package cn.hopetesting.com.test;import cn.hopetesting.com.domain.User;import com.fasterxml.jackson.core.JsonProcessingException;import com.fasterxml.jackson.databind.ObjectMapper;import org.junit.Test;import java.io.File;import java.io.FileWriter;import java.io.IOException;/** * @author newcityman * @date 2019/9/17 - 23:12 步骤1、导入jackson的三个包 2、创建一个user对象，并赋值 3、创建jackson的核心对象ObjectMapper 4、调用ObjectMapper的writevalue等相关方法 */public class TestJson {@Test public void test1() throws IOException {//1、创建对象 User user = new User("zmy",20,"male"); //2、创建jackson的核心对象 ObjectMapper ObjectMapper mapper = new ObjectMapper(); //3、转换 /*try { String json = mapper.writeValueAsString(user); System.out.println(json); } catch (JsonProcessingException e) { e.printStackTrace(); }*/ //将数据写到d://a.txt文件中// mapper.writeValue(new File("d://a.txt"),user); //将数据关联到writer中 mapper.writeValue(new FileWriter("d://b.txt"),user); }@Test public void test2() throws IOException {//1、创建对象 User user = new User("zmy",20,"male"); user.setBirthday(new Date()); //2、创建jackson的核心对象 ObjectMapper ObjectMapper mapper = new ObjectMapper(); String json = mapper.writeValueAsString(user); System.out.println(json); }@Test public void test3() throws IOException {//1、创建user和list对象 User user = new User("zmy",20,"male",new Date()); User user1 = new User("light",10,"male",new Date()); User user2 = new User("cityboy",5,"male",new Date()); List<User> ps = new ArrayList<User>(); ps.add(user); ps.add(user1); ps.add(user2); //2、创建jackson的核心对象 ObjectMapper ObjectMapper mapper = new ObjectMapper(); String json = mapper.writeValueAsString(ps); System.out.println(json); }@Test public void test4() throws IOException { Map<String,Object> map = new HashMap<String, Object>(); map.put("name","zmy"); map.put("age",15); map.put("gender","男"); ObjectMapper mapper = new ObjectMapper(); String json = mapper.writeValueAsString(map); System.out.println(json); }//演示 json字符串转换为java对象 @Test public void test5() throws IOException {//初始化json字符串 String json="{\"gender\":\"男\",\"name\":\"zmy\",\"age\":15}"; //创建ObjectMapper对象 ObjectMapper mapper = new ObjectMapper(); //转换json字符串为java对象 User user = mapper.readValue(json, User.class); System.out.println(user); }}
转载于:https://www.cnblogs.com/newcityboy/p/11538020.html
相关资源：Java对象与Json之间的互相转换的jar包
