java解析和读取JSON

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第零人 2022-12-14 15:29:29 博主文章分类：J2SE ©著作权

文章标签 json java List 文章分类 代码人生

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1.JSON介绍

　　JSON比XML简单，主要体现在传输相同信息的情况下，文件的大小不同。

　　JSON只用于传输信息，XML还可以用于配置文件的使用。

　　JSON中的符号主要有： " , [ {:

2.JSON中的数组和对象

　　2.1数组（JSONArray）

　　数组用一对[]，表示存放的是一般的数组数据。

　　如：["11","22","33"]，表示这是一个JSONArray数组，里面有3个数据：”11“，”22“，”33“。当然可以是复杂的数据，就是所谓的嵌套定义吧。

　　2.对象（JSONObject）

　　对象用一对{}，来表示其中JSON通用的”键-值“对。

键值对)，sex1=female，name0=zhangsan。当然这里键对应的数据值，可以是复杂的JSON对象或者数组。

3.代码示例

[java] view plain copy print ?

package com.somnus.json;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import net.sf.json.JsonConfig;
import net.sf.json.processors.JsDateJsonValueProcessor;
import net.sf.json.util.CycleDetectionStrategy;
/**
* Json与javaBean之间的转换工具类
*
* @author
*
* {@code 现使用json-lib组件实现
* 需要
* json-lib-2.4-jdk15.jar
* ezmorph-1.0.6.jar
* commons-collections-3.1.jar
* commons-lang-2.0.jar
* commons-beanutils-1.9.1.jar
* 支持
* }
*/
public class JsonUtil {
// *************************************以下对象转换为JSON***************************************************************
private static JsonConfig configJson(String[] excludes) {
new JsonConfig();
jsonConfig.setExcludes(excludes);
false);
jsonConfig.setCycleDetectionStrategy(CycleDetectionStrategy.LENIENT);
class, new JsDateJsonValueProcessor());
return jsonConfig;
}
/**
* 将java对象转换成json字符串
*
* @param bean
* @return
*/
public static String obj2JsonString(Object obj) {
JSONObject json = JSONObject.fromObject(obj);
return json.toString();
}
/**
* 将java对象指定的属性转换成json字符串
*
* @param bean
* @param include
* 包含的属性字段值
* @param nory
* @return
*/
public static String obj2JsonString(Object obj, String[] include, boolean nory) {
null;
// 转换include里的属性
if (nory){
Field[] fields = obj.getClass().getDeclaredFields();
"";
for (Field field : fields) {
"#" + field.getName());
}
fields = obj.getClass().getSuperclass().getDeclaredFields();
for (Field field : fields) {
"#" + field.getName());
}
"#";
for (String s : include) {
"#" + s + "#", "#");
}
":")));
}
// 转换除了include里的属性
else {
json = JSONObject.fromObject(obj, configJson(include));
}
return json.toString();
}
/**
* 将java对象List集合转换成json字符串
*
* @param beans
* @return
*/
public static <E> String list2JsonString(List<E> list) {
new StringBuffer();
"[");
int size = list.size();
for (int i = 0; i < size; i++) {
1) ? "," : ""));
}
"]");
return temp.toString();
}
public static <E> String list2JsonString_(List<E> list) {
JSONArray jsonArray = JSONArray.fromObject(list);
return jsonArray.toString();
}
/**
* 将List中所含对象指定的属性转换成json字符串
*
* @param bean
* @param include
* 包含的属性字段值
* @param nory
* @return
*/
public static <E> String list2JsonString(List<E> beans, String[] include, boolean nory) {
new StringBuffer();
"[");
int size = beans.size();
for (int i = 0; i < size; i++) {
1) ? "," : ""));
}
"]");
return rest.toString();
}
/**
* map集合转换成json格式数据
*
* @param map
* @return
*/
@SuppressWarnings("unchecked")
public static <E, V> String map2JsonString(Map<E, V> map, String[] include, boolean nory) {
"{";
for (Iterator<E> it = map.keySet().iterator(); it.hasNext();) {
String key = (String) it.next();
if (map.get(key) == null) {
else if (map.get(key) instanceof List) {
"\"" + key + "\":" + JsonUtil.list2JsonString((List<E>) map.get(key), include, nory));
else {
JSONObject json = JSONObject.fromObject(map.get(key));
"\"" + key + "\":" + json.toString());
}
if (it.hasNext()) {
",";
}
}
"}";
return s_json;
}
// *************************************以下JSON转换为对象***************************************************************
/**
* 从一个JSON 对象字符格式中得到一个java对象
*
* @param jsonString
* @param beanCalss
* @return
*/
@SuppressWarnings("unchecked")
public static <T> T jsonString2Object(String jsonString, Class<T> clazz) {
JSONObject jsonObject = JSONObject.fromObject(jsonString);
T bean = (T) JSONObject.toBean(jsonObject, clazz);
return bean;
}
/**
* 从json HASH表达式中获取一个map，改map支持嵌套功能
*
* @param jsonString
* @return
*/
@SuppressWarnings({ "unchecked" })
public static<E, V> Map<E, V> jsonString2Map(String jsonString) {
JSONObject jsonObject = JSONObject.fromObject(jsonString);
Iterator<E> keyIter = jsonObject.keys();
E key;
V value;
new HashMap<E, V>();
while (keyIter.hasNext()) {
key = (E)keyIter.next();
value = (V)jsonObject.get(key);
valueMap.put(key, value);
}
return valueMap;
}
/**
* 从json对象集合表达式中得到一个java对象列表
