java生成json字符串的方法
转 http://www.cnblogs.com/zhujiabin/p/5498555.html
例1：将map对象添加一次元素（包括字符串对、数组），转换成json对象一次。
代码：
package com.json;
//这是使用org.json的程序：
import java.util.HashMap;
import java.util.Map;
import org.json.JSONException;
import org.json.JSONObject;
public class jsontest {
public static void main(String[] args) throws JSONException {
String json = "{'name':'reiz'}";
JSONObject jsonObj = new JSONObject(json);
String name = jsonObj.getString("name");
System.out.println(jsonObj);
jsonObj.put("initial", name.substring(0, 1).toUpperCase());
String[] likes = new String[] { "JavaScript", "Skiing", "Apple Pie" };
jsonObj.put("likes", likes);
System.out.println(jsonObj);
Map ingredients = new HashMap ();
ingredients.put("apples", "3kg");
ingredients.put("sugar", "1kg");
ingredients.put("pastry", "2.4kg");
ingredients.put("bestEaten", "outdoors");
jsonObj.put("ingredients", ingredients);
System.out.println(jsonObj);
}
}
运行结果：
{
"name"
:
"reiz"
}{
"initial"
:
"R"
,
"likes"
:[
"JavaScript"
,
"Skiing"
,
"Apple Pie"
],
"name"
:
"reiz"
}{
"ingredients"
:{
"apples"
:
"3kg"
,
"pastry"
:
"2.4kg"
,
"bestEaten"
:
"outdoors"
,
"sugar"
:
"1kg"
},
"initial"
:
"R"
,
"likes"
:[
"JavaScript"
,
"Skiing"
,
"Apple Pie"
],
"name"
:
"reiz"
}
（需要用到的包可在官网下载：http://www.json.org/java/index.html）
例2：list转换成json的三种参数形式。
import java.util.ArrayList;import java.util.List; import net.sf.json.JSONArray;import net.sf.json.JSONObject;
public
class
listToJson {
public
static
void
main(String[] args) { boolean[] boolArray =
new
boolean[]{
true
,
false
,
true
};JSONArray jsonArray1 = JSONArray.fromObject( boolArray );System.
out
.println( jsonArray1 );
// prints [true,false,true]
List list =
new
ArrayList();list.add(
"first"
);list.add(
"second"
);JSONArray jsonArray2 = JSONArray.fromObject( list );System.
out
.println( jsonArray2 );
// prints ["first","second"]
JSONArray jsonArray3 = JSONArray.fromObject(
"['json','is','easy']"
);System.
out
.println( jsonArray3 );
// prints ["json","is","easy"]
}}
运行结果：
[
true
,
false
,
true
][
"first"
,
"second"
][
"json"
,
"is"
,
"easy"
]
例3：json转换成list和map。
package com.json; import java.util.Collection;import java.util.Map;import java.util.Map.Entry; import net.sf.json.JSONArray;import net.sf.json.JSONObject;
public
class
jsonToListandMap {
public
static
void
main(String[] args) {
// TODO Auto-generated method stub
String listStr =
"[\"apple\",\"orange\"]"
; Collection strlist = JSONArray.toCollection(JSONArray.fromObject(listStr));
for
(String str : strlist) { System.
out
.println(str); } String mapStr =
"{\"age\":30,\"name\":\"Michael\",\"baby\":[\"Lucy\",\"Lily\"]}"
; Map map = (Map) JSONObject.toBean(JSONObject .fromObject(mapStr), Map.
class
);
for
(Entry entry : map.entrySet()) { System.
out
.println(entry.getKey() +
"
"
+ entry.getValue()); } } }
运行结果：
appleorangename Michaelage
30
baby [Lucy, Lily]