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

 package com.whroid.java.json;

 import java.io.IOException;

 import org.codehaus.jackson.JsonFactory;
 import org.codehaus.jackson.JsonGenerationException;
 import org.codehaus.jackson.JsonParseException;
 import org.codehaus.jackson.map.JsonMappingException;
 import org.codehaus.jackson.map.ObjectMapper;
 import org.codehaus.jackson.map.SerializationConfig;

 public class JacksonUtil {

      ObjectMapper mObjectMapper;
     JsonFactory mJsonFactory;
     static JacksonUtil mJacksonUtil;
     public static JacksonUtil getInstance()
     {
         if(mJacksonUtil == null)
         {
             mJacksonUtil = new JacksonUtil();
         }
         return mJacksonUtil;
     }
     private JacksonUtil()
     {
         mObjectMapper = new ObjectMapper();
         mObjectMapper.configure(SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS, false);//（禁止SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS）
         mJsonFactory = mObjectMapper.getJsonFactory();
     }

     /**
      * 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
      * @param json
      * @param cls
      * @return
      * @throws JsonParseException
      * @throws IOException
      */
     public   <T extends Object>  T  jsonToObject(String json,Class<T> cls) throws JsonParseException, IOException
     {
         return mObjectMapper.readValue(json, cls);
     }
     /**
      * 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
      * @param obj
      * @return
      * @throws JsonGenerationException
      * @throws JsonMappingException
      * @throws IOException
      */
     public  String  objectToJson(Object obj) throws JsonGenerationException, JsonMappingException, IOException
     {
         return mObjectMapper.writeValueAsString(obj);
     }
 }

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

 package com.whroid.java.json;

 import java.util.ArrayList;
 import java.util.List;

 public class JSONBean {

     private String name  = "name";
     private int id = 1;
     private List<String> list = new ArrayList<String>();
     private boolean b;
     SubBean subBean = new SubBean();
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }

     public int getId() {
         return id;
     }
     public void setId(int id) {
         this.id = id;
     }

     public List<String> getList() {
         return list;
     }
     public void setList(List<String> list) {
         this.list = list;
     }
     public boolean isB() {
         return b;
     }
     public void setB(boolean b) {
         this.b = b;
     }
     public SubBean getSubBean() {
         return subBean;
     }
     public void setSubBean(SubBean subBean) {
         this.subBean = subBean;
     }
     @Override
     public String toString() {
         return "JSONBean [name=" + name + ", id=" + id + ", list=" + list
                 + ", b=" + b + ", subBean=" + subBean + "]";
     }

 }
 class SubBean{
     String subname = "subname";

     public String getSubname() {
         return subname;
     }

     public void setSubname(String subname) {
         this.subname = subname;
     }

     @Override
     public String toString() {
         return "SubBean [subname=" + subname + "]";
     }

 }

调用

 public static void main(String[] args) {

         JSONBean bean = new JSONBean();
         String jackson = null;
         try {
             jackson = JacksonUtil.getInstance().objectToJson(bean);
             System.out.println("jackson:"+jackson);

             bean = JacksonUtil.getInstance().jsonToObject(jackson, JSONBean.class);
             System.out.println("bean:"+bean);
         } catch (Exception e) {
             e.printStackTrace();
         }

     }

返回：

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]]