使用Hashtable和List结合拼json数据

在做项目的时候，有时候需要向页面返回一个特定的json类型的数据，一般情况下会有下面的方法进行拼接：

public String chongzhiList() throws Exception {
List list = new ArrayList();
if (StringUtils.isNotEmpty(psCode)) {

list = totalQuantityManager.findPsList(psCode);
}
//创建StringBuffer类型的变量json，用于存放拼装好的json数据
StringBuffer json = new StringBuffer("[");
//如果list不为空则执行if内的for循环
if(list!=null && list.size()>0){
for(int i=0;i<list.size();i++){
Object[] strs = (Object[]) list.get(i);
json.append("{\"id\":" + "\"" + strs[0] + "\",");
json.append("\"wuranwu\":" + "\"" + strs[1] + "\",");
json.append("\"danwei\":" + "\"" + strs[2] + "\",");
json.append("\"yipaifangliang\":" + "\"" + strs[3] + "\",");
json.append("\"chongzhiliang\":" + "\"" + strs[4] + "\",");
json.append("\"xukeliang\":" + "\"" + strs[5] + "\",");
json.append("\"yuliang\":" + "\"" + strs[6] + "\",");
json.append("\"icyuliang\":" + "\"" + strs[7] + "\"}");
if(i<list.size()-1){
json.append(",");
}
}
}
json.append("]");
this.jsonObject = json.toString();
return JSON;
}

这种方式在碰到更加复杂的情况下就显得力不从心了，会经常出现一些少逗号，多括号的问题，下面介绍一种方法拼接特定的json类型数据：

利用Hashtable和List结合，使用JSONObject类进行转化的方式会更加的方便，相关文章链接：JSONObject和JSONArray

1.拼出给定的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
]
}

方法如下：

public String getMonthFlow() throws Exception{
//创建List对象用来存放接收结果集
List list = new ArrayList();
list = totalQuantityManager.getMonthFlow();
//创建list1,list2,list3,list4分别用来存放每一条数据中的特定值
ArrayList list1 = new ArrayList();
ArrayList list2 = new ArrayList();
ArrayList list3 = new ArrayList();
ArrayList list4 = new ArrayList();

//for循环用来循环每一条数据，从每一条数据中取出特定的数据放入集合中
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]);
}

//创建一个哈希表对象，用于装载键值对形式的数据
Hashtable dic = new Hashtable();
dic.put("huaXue",list1);
dic.put("anDan",list2);
dic.put("erYangHualiu",list3);
dic.put("danYangHuawu",list4);
//利用JSONObject类将哈希表对象转换为json类型的数据
this.jsonObject=JSONObject.fromObject(dic).toString();
return JSON;
}

2.转换下面类型的json数据

{
"type0": [
{
"month": 1,
"value": 400
},
{
"month": 2,
"value": 1132
},
{
"month": 3,
"value": 601
},
{
"month": 4,
"value": 500
},
{
"month": 5,
"value": 120
},
{
"month": 6,
"value": 90
},
{
"month": 7,
"value": 1000
}
],
"type1": [
{
"month": 1,
"value": 400
},
{
"month": 2,
"value": 1132
},
{
"month": 3,
"value": 601
},
{
"month": 4,
"value": 500
},
{
"month": 5,
"value": 120
},
{
"month": 6,
"value": 90
},
{
"month": 7,
"value": 1000
}
],
"type2": [
{
"month": 1,
"value": 400
},
{
"month": 2,
"value": 1132
},
{
"month": 3,
"value": 601
},
{
"month": 4,
"value": 500
},
{
"month": 5,
"value": 120
},
{
"month": 6,
"value": 90
},
{
"month": 7,
"value": 1000
}
],
"type3": [
{
"month": 1,
"value": 400
},
{
"month": 2,
"value": 1132
},
{
"month": 3,
"value": 601
},
{
"month": 4,
"value": 500
},
{
"month": 5,
"value": 120
},
{
"month": 6,
"value": 90
},
{
"month": 7,
"value": 1000
}
]
}

方法如下：

public String getMonthFlow() throws Exception{
//方法一：
//月份
String month = "";
List list = new ArrayList();
list = totalQuantityManager.getMonthFlow();

ArrayList list1 = new ArrayList();
ArrayList list2 = new ArrayList();
ArrayList list3 = new ArrayList();
ArrayList list4 = new ArrayList();

Hashtable dic1 = new Hashtable();
Hashtable dic2 = new Hashtable();
Hashtable dic3 = new Hashtable();
Hashtable dic4 = new Hashtable();

for (int i = 0; i < 4*list.size(); i++) {
Object[] strs = (Object[]) list.get(i%7);
String monTH = "";
if (strs[0]!=null) {
monTH = strs[0].toString().substring(4);
}
if ("01".equals(monTH)) {
month = "1";
}else if ("02".equals(monTH)) {
month = "2";
}else if ("03".equals(monTH)) {
month = "3";
}else if ("04".equals(monTH)) {
month = "4";
}else if ("05".equals(monTH)) {
month = "5";
}else if ("06".equals(monTH)) {
month = "6";
}else if ("07".equals(monTH)) {
month = "7";
}else if ("08".equals(monTH)) {
month = "8";
}else if ("09".equals(monTH)) {
month = "9";
}else if ("10".equals(monTH)) {
month = "10";
}else if ("11".equals(monTH)) {
month = "11";
}else if ("12".equals(monTH)) {
month = "12";
}
if (i/7==0) {
dic1.put("month", month);
dic1.put("value", strs[1]);
list1.add(dic1);
dic1 = new Hashtable();
}else if (i/7==1) {
dic2.put("month", month);
dic2.put("value", strs[2]);
list2.add(dic2);
dic2 = new Hashtable();
}else if (i/7==2){
dic3.put("month", month);
dic3.put("value", strs[3]);
list3.add(dic3);
dic3 = new Hashtable();
}else if (i/7==3) {
dic4.put("month", month);
dic4.put("value", strs[4]);
list4.add(dic4);
dic4 = new Hashtable();
}
}
//哈希表对象（存放键值对（））
Hashtable dic = new Hashtable();
dic.put("type0",list1);
dic.put("type1",list2);
dic.put("type2",list3);
dic.put("type3",list4);
this.jsonObject=JSONObject.fromObject(dic).toString();

/*        //方法二：
List list = new ArrayList();
list = totalQuantityManager.getMonthFlow();
Hashtable dic = new Hashtable();
for(int j=0;j<4;j++){
ArrayList list_s = new ArrayList();
//循环行
for (int i = 0; i < list.size(); i++) {
Object[] strs = (Object[]) list.get(i);
Hashtable dic1 = new Hashtable();
dic1.put("month", strs[0]);
dic1.put("value", strs[1]);
list1.add(dic1);
Hashtable dic2 = new Hashtable();
dic2.put("month", strs[0]);
dic2.put("value", strs[2]);
Hashtable dic3 = new Hashtable();
dic3.put("month", strs[0]);
dic3.put("value", strs[3]);
Hashtable dic4 = new Hashtable();
dic4.put("month", strs[0]);
dic4.put("value", strs[4]);

}
dic.put("type"+j,list_s);
}
this.jsonObject=JSONObject.fromObject(dic).toString();*/
return JSON;
}