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JSON解析实例——使用Json-lib

代码小姐 2022-02-23 阅读 62


Json-lib下载及使用 

  本文介绍用一个类库进行JSON解析。 

  工具下载地址:​​http://sourceforge.net/projects/json-lib/?source=directory​​ 

  下载后,有这么三个东东:

JSON解析实例——使用Json-lib_字段

  将​第一个Jar​包导入项目即可用其中的API。

  (具体方法:在项目中建立libs文件夹,将第一个包复制进去,然后在Java Build Path里面Add External JARs…) 

  ​第二个包​是文档,直接右键解压缩之后就会得到html文档,入口是index.html,当然也可以利用工具(jd2chm.exe)将其转换为chm格式这样查看更方便。  

  第三个包是源码,感兴趣或者以后碰到问题了可以看看。


附加包:解决 Exception in thread "main" java.lang.NoClassDefFoundError 

  导入了上面的包之后,运行程序会抛出运行时异常:​Exception in thread "main" java.lang.NoClassDefFoundError​。

  搜索之后,才知道还要添加另外的包,我是从这里下载的: 

  如果没有积分,也可以去我的网盘下载:

  ​​http://pan.baidu.com/share/link?shareid=1066468750&uk=2701745266​​

  也就是说,一共需要这么多包:

 JSON解析实例——使用Json-lib_字段_02

   需要把它们全部加入libs文件夹,并且把它们添加进Build Path中。


package com.jsonlib.test;

public class Person {
private int id;
private String name;

public Person() {
}

public Person(int id, String name) {
this.id = id;
this.name = name;
}

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}


@Override
public String toString() {
return "Person [id=" + id + ", name=" + name + "]";
}
}

测试类


package com.jsonlib.test;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import net.sf.json.JSONObject;

public class JSONDataConvert_Test {

/**
* 创建JSON字符串
* @param key
* @param value
* @return
*/
public static String createJsonString(String key, Object value) {
JSONObject jsonObject = new JSONObject();
jsonObject.put(key, value);
return jsonObject.toString();

}

public static void init() {
// 一个用户对象转换
Person person = new Person(001,"大美女");
System.out.println(createJsonString("person", person));

// 用户对象集合转换
List<Person> personList = new ArrayList<Person>();
Person person1 = new Person(001, "刘仁奎");
Person person2 = new Person(002, "牛月月");
personList.add(person1);
personList.add(person2);
System.out.println(createJsonString("personList", personList));

// 字符串集合转换
List<String> stringList = new ArrayList<String>();
stringList.add("X-rapido");
stringList.add("NiuYue");

// list中map集合转换
List<Map<String, String>> mapList = new ArrayList<Map<String, String>>();
for (int i = 0; i < 3; ++i) {
Map<String, String> map = new HashMap<String, String>();
map.put("编号", "id_" + i);
map.put("地址", "Name_" + i);
mapList.add(map);
}
System.out.println(createJsonString("mapList", mapList));
}

public static void main(String[] args) {
init();
}
}

打印输出:


{"person":{"id":1,"name":"大美女"}}
{"personList":[{"id":1,"name":"刘仁奎"},{"id":2,"name":"牛月月"}]}
{"mapList":[{"编号":"id_0","地址":"Name_0"},{"编号":"id_1","地址":"Name_1"},{"编号":"id_2","地址":"Name_2"}]}


实例1(过滤不想要格式化的字段)


/**
* 根据条件查找所有
*
* @param request
* @param response
*/
@RequestMapping("/findAllKiaAnalysisByCondition")
public void findAllKiaAnalysisByCondition(HttpServletRequest request, HttpServletResponse response) {
String startDate = request.getParameter("startDate");
String endDate = request.getParameter("endDate");
String unitName = request.getParameter("unitName");
String themes = request.getParameter("themes");

List<KiaAnalysis> listKiaAnalysis = kiaAnalysisService.findAllKiaAnalysisByCondition(startDate, endDate, unitName, themes);
JsonConfig jsonConfig = new JsonConfig();
jsonConfig.setExcludes(new String []{"sidaluanjian","cnuisance","roaddamage","sdTrash"}); // 过滤json格式化的字段

