json-lib date对象转json ，加入自定义日期格式处理

import net.sf.json.JSONObject;
import net.sf.json.JsonConfig;
import net.sf.json.processors.JsonValueProcessor;

public class DateJsonValueProcessor implements JsonValueProcessor {
public static final String DEFAULT_DATE_PATTERN = "yyyy-MM-dd HH:mm:ss";
private DateFormat dateFormat;

/**
* 构造方法.
*
* @param datePattern 日期格式
*/
public DateJsonValueProcessor(String datePattern) {
try {
dateFormat = new SimpleDateFormat(datePattern);
} catch (Exception ex) {
dateFormat = new SimpleDateFormat(DEFAULT_DATE_PATTERN);
}
}

public Object processArrayValue(Object value, JsonConfig jsonConfig) {
return process(value);
}

public Object processObjectValue(String key, Object value,
JsonConfig jsonConfig) {
return process(value);
}

private Object process(Object value) {
if (value == null) {
value = new Date();   //为null时返回当前日期，也可以返回"",看需要
}
return dateFormat.format((Date) value);
}

public static String map2JSonStr(Map map) {
JsonConfig jsonConfig = new JsonConfig();
DateJsonValueProcessor beanProcessor = new DateJsonValueProcessor(
DEFAULT_DATE_PATTERN);
jsonConfig.registerJsonValueProcessor(Date.class, beanProcessor);

JSONObject jsonObject = JSONObject.fromObject(map, jsonConfig);

return jsonObject.toString();
}

//将对象转换为json string，使用上面定义的的日期格式
@SuppressWarnings("unchecked")
public static JSONObject obj2JsonObj(Object obj) {
JsonConfig jsonConfig = new JsonConfig();
DateJsonValueProcessor beanProcessor = new DateJsonValueProcessor(
DEFAULT_DATE_PATTERN);
jsonConfig.registerJsonValueProcessor(Date.class, beanProcessor);

JSONObject jsonObject = JSONObject.fromObject(obj, jsonConfig);

return jsonObject;
}
}