*
* @param jsonString
* @param beanClass
* @return
*/
@SuppressWarnings("unchecked")
public static <T> List<T> json2ObjectList(String jsonString, Class<T> beanClass) {
JSONArray jsonArray = JSONArray.fromObject(jsonString);
JSONObject jsonObject;
T bean;
int size = jsonArray.size();
new ArrayList<T>(size);
for (int i = 0; i < size; i++) {
jsonObject = jsonArray.getJSONObject(i);
bean = (T) JSONObject.toBean(jsonObject, beanClass);
list.add(bean);
}
return list;
}
/**
* 从json数组中得到相应java数组
*
* @param jsonString
* @return
*/
public static Object[] jsonToObjectArray(String jsonString) {
JSONArray jsonArray = JSONArray.fromObject(jsonString);
return jsonArray.toArray();
}
/**
* 从json数组中解析出java字符串数组
*
* @param jsonString
* @return
*/
public static String[] jsonToStringArray(String jsonString) {
JSONArray jsonArray = JSONArray.fromObject(jsonString);
new String[jsonArray.size()];
int size = jsonArray.size();
for (int i = 0; i < size; i++) {
stringArray[i] = jsonArray.getString(i);
}
return stringArray;
}
/**
* 从json数组中解析出javaLong型对象数组
*
* @param jsonString
* @return
*/
public static Long[] jsonToLongArray(String jsonString) {
JSONArray jsonArray = JSONArray.fromObject(jsonString);
int size = jsonArray.size();
new Long[size];
for (int i = 0; i < size; i++) {
longArray[i] = jsonArray.getLong(i);
}
return longArray;
}
/**
* 从json数组中解析出java Integer型对象数组
*
* @param jsonString
* @return
*/
public static Integer[] jsonToIntegerArray(String jsonString) {
JSONArray jsonArray = JSONArray.fromObject(jsonString);
int size = jsonArray.size();
new Integer[size];
for (int i = 0; i < size; i++) {
integerArray[i] = jsonArray.getInt(i);
}
return integerArray;
}
/**
* 从json数组中解析出java Double型对象数组
*
* @param jsonString
* @return
*/
public static Double[] jsonToDoubleArray(String jsonString) {
JSONArray jsonArray = JSONArray.fromObject(jsonString);
int size = jsonArray.size();
new Double[size];
for (int i = 0; i < size; i++) {
doubleArray[i] = jsonArray.getDouble(i);
}
return doubleArray;
}
public static void main(String[] args) {
new User();
"admin");
"123");
20);
new User();
"admin2");
"123456");
24);
"一：" + JsonUtil.obj2JsonString(user));
new HashMap<String, String>();
"1", "a");
"2", "b");
"二：" + JsonUtil.obj2JsonString(map11));
"****************************************************************");
new ArrayList<User>();
list.add(user);
list.add(user2);
"三：" + JsonUtil.list2JsonString(list));
"四：" + JsonUtil.list2JsonString_(list));
"****************************************************************");
// 只包含数组里面的属性
"五：" + JsonUtil.obj2JsonString(user, new String[] { "username" }, true));
// 除数组之外的所有属性
"六：" + JsonUtil.obj2JsonString(user, new String[] { "username" }, false));
"七：" + JsonUtil.list2JsonString(list, new String[] { "username", "password" }, true));
"****************************************************************");
new HashMap<String, User>();
"1", user);
"2", user2);
"八：" + JsonUtil.map2JsonString(map1, new String[] { "username", "password" }, true));
new HashMap<String, List<User>>();
"1", list);
"九：" + JsonUtil.map2JsonString(map2, new String[] { "username", "password" }, true));
}
}

打印结果：

一：{"username":"admin","age":20,"password":"123"}
二：{"2":"b","1":"a"}
****************************************************************
三：[{"username":"admin","age":20,"password":"123"},{"username":"admin2","age":24,"password":"123456"}]
四：[
{"username":"admin","age":20,"password":"123"},
{"username":"admin2","age":24,"password":"123456"}
]
****************************************************************
五：{"username":"admin","age":20,"password":"123"}
六：{"age":20,"password":"123"}
七：[{"username":"admin","age":20,"password":"123"},{"username":"admin2","age":24,"password":"123456"}]
****************************************************************
八：{"2":{"username":"admin2","age":24,"password":"123456"},"1":{"username":"admin","age":20,"password":"123"}}
九：{"1":[{"username":"admin","age":20,"password":"123"},{"username":"admin2","age":24,"password":"123456"}]}
****************************************************************
十：[{"username":"admin","age":20,"password":"123"},{"username":"admin2","age":24,"password":"123456"}]
十一：{"2":{"username":"admin2","age":24,"password":"123456"},"1":{"username":"admin","age":20,"password":"123"}}
十二：{"1":[{"username":"admin","age":20,"password":"123"},{"username":"admin2","age":24,"password":"123456"}]}