java与json互相转换(解决日期问题)

JSON 即 JavaScript Object Natation，它是一种轻量级的数据交换格式，非常适合于服务器与 JavaScript 的交互。本文主要讲解下java和JSON之间的转换，特别是解决互相转换遇到日期问题的情况。

一、需要相关的jar包：

json-lib-xxx.jar

ezmorph-xxx.jar

commons-httpclient-xxx.jar

commons-lang-xxx.jar

commons-logging-xxx.jar

commons-collections-xxx.jar

上面的包可以从下面的连接下载：
http://commons.apache.org/index.html http://json-lib.sourceforge.net http://ezmorph.sourceforge.net
二、java-》JSON

1.List-》JSON

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

list.add("apple");

list.add("orange");

JSONArray jarr = JSONArray.fromObject(list);

System.out.println("list->json:" + jarr.toString());

打印结果：list->json:["apple","orange"]

2.Map-》JSON

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Map<String, Object> map = new HashMap<String, Object>();

map.put("name", "Michael");

map.put("baby", new String[] { "Lucy", "Lily" });

map.put("age", 30);

JSONObject jo = JSONObject.fromObject(map);

System.out.println("map->json:" + jo.toString());

打印结果：map->json:{"age":30,"name":"Michael","baby":["Lucy","Lily"]}

3.bean->JSON

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JsonBean bean = new JsonBean();

bean.setName("NewBaby");

bean.setAge(1);

bean.setBorn(new Date());

jo = JSONObject.fromObject(bean);

System.out.println("bean->json:" + jo.toString());

打印结果：bean->json:{"age":1,"born":{"date":10,"day":3,"hours":14,"minutes":14,"month":2,"seconds":1,"time":1268201641228,"timezoneOffset":-480,"year":110},"name":"NewBaby"}

这时你会发现它把bean对象里的util.Date这个类型的所有属性一一转换出来。在实际运用过程中，大多数情况下我们希望能转化为yyyy-MM-dd这种格式，下面就讲一讲如何实现：

首先要写一个新的类JsonDateValueProcessor如下：

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/**

* JSON 日期格式处理（java转化为JSON）

* @author Michael sun

*/

public class JsonDateValueProcessor implements JsonValueProcessor {

/**

* datePattern

*/

private String datePattern = "yyyy-MM-dd";

/**

* JsonDateValueProcessor

*/

public JsonDateValueProcessor() {

super();

}

/**

* @param format

*/

public JsonDateValueProcessor(String format) {

super();

this.datePattern = format;

}

/**

* @param value

* @param jsonConfig

* @return Object

*/

public Object processArrayValue(Object value, JsonConfig jsonConfig) {

return process(value);

}

/**

* @param key

* @param value

* @param jsonConfig

* @return Object

*/

public Object processObjectValue(String key, Object value,

JsonConfig jsonConfig) {

return process(value);

}

/**

* process

* @param value

* @return

*/

private Object process(Object value) {

try {

if (value instanceof Date) {

SimpleDateFormat sdf = new SimpleDateFormat(datePattern,

Locale.UK);

return sdf.format((Date) value);

}

return value == null ? "" : value.toString();

} catch (Exception e) {

return "";

}

}

/**

* @return the datePattern

*/

public String getDatePattern() {

return datePattern;

}

/**

* @param pDatePattern the datePattern to set

*/

public void setDatePattern(String pDatePattern) {

datePattern = pDatePattern;

}

}

测试代码：

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JsonBean bean = new JsonBean();

bean.setName("NewBaby");

bean.setAge(1);

bean.setBorn(new Date());

JsonConfig jsonConfig = new JsonConfig();

jsonConfig.registerJsonValueProcessor(Date.class,new JsonDateValueProcessor());

JSONObject jo = JSONObject.fromObject(bean, jsonConfig);

System.out.println("bean->json:" + jo.toString());

打印结果：bean->json:{"age":1,"born":"2010-03-10","name":"NewBaby"}

这就能得到我们想要的结果了。

三、JSON-》java

1.如何把json的yyyy-MM-dd的转换为Bean中的util.Date类型：

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JSONUtils.getMorpherRegistry().registerMorpher(

new DateMorpher(new String[] { "yyyy-MM-dd" }));

String jsonStr = "[{\"name\": \"husband\", \"age\": \"26\", \"born\": \"1984-01-12\"},{\"name\": \"wife\", \"age\": \"20\", \"born\": \"1990-05-01\"}]";

Collection<JsonBean> list = JSONArray.toCollection(JSONArray.fromObject(jsonStr), JsonBean.class);

//DateUtil.getFormatDate(date,fmtstr)日期转字符串这里不再写代码了

for (JsonBean o : list) {

System.out.println(DateUtil.getFormatDate(o.getBorn(), "yyyy-MM-dd"));

}

打印结果：

1984-01-12

1990-05-01

2. JSON-》List、 Map

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String listStr = "[\"apple\",\"orange\"]";

Collection<String> strlist = JSONArray.toCollection(JSONArray.fromObject(listStr));

for (String str : strlist) {

System.out.println(str);

}

String mapStr = "{\"age\":30,\"name\":\"Michael\",\"baby\":[\"Lucy\",\"Lily\"]}";

Map<String, Object> map = (Map) JSONObject.toBean(JSONObject

.fromObject(mapStr), Map.class);

for (Entry<String, Object> entry : map.entrySet()) {

System.out.println(entry.getKey() + " " + entry.getValue());

}

打印结果：

apple

orange

name Michael

age 30

baby [Lucy, Lily]