实例：现在jsp页面传递一个名为username的参数到action中

url: http://localhost:8080/StudentSystem/role_list.action username=1321312

一、通过get set方法获取

在对应的action类中定义同名变量,并生成set get方法，那么参数将会自动获取值

String username;

public String getUsername()

{

return username;

}

public void setUsername(String username)

{

this.username = username;

}

System.out.println(username);//结果为1321312

二、通过ServletActionContext获取//导入import org.apache.struts2.ServletActionContext;

HttpServletRequest reqeust= ServletActionContext.getRequest();

String username=reqeust.getParameter("username");//字符串

//url: http://localhost:8080/StudentSystem/role_list.action username=1321312&username=34343

String[] username=reqeust.getParameterValues("username");//字符串数组

System.out.println(username);//结果为1321312

System.out.println(username[0]);//结果为1321312

三、通过ActionContext获取//导入import com.opensymphony.xwork2.ActionContext;

ActionContext context = ActionContext.getContext();

Map params = context.getParameters();

String[] username=(String[])params.get("username");

//ActionContext获取到一个对象如object或String[]

System.out.println(username[0]);//结果为1321312