Jackson---此文章摘自jackson官网例子

易于人阅读和编写。同时也易于机器解析和生成

JSON-lib官网：http://json-lib.sourceforge.net/

Jackson官网：http://jackson.codehaus.org/

号称性能最快的JSON处理器Jackson远高于JSON_lib

转化json字符串：

/** * 使用Jackson生成json格式字符串 *  * @author archie2010 since 2011-4-26下午05:59:46 */public class JacksonTest {    private static JsonGenerator jsonGenerator = null;    private static ObjectMapper objectMapper = null;    private static User user = null;    /**     * 转化实体为json字符串     * @throws IOException     */    public static void writeEntity2Json() throws IOException{        System.out.println("使用JsonGenerator转化实体为json串-------------");        //writeObject可以转换java对象，eg:JavaBean/Map/List/Array等        jsonGenerator.writeObject(user);        System.out.println();        System.out.println("使用ObjectMapper-----------");        //writeValue具有和writeObject相同的功能        objectMapper.writeValue(System.out, user);    }    /**     * 转化Map为json字符串     * @throws JsonGenerationException     * @throws JsonMappingException     * @throws IOException     */    public static void writeMap2Json() throws JsonGenerationException, JsonMappingException, IOException{        System.out.println("转化Map为字符串--------");        Map<String, Object> map=new HashMap<String, Object>();        map.put("uname", user.getUname());        map.put("upwd", user.getUpwd());        map.put("USER", user);        objectMapper.writeValue(System.out, map);    }    /**     * 转化List为json字符串     * @throws IOException      * @throws JsonMappingException      * @throws JsonGenerationException      */    public static void writeList2Json() throws IOException{        List<User> userList=new ArrayList<User>();        userList.add(user);                User u=new User();        u.setUid(10);        u.setUname("archie");        u.setUpwd("123");        userList.add(u);        objectMapper.writeValue(System.out, userList);                                 objectMapper.writeValue(System.out, userList);    }    public static void main(String[] args) {        user = new User();        user.setUid(5);        user.setUname("tom");        user.setUpwd("123");        user.setNumber(3.44);        objectMapper = new ObjectMapper();        try {            jsonGenerator = objectMapper.getJsonFactory().createJsonGenerator(System.out, JsonEncoding.UTF8);            //writeEntity2Json();            //writeMap2Json();            writeList2Json();        } catch (IOException e) {            e.printStackTrace();        }    }}

[{"number":3.44,"uname":"tom","upwd":"123","uid":5},{"number":0.0,"uname":"archie","upwd":"123","uid":10}]

输出到浏览器端：

StringWriter writer = new StringWriter();ObjectMapper mapper = new ObjectMapper();  try {   mapper.writeValue(writer, hMap);  } catch (JsonGenerationException e) {   e.printStackTrace();  } catch (JsonMappingException e) {   e.printStackTrace();  } catch (IOException e) {   e.printStackTrace();  }response.setContentType("text/html;charset=UTF-8");PrintWriter out= response.getWriter();out.print(writer.toString());