JSONObject和JSONArray

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1.从Object到String
 要先用Object对象构造一个JSONObject或者JSONArray对象，然后调用它的toString()方法即可

（1）示例一

Book book=new Book();
 
book.setName("Java");
 
book.setPrice(52.3f);
 
JSONObject object=JSONObject.fromObject(book);
 
System.out.println(object.toString());

（2）示例二

Book book=new Book();
 
book.setName("Java");
 
book.setPrice(52.3f);
 
Book book2=new Book();
 
book2.setName("C");
 
book2.setPrice(42.3f);
 
List list=new ArrayList();
 
list.add(book);
 
list.add(book2);
 
JSONArray arry=JSONArray.fromObject(list);
 
System.out.println(arry.toString());
 
//结果如下：
 
[{"name":"Java","price":52.3},{"name":"C","price":42.3}]

2.从String到Object
 要先用String对象构造一个JSONObject或者JSONArray对象
(1)示例一

String json="{name:'Java',price:52.3}";    
 
JSONObject object=JSONObject.fromObject(json);
 
System.out.println(object.get("name")+" "+object.get("price"));

(2)示例二

String json="[{name:'Java',price:52.3},{name:'C',price:42.3}]";
 
JSONArray array=JSONArray.fromObject(json);
 
for(int i=0;i<array.size();i++){
 
    Map o=(Map)array.get(i);
 
    System.out.println(o.get("name")+" "+o.get("price"));
 
}

3.从String到Bean

(1)单个Bean对象

String json="{name:'Java',price:52.3}";
 
JSONObject object=JSONObject.fromObject(json);
 
Product product=(Product)JSONObject.toBean(object,Product.class);
 
System.out.println(product.getName()+" "+product.getPrice());

(2).Bean的数组

String json="[{name:'Java',price:52.3},{name:'C',price:42.3}]";
 
JSONArray array=JSONArray.fromObject(json);
 
Product[] products=(Product[]) JSONArray.toArray(array,Product.class);
 
for(Product p:products){
 
    System.out.println(p.getName()+" "+p.getPrice());
 
}

使用List和Map集合结合上面方法拼装自定义json数据

    /**
     * 审批状态列表
     * @return json
     * @throws Exception
     */
    public String applyList() throws Exception {
        List<Map<String,String>> list = new ArrayList<Map<String,String>>();
        Map<String,String> map = new HashMap<String, String>();
        map.put("value", "");
        map.put("text", "全部");
        list.add(map);
        map = new HashMap<String, String>();
        map.put("value", "-1");
        map.put("text", "未通过");
        list.add(map);
        map = new HashMap<String, String>();
        map.put("value", "0");
        map.put("text", "主任审批中");
        list.add(map);
        map = new HashMap<String, String>();
        map.put("value", "1");
        map.put("text", "经理审批中");
        list.add(map);
        map = new HashMap<String, String>();
        map.put("value", "2");
        map.put("text", "已通过");
        list.add(map);
        JSONArray arry=JSONArray.fromObject(list);
        this.jsonObject = arry.toString();
        return JSON;
    }

得到如下JSON数据：

[
    {
        "text": "全部",
        "value": ""
    },
    {
        "text": "未通过",
        "value": "-1"
    },
    {
        "text": "主任审批中",
        "value": "0"
    },
    {
        "text": "经理审批中",
        "value": "1"
    },
    {
        "text": "已通过",
        "value": "2"
    }
]

自定义封装JSON操作的类

package com.util;
 
import java.util.List;
 
import java.util.Map;
 
import net.sf.json.JSONArray;
 
import net.sf.json.JSONObject;
 
public class JsonHelper {
 
     //从普通的Bean转换为字符串
 
     public static String getJson(Object o){
 
         JSONObject jo=JSONObject.fromObject(o);
 
         return jo.toString();
 
     }
 
     //从Java的列表转换为字符串
 
     public static String getJson(List list){
 
         JSONArray ja=JSONArray.fromObject(list);
 
        return ja.toString();
 
     }
 
     //从Java对象数组转换为字符串
 
     public static String getJson(Object[] arry){
 
         JSONArray ja=JSONArray.fromObject(arry);
 
         return ja.toString();
 
     }
 
     //从json格式的字符串转换为Map对象
 
     public static Map getObject(String s){
 
         return     JSONObject.fromObject(s);
 
     }
 
     //从json格式的字符串转换为List数组
 
     public static List getArray(String s){
 
         return JSONArray.fromObject(s);
 
     }
 
     //从json格式的字符串转换为某个Bean
 
     public static Object getObject(String s,Class cls){
 
         JSONObject jo=JSONObject.fromObject(s);
 
         return JSONObject.toBean(jo, cls);
 
     }
 
     //从json格式的字符串转换为某类对象的数组
 
     public static Object getArray(String s,Class cls){
 
         JSONArray ja=JSONArray.fromObject(s);
 
         return JSONArray.toArray(ja, cls);
 
     }
 
}

拼json方法：

    /**
     * 统计页面
     * @return
     * @throws Exception
     */
    public String getMonthFlow() throws Exception{
 
        List list = new ArrayList();
        list = totalQuantityManager.getMonthFlow();
        ArrayList list1 = new ArrayList();
        ArrayList list2 = new ArrayList();
        ArrayList list3 = new ArrayList();
        ArrayList list4 = new ArrayList();
        for (int i = 0; i < list.size(); i++) {
            Object[] strs = (Object[]) list.get(i);
            list1.add(strs[1]);
            list2.add(strs[2]);
            list3.add(strs[4]);
            list4.add(strs[5]);
        }
 
        Hashtable dic = new Hashtable();
        dic.put("huaXue",list1);
        dic.put("anDan",list2);
        dic.put("erYangHualiu",list3);
        dic.put("danYangHuawu",list4);
        this.jsonObject=JSONObject.fromObject(dic).toString();
    return JSON;
    }

json数据：

{
  "huaXue": [
    400,
    1132,
    601,
    500,
    120,
    90,
    1000
  ],
  "anDan": [
    1320,
    7000,
    601,
    234,
    120,
    50000,
    20
  ],
  "erYangHualiu": [
    1320,
    1132,
    601,
    234,
    120,
    90,
    20
  ],
  "danYangHuawu": [
    1320,
    1132,
    601,
    234,
    120,
    90,
    20
  ]
}