String json = JSONArray.fromObject(listKiaAnalysis, jsonConfig).toString();
System.out.println(json);

try {
response.setCharacterEncoding("utf-8");
PrintWriter out = response.getWriter();
out.print(json);
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}


结果:

[{"rDate":"2014-12","roaddamage":12,"unitName":"学院路"},{"rDate":"2014-12","roaddamage":31,"unitName":"海淀街道"},{"rDate":"2014-12","roaddamage":13,"unitName":"金水路"}]


实例2(过滤Bean对象中字段为空,或字段的值为空的字段)

例:Test test = new Test();

    test.setId("1");

    test.setName("zhangsan");

    jsonObject.fromobject(test,Test.class).toString;

输出:{"id":"1","name":"zhangsan"}


假如不封装name属性,只封装id属性

    Test test = new Test();

    test.setId("1");

    jsonObject.fromobject(test,Test.class).toString;

输出:{"id":"1","name":""}

如果只输出:{"id":"1"} 这样的json字符,解决方法如下代码

public static void main(String[] args) {
Test t = new Test();
t.id = 10;

JsonConfig jsonConfig = new JsonConfig();
PropertyFilter filter = new PropertyFilter() {
public boolean apply(Object object, String fieldName, Object fieldValue) {
return null == fieldValue || "" == fieldValue;
}
};
jsonConfig.setJsonPropertyFilter(filter);
System.out.println(JSONObject.fromObject(t, jsonConfig).toString());
}

如果未给对象赋值用fieldName即可,如果值默认为空,设置fieldValue即可



实例3,把json对象转换简单Bean对象,使用toBean()方法

String jsonString = "{age:'23',country:'china',name:'junxie'}";
JSONObject jsonObject = JSONObject.fromObject(jsonString);
User user = (User) JSONObject.toBean(jsonObject, User.class);
System.out.println(user.getName());
// 结果:打印的name为 junxie

实例4,把json对象转换复杂bean对象

public class TranslateResult {
private String from; // 实际采用的源语言
private String to; // 实际采用的目标语言
private List<ResultPair> trans_result; // 结果体
}
public class ResultPair {
private String src; // 原文
private String dst; // 译文
}

main方法

StringBuffer sb = new StringBuffer();
String json = "{\"from\":\"en\",\"to\":\"zh\",\"trans_result\":[{\"src\":\"hello\",\"dst\":\"您好\"},{\"src\":\"beautiful\",\"dst\":\"美女\"}]}";
Map<String, Class<ResultPair>> map = new HashMap<String, Class<ResultPair>>();
map.put("trans_result", ResultPair.class);
TranslateResult translateResult = (TranslateResult) JSONObject.toBean(JSONObject.fromObject(json), TranslateResult.class, map);
List<ResultPair> list = translateResult.getTrans_result();
for (ResultPair rp : list) {
sb.append(rp.getDst());
}
System.out.println(sb); // 输出:你好美女


默认json-lib会将Bean的字段首字母小写即便定义时候是大写开头,所以可以使用以下方法将json输出的字段转换为首字母大写

// 使用PropertyNameProcessor处理属性首字母大写问题,默认转换首字母会小写 
PropertyNameProcessor propertyNameProcessor = new PropertyNameProcessor() {
@Override
public String processPropertyName(Class target, String fieldName) {
return fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1);
}
};
jsonConfig.registerJsonPropertyNameProcessor(V_FirstPaymentMobilePwdIn.class, propertyNameProcessor);


String json = JSONObject.fromObject(model,jsonConfig).toString();





参考资料


  Json-lib工具类库下载地址

   ​​http://sourceforge.net/projects/json-lib/?source=directory​​

   ​​http://sourceforge.net/projects/json-lib/files/json-lib/json-lib-2.4/​​

​百度网盘中全部Json-lib资源下载:

   ​​http://pan.baidu.com/share/link?shareid=1066468750&uk=2701745266​​



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