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
]
}