org.codehaus.jackson.JsonFactory;
 7 import org.codehaus.jackson.JsonGenerationException;
 8 import org.codehaus.jackson.JsonParseException;
 9 import org.codehaus.jackson.map.JsonMappingException;
10 import org.codehaus.jackson.map.ObjectMapper;
11 import org.codehaus.jackson.map.SerializationConfig;
12 
13 
14 public class JacksonUtil {
15     
16      ObjectMapper mObjectMapper;
17     JsonFactory mJsonFactory;
18     static JacksonUtil mJacksonUtil;
19     public static JacksonUtil getInstance()
20     {
21         if(mJacksonUtil == null)
22         {
23             mJacksonUtil = new JacksonUtil();
24         }
25         return mJacksonUtil;
26     }
27     private JacksonUtil()
28     {
29         mObjectMapper = new ObjectMapper();
30         mObjectMapper.configure(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS, false);//（禁止SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS）
31         mJsonFactory = mObjectMapper.getJsonFactory();
32     }
33     
34 
35     /**
36      * 将json字符串数据，转换成cls类实例。需要保证cls类中的属性和json中相对应，并且cls中必须有相应的getter()/setter()方法
37      * @param json
38      * @param cls
39      * @return
40      * @throws JsonParseException
41      * @throws IOException
42      */
43     public   <T extends Object>  T  jsonToObject(String json,Class<T> cls) throws JsonParseException, IOException
44     {
45         return mObjectMapper.readValue(json, cls);
46     }
47     /**
48      * 将实例对象，转化成json字符串。需要保证cls类中的属性和json中相对应，并且cls中必须有相应的getter()/setter()方法
49      * @param obj
50      * @return
51      * @throws JsonGenerationException
52      * @throws JsonMappingException
53      * @throws IOException
54      */
55     public  String  objectToJson(Object obj) throws JsonGenerationException, JsonMappingException, IOException
56     {
57         return mObjectMapper.writeValueAsString(obj);
58     }
59 }

与json转化的对象类JSONBean,需要添加getter()/setter()方法

 1 package com.whroid.java.json;
 2 
 3 import java.util.ArrayList;
 4 import java.util.List;
 5 
 6 
 7 public class JSONBean {
 8 
 9     private String name  = "name";
10     private int id = 1;
11     private List<String> list = new ArrayList<String>();
12     private boolean b;
13     SubBean subBean = new SubBean();
14     public String getName() {
15         return name;
16     }
17     public void setName(String name) {
18         this.name = name;
19     }
20     
21     public int getId() {
22         return id;
23     }
24     public void setId(int id) {
25         this.id = id;
26     }
27     
28     public List<String> getList() {
29         return list;
30     }
31     public void setList(List<String> list) {
32         this.list = list;
33     }
34     public boolean isB() {
35         return b;
36     }
37     public void setB(boolean b) {
38         this.b = b;
39     }
40     public SubBean getSubBean() {
41         return subBean;
42     }
43     public void setSubBean(SubBean subBean) {
44         this.subBean = subBean;
45     }
46     @Override
47     public String toString() {
48         return "JSONBean [name=" + name + ", id=" + id + ", list=" + list
49                 + ", b=" + b + ", subBean=" + subBean + "]";
50     }
51     
52     
53 }
54 class SubBean{
55     String subname = "subname";
56 
57     public String getSubname() {
58         return subname;
59     }
60 
61     public void setSubname(String subname) {
62         this.subname = subname;
63     }
64 
65     @Override
66     public String toString() {
67         return "SubBean [subname=" + subname + "]";
68     }
69     
70 }

调用

 1 public static void main(String[] args) {
 2         
 3         JSONBean bean = new JSONBean();
 4         String jackson = null;
 5         try {
 6             jackson = JacksonUtil.getInstance().objectToJson(bean);
 7             System.out.println("jackson:"+jackson);
 8             
 9             bean = JacksonUtil.getInstance().jsonToObject(jackson, JSONBean.class);
10             System.out.println("bean:"+bean);
11         } catch (Exception e) {
12             e.printStackTrace();
13         }
14         
15     }

jackson:{"name":"name","id":1,"list":[],"b":false,"subBean":{"subname":"subname"}}

//使用上面那段json解析后的对象
bean:JSONBean [name=name, id=1, list=[], b=false, subBean=SubBean [subname=subname]]