java解析和读取JSON

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。

　　如：{"sex1":"female","name0":"zhangsan"}，表示的是一个JSON对象，里面有两组数据(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
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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) {

JsonConfig jsonConfig = new JsonConfig();

jsonConfig.setExcludes(excludes);

jsonConfig.setIgnoreDefaultExcludes(false);

jsonConfig.setCycleDetectionStrategy(CycleDetectionStrategy.LENIENT);

jsonConfig.registerJsonValueProcessor(Date.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) {

JSONObject json = null;

// 转换include里的属性

if (nory){

Field[] fields = obj.getClass().getDeclaredFields();

String str = "";

for (Field field : fields) {

str += ("#" + field.getName());

}

fields = obj.getClass().getSuperclass().getDeclaredFields();

for (Field field : fields) {

str += ("#" + field.getName());

}

str += "#";

for (String s : include) {

str = str.replace("#" + s + "#", "#");

}

json = JSONObject.fromObject(obj, configJson(str.split(":")));

}

// 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) {

StringBuffer temp = new StringBuffer();

temp.append("[");

int size = list.size();

for (int i = 0; i < size; i++) {

temp.append(obj2JsonString(list.get(i)) + ((i < size - 1) ? "," : ""));

}

temp.append("]");

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) {

StringBuffer rest = new StringBuffer();

rest.append("[");

int size = beans.size();

for (int i = 0; i < size; i++) {

rest.append(obj2JsonString(beans.get(i), include, nory) + ((i < size - 1) ? "," : ""));

}

rest.append("]");

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) {

String s_json = "{";

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) {

s_json += ("\"" + key + "\":" + JsonUtil.list2JsonString((List<E>) map.get(key), include, nory));

} else {

JSONObject json = JSONObject.fromObject(map.get(key));

s_json += ("\"" + key + "\":" + json.toString());

}

if (it.hasNext()) {

s_json += ",";

}

}

s_json += "}";

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;

Map<E, V> valueMap = 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();

List<T> list = 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);

String[] stringArray = 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();

Long[] longArray = 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();

Integer[] integerArray = 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();

Double[] doubleArray = new Double[size];

for (int i = 0; i < size; i++) {

doubleArray[i] = jsonArray.getDouble(i);

}

return doubleArray;

}

public static void main(String[] args) {

User user = new User();

user.setUsername("admin");

user.setPassword("123");

user.setAge(20);

User user2 = new User();

user2.setUsername("admin2");

user2.setPassword("123456");

user2.setAge(24);

System.out.println("一：" + JsonUtil.obj2JsonString(user));

Map<String, String> map11 = new HashMap<String, String>();

map11.put("1", "a");

map11.put("2", "b");

System.out.println("二：" + JsonUtil.obj2JsonString(map11));

System.out.println("****************************************************************");

List<User> list = new ArrayList<User>();

list.add(user);

list.add(user2);

System.out.println("三：" + JsonUtil.list2JsonString(list));

System.out.println("四：" + JsonUtil.list2JsonString_(list));

System.out.println("****************************************************************");

// 只包含数组里面的属性

System.out.println("五：" + JsonUtil.obj2JsonString(user, new String[] { "username" }, true));

// 除数组之外的所有属性

System.out.println("六：" + JsonUtil.obj2JsonString(user, new String[] { "username" }, false));

System.out.println("七：" + JsonUtil.list2JsonString(list, new String[] { "username", "password" }, true));

System.out.println("****************************************************************");

Map<String, User> map1 = new HashMap<String, User>();

map1.put("1", user);

map1.put("2", user2);

System.out.println("八：" + JsonUtil.map2JsonString(map1, new String[] { "username", "password" }, true));

Map<String, List<User>> map2 = new HashMap<String, List<User>>();

map2.put("1", list);

System.out.println("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"}]}