将Java对象转换为Json

1.导入如下三个jar包

2.示例代码

@WebServlet("/demo")
public class DemoServlet extends HttpServlet {
	@Override
	protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		System.out.println("执行控制器");
		String name = req.getParameter("name");
		Users users = new Users();
		users.setId(1);
		users.setPassword("123");
		users.setUsername("张三");
		Users users1 = new Users();
		users1.setId(2);
		users1.setPassword("22");
		users1.setUsername("李四");
		
		List list = new ArrayList();
		list.add(users1);
		list.add(users);
		
		
		//创建能够将Java对象转换为Json格式的工具对象
		ObjectMapper mapper = new ObjectMapper();
		//将Java的List对象转换为Json数组对象
		String result1 = mapper.writeValueAsString(list);
		//将Java对象转化为Json格式
		String result2 = mapper.writeValueAsString(users);
		//设置响应格式
		resp.setContentType("application/json;charset=utf-8");
		PrintWriter out = resp.getWriter();
		//返回响应数据
		out.println(result1);
		out.println(result2);
		out.flush();
		out.close();
	}
}