【业务功能篇50】ObjectMapper-将java对象转为json字符串

ObjectMapper可以实现Java对象和json字符串间互相转换，我们经常用到的是它的Java对象转json字符串功能。这里目的是

Java对象 json字符串相互转换 api

【json字符串转为Java对象：readValue(json字符串,类.class)】
【Java对象转为json字符串：writeValueAsString(class类对象)】

package test;
import java.io.IOException;
import java.util.*;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
public class UserData {
    public static void main(String[] args) throws JsonGenerationException, JsonMappingException, IOException{
        ObjectMapper objectMapper = new ObjectMapper();
        User u = new User();
        u.setName("Lucy");
        u.setAge(10);
        u.setSex("woman");
        //对象转为json字符串
        String userJson = objectMapper.writeValueAsString(u);
        System.out.println("对象转为json字符串:");
        System.out.println(userJson);
        //json字符串转为对象
        String UserString = "{\"name\":\"Lily\", \"age\":9, \"sex\":\"woman\"}";
        User u2 = objectMapper.readValue(UserString,User.class);
        System.out.println("json字符串转为对象:");
        System.out.println(u2);
    }
}