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]]