json字符串构造为对象

在郑州大学参加校招的时候，遇到了一家看着貌似不错的公司，公司boss本身就是程序员出身，所以笔试题也是比较别致的。。。。我拿到卷子一看，就一道题目。

将json字符串构造成对象，当时实在是没有想到怎么实现的，因此而错过了一个比较好的机会，从那以后对这道题目印象十分深刻，今天看到一种方法，不知道是否符合当时的笔试要求。方法如下：

所需jar包：

jackson-core-asl-1.8.5.jar,jackson-mapper-asl-1.8.5.jar  ，

实现类：

import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.util.Date;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.JsonParser.Feature;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

import com.weqia.site.task.form.TaskForm;

public class JsonUtil {
	private static final Log log = LogFactory.getLog(JsonUtil.class);

	/**
	 * 
	 * @Description 把object转换成JSON格式的字符串
	 * @param obj
	 * @return
	 */
	public static String toJson(Object obj) {
		Writer writer = new StringWriter();
		String result = "";
		try {
			
			ObjectMapper om = new ObjectMapper(); 
			om.writeValue(writer, obj);
			result = writer.toString();
			if (log.isDebugEnabled()) {
				System.out.println(result);
			}
		} catch (Exception e) {
			if (log.isDebugEnabled()) {
				log.debug(e.getMessage(), e);
			}
		} finally {
			if(writer != null){
				try {
					writer.close();
					writer = null;
				} catch (IOException e) {
					if (log.isDebugEnabled()) {
						log.debug(e.getMessage(), e);
					}
				}
			}
		}
		
		return result;
	}
	
	/**
	 * 把JSON格式的字符串转换成对应的对象实例
	 * @param json
	 * @param clas
	 * @return
	 */
	public static <T> T toObject(String json, Class<T> clas){
		T obj = null;
		try {
			ObjectMapper om = new ObjectMapper();
			om.configure(Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true) ;
			obj = om.readValue(json, clas);
		} catch (JsonParseException e) {
			log.error(e.getMessage(), e);
		} catch (JsonMappingException e) {
			log.error(e.getMessage(), e);
		} catch (IOException e) {
			log.error(e.getMessage(), e);
		}
		
		return obj;
	}
	
	/**
	 * 把JSON格式的字符串转换成对应的对象实例  不显示异常
	 * @param json
	 * @param clas
	 * @return
	 */
	public static <T> T toObjectHide(String json, Class<T> clas){
		T obj = null;
		try {
			ObjectMapper om = new ObjectMapper();
			om.configure(Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true) ;
			obj = om.readValue(json, clas);
		} catch (JsonParseException e) {
			
		} catch (JsonMappingException e) {
			
		} catch (IOException e) {
			
		}
		
		return obj;
	}
	
	public static void main(String[] args){
	   TaskForm tasks = new TaskForm(); 
	   String[] member_ids = new String[0];		
	   Integer[] fileIds = new Integer[0];
	
	   tasks.setMember_ids(member_ids);
	   tasks.setFileIds(fileIds);
	   tasks.setBegin_date(new Date());
	   
	   String sss=  JsonUtil.toJson(tasks);
	   
	   // {"task_id":null,"member_id":null,"company_id":null,"project_id":null,"task_title":null,"begin_date":null,"visible_type":null,"task_content":null,"member_ids":[],"sourceType":null,"isProjectTask":false,"is_sms":null,"end_date":null,"create_id":null,"fileIds":[],"modify_id":null}
	   //System.out.println(sss);
	   
	   tasks.setMember_ids(null);
	   tasks.setFileIds(null);
	   tasks.setBegin_date(new Date(-1));
	   String sss1=  JsonUtil.toJson(tasks);
	   //System.out.println(sss1);
	   
	}
}

只是不太确定当时笔试要求是否是不让调用jar包的，如果是，还是不合格的，以后真的要多看一些源码了