Json_jackson_me

处理json格式数据的几大框架对比 ： http://wangym.iteye.com/blog/738933

jackson-all-1.7.4.jar 包下载：http://pan.baidu.com/s/1g6bQe

先将ObjectMapper封装成单例（实际应用中建议这么用）

package com.json.util;import org.codehaus.jackson.map.ObjectMapper;public class JacksonMapper{    /**      *       */      private static final ObjectMapper mapper = new ObjectMapper();      /**      *       */      private JacksonMapper() {      }      /**      *       * @return      */      public static ObjectMapper getInstance() {          return mapper;      }  }

pojo/bean/entity
AccountBean ：

package com.json.bean;import java.io.Serializable;public class AccountBean implements Serializable{    /**     * serialVersionUID     */    private static final long serialVersionUID = 7313637781426247547L;    private int id;    private String name;    private String email;    private String address;    private Birthday birthday;    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;    }    public String getEmail()    {        return email;    }    public void setEmail(String email)    {        this.email = email;    }    public String getAddress()    {        return address;    }    public void setAddress(String address)    {        this.address = address;    }    public Birthday getBirthday()    {        return birthday;    }    public void setBirthday(Birthday birthday)    {        this.birthday = birthday;    }    public AccountBean()    {    }    public AccountBean(int id, String name, String email, String address, Birthday birthday)    {        super();        this.id = id;        this.name = name;        this.email = email;        this.address = address;        this.birthday = birthday;    }    @Override    public String toString()    {        return this.name + "#" + this.id + "#" + this.address + "#" + this.birthday + "#" + this.email;    }}

Birthday ：

package com.json.bean;import java.io.Serializable;public class Birthday implements Serializable{    /**     * serialVersionUID     */    private static final long serialVersionUID = 1L;    private String birthday;    public String getBirthday()    {        return birthday;    }    public void setBirthday(String birthday)    {        this.birthday = birthday;    }    public Birthday()    {    }    public Birthday(String birthday)    {        this.birthday=birthday;    }    @Override    public String toString()    {        return this.birthday;    }}

测试

public class Test_me{    private ObjectMapper objectMapper = JacksonMapper.getInstance();    private AccountBean bean = new AccountBean(23, "jack", "[e-mail]", "shanghai", new Birthday("19901101"));/* 1、JavaBean(Entity/Model)与JSON字符串的互转 */    /**    *   将bean转换成json    */public String writeEntityJSON()    {        try        {            String str = objectMapper.writeValueAsString(bean);            System.out.println(str);            return str;        }        catch (IOException e)        {            e.printStackTrace();        }        return null;    }    /**    *   将json格式数据转换成bean    */   public void readJson2Entity()    {        String json = "{\"address\":\"address\",\"name\":\"haha\",\"id\":1,\"email\":\"email\"}";        try        {            AccountBean ab= objectMapper.readValue(json, AccountBean.class);            System.out.println(ab.getName());            System.out.println(ab);        }        catch (Exception e)        {            e.printStackTrace();        }    }/* 2、Map集合与Json字符串互转 */    /**    *   将Map格式数据转换成Json格式    */ public void writeMapJSON()    {        try        {            Map<String, Object> map = new HashMap<String, Object>();            map.put("response", true);            map.put("bean1", bean);            map.put("bean2", bean);            System.out.println(objectMapper.writeValueAsString(map));        }        catch (Exception e)        {            e.printStackTrace();        }    }    /**    *   将json格式数据转换成Map    */ public void readJson2Map()    {        String json =            "{\"success\":true,\"bean2\":{\"address\": \"address2\",\"name\":\"haha2\",\"id\":2,\"email\":\"email2\"}," + "\"bean1\":{\"address\":\"address\",\"name\":\"haha\",\"id\":1,\"email\":\"email\"}}";        System.out.println("---------------------------------readJson2Map---------------------------------------");        try        {            Map<String, Map<String, Object>> maps = objectMapper.readValue(json, Map.class);            System.out.println(maps.size());            Set<String> key = maps.keySet();            Iterator<String> iter = key.iterator();            while (iter.hasNext())            {                String field = iter.next();                System.out.println(field + ":" + maps.get(field));            }        }        catch (Exception e)        {            e.printStackTrace();        }    }/* 3、List集合与Json字符串互转 */    /**    *   将List格式数据转换成Json格式    */public void writeListJSON()    {        try        {            List<AccountBean> list = new ArrayList<AccountBean>();            list.add(bean);            bean = new AccountBean(22, "tom", "[e-mail]", "shanghai", new Birthday("19930515"));            list.add(bean);            System.out.println("1###" + objectMapper.writeValueAsString(list));        }        catch (IOException e)        {            e.printStackTrace();        }    }    /**    *   将Json格式数据转换成List格式    */ public void readJson2List_me()    {        String json = "[{\"uid\":1,\"uname\":\"www\",\"number\":234,\"upwd\":\"456\"}," + "{\"uid\":5,\"uname\":\"tom\",\"number\":3.44,\"upwd\":\"123\"}]";        /*         * Exception in thread "main" java.lang.ClassCastException: java.util.LinkedHashMap cannot be cast to com.json.bean.User         * So I had to use  java.util.LinkedHashMap.         */        try        {            List<LinkedHashMap<String, Object>> list = objectMapper.readValue(json, List.class);            System.out.println(list.size());            for (int i = 0; i < list.size(); i++)            {                Map<String, Object> map = list.get(i);                Set<String> set = map.keySet();                for (Iterator<String> it = set.iterator(); it.hasNext();)                {                    String key = it.next();                    System.out.println(key + ":" + map.get(key));                }            }        }        catch (Exception e)        {            e.printStackTrace();        }    }/* 4、Array与Json字符串互转 */    /**    *   将Array转换成Json格式    */    public  void Array2Json()    {        AccountBean[] arr=new AccountBean[2];        arr[0]=bean;        bean.setId(21);        arr[1]=bean;        try        {           String str= objectMapper.writeValueAsString(arr);           System.out.println(str);        }        catch (Exception e)        {            e.printStackTrace();        }    }    /**    *   将Json格式转换成Array    */ public void readJson2Array()    {        String json = "[{\"address\": \"address2\",\"name\":\"haha2\",\"id\":2,\"email\":\"email2\"}," + "{\"address\":\"address\",\"name\":\"haha\",\"id\":1,\"email\":\"email\"}]";        try        {            AccountBean[] arr = objectMapper.readValue(json, AccountBean[].class);            System.out.println(arr.length);            for (int i = 0; i < arr.length; i++)            {                AccountBean ab = arr[i];                System.out.println(ab.getAddress());                System.out.println(ab.getId());                System.out.println(ab.getName());            }        }        catch (Exception e)        {            e.printStackTrace();        }    }

关于JsonGenerator以及jackson的更多用法参见相关文档。