fastjson与net.sf.json区别
在现在的开发当中，
绝大多数引用阿里巴巴的fastjson。
当然net.sf.json同样可以使用。
一、引入com.alibaba.fastjson包
com.alibaba
fastjson
1.2.66
常用的格式转化：
Student stu = new Student("公众号编程大道", "m", 2);
//Java对象转化为JSON对象
JSONObject jsonObject = (JSONObject) JSONObject.toJSON(stu);
System.out.println("Java对象转化为JSON对象\n" + jsonObject);
//{"name":"公众号编程大道","age":2,"sex":"m"}
Student stu = new Student("公众号编程大道", "m", 2);
//Java对象转换成JSON字符串
String stuString = JSONObject.toJSONString(stu);
System.out.println("Java对象转换成JSON字符串\n" + stuString);
//{"age":2,"name":"公众号编程大道","sex":"m"}
Student stu = new Student("公众号编程大道", "m", 2);
//先转成JSON对象
JSONObject jsonObject = (JSONObject) JSONObject.toJSON(stu);
//JSON对象转换为JSON字符串
String jsonString = jsonObject.toJSONString();
System.out.println("JSON对象转换为JSON字符串\n" + jsonString);
//{"name":"公众号编程大道","age":2,"sex":"m"}
Student stu = new Student("公众号编程大道", "m", 2);
//先转成JSON对象
JSONObject jsonObject = (JSONObject) JSONObject.toJSON(stu);
//JSON对象转换成Java对象
Student student = JSONObject.toJavaObject(jsonObject, Student.class);
System.out.println("JSON对象转换成Java对象\n" + student);
//Student{name='公众号编程大道', sex='m', age=2}
String stuString = "{\"age\":2,\"name\":\"公众号编程大道\",\"sex\":\"m\"}";
//JSON字符串转换成JSON对象
JSONObject jsonObject1 = JSONObject.parseObject(stuString);
System.out.println("JSON字符串转换成JSON对象\n" + jsonObject1);
//{"sex":"m","name":"公众号编程大道","age":2}
String stuString = "{\"age\":2,\"name\":\"公众号编程大道\",\"sex\":\"m\"}";
//JSON字符串转换成Java对象
Student student1 = JSONObject.parseObject(stuString, Student.class);
System.out.println("JSON字符串转换成Java对象\n" + student1);
//Student{name='公众号编程大道', sex='m', age=2}更全面
//Object转json
JSONObject j1 = (JSONObject)JSONObject.toJSON(man1);
//json转Object
Man man3 = JSONObject.parseObject(j2.toJSONString(), Man.class);
String aaa = "{\"name\":\"张三\",\"id\":\"1\"}";
//String转JSONObject
JSONObject j1 = JSONObject.parseObject(aaa);
//JSONObject转String
String bbb = j1.toJSONString();
String aaa = "[{\"name\":\"张三\",\"id\":\"1\"},{\"name\":\"李四\",\"id\":\"2\"}]";
//String转jsonArray
JSONArray jsArr = JSONObject.parseArray(aaa);
// jsonArray转String
String bbb = jsArr.toJSONString();
// list转jsonArray
JSONArray array = JSONArray.parseArray(JSONObject.toJSONString(mans));
// jsonArray转list
List list = JSONObject.parseArray(js2.toJSONString(), Man.class);
二、引入net.sf.json包（解析json精度丢失）
net.sf.json-lib
json-lib
2.4
jdk15
常用的格式转化：
string字符串-------》json数组
String json = “[{‘day1’:’work’,’day2’:26},{‘day1’:123,’day2’:26}]”;
JSONArray jsonArray = JSONArray.fromObject(json);单个json对象转换
String aa = "{user:{name:\"张三\",age:\"20\"}}";
JSONObject obj = JSONObject.fromObject(aa);List 转换成json（Map也可以）
List list = new ArrayList();
jb1.setCol(1);
jb1.setRow(1);
jb1.setValue("xx");
JSONArray ja = JSONArray.fromObject(list); 遍历Json数组
输出每个成员
for(int i=0; i获取每个成员的key及value
JSONObject obj = (JSONObject) jsonArray.get(i);
Iterator it = obj.keys();
while (it.hasNext()) {
String key = it.next().toString();
System.out.println("key ----- "+key);
System.out.println("value ----- "+obj.get(key));
} 增加
JSONObject obj2 = new JSONObject();
obj2.put("day1", "study");
obj2.put("day2", "2");
jsonArray.add(obj2);删除
jsonArray.remove(index);
jsonArray.subList(fromIndex, toIndex)