在解析JSON方面，无疑JACKSON是做的最好的，下面从几个方面简单复习下。

1 JAVA 对象转为JSON
  import java.io.File; import java.io.IOException; import org.codehaus.jackson.JsonGenerationException; import org.codehaus.jackson.map.JsonMappingException; import org.codehaus.jackson.map.ObjectMapper; public class JacksonExample { public static void main(String[] args) { User user = new User(); ObjectMapper mapper = new ObjectMapper(); try { // convert user object to json string, and save to a file mapper.writeValue(new File("c:\\user.json"), user); // display to console System.out.println(mapper.writeValueAsString(user)); } catch (JsonGenerationException e) { e.printStackTrace(); } catch (JsonMappingException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } }

输出为：
{"age":29,"messages":["msg 1","msg 2","msg 3"],"name":"mkyong"}


2 JSON反序列化为JAVA对象
   import java.io.File; import java.io.IOException; import org.codehaus.jackson.JsonGenerationException; import org.codehaus.jackson.map.JsonMappingException; import org.codehaus.jackson.map.ObjectMapper; public class JacksonExample { public static void main(String[] args) { ObjectMapper mapper = new ObjectMapper(); try { // read from file, convert it to user class User user = mapper.readValue(new File("c:\\user.json"), User.class); // display to console System.out.println(user); } catch (JsonGenerationException e) { e.printStackTrace(); } catch (JsonMappingException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } }
输出：User [age=29, name=mkyong, messages=[msg 1, msg 2, msg 3]]

3 在上面的例子中，如果要输出的JSON好看点，还是有办法的，就是使用
defaultPrettyPrintingWriter()方法，例子为：
User user = new User(); ObjectMapper mapper = new ObjectMapper(); System.out.println(mapper.defaultPrettyPrintingWriter().writeValueAsString(user));

则输出整齐：
{
  "age" : 29,
  "messages" : [ "msg 1", "msg 2", "msg 3" ],
  "name" : "mkyong"
}