source:
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
view plaincopy to clipboardprint?
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
view plaincopy to clipboardprint?
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
view plaincopy to clipboardprint?
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：
view plaincopy to clipboardprint?
/**
* 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：
view plaincopy to clipboardprint?
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：
view plaincopy to clipboardprint?
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
view plaincopy to clipboardprint?
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]