需要三个jar包

jackson-annotations-2.5.3.jar
jackson-core-2.5.3.jar
jackson-databind-2.5.3.jar

返回值类型-对象

@RequestMapping("/test2.action")
@ResponseBody
public Userinfo test2()
{
	Userinfo u = new Userinfo();
	u.setName("jj");
	u.setSex("M");
	u.setAge(20);

	return u;
}

返回值类型-字符串

@RequestMapping("/test")
@ResponseBody
public String test()
{
	return "{\"result\":true}";
}