訪問web元素的四種方法（耦合，依賴注入）、（耦合，非依賴注入）、（非耦合，依賴注入）、（非耦合，非依賴注入）

耦合：可以得到HttpServletResponse，HttpServletRequest，HttpSession等類型對象。能直接操作到真正的web元素。

非耦合：得到的是由struts封裝好的Map類型,只能對范圍進行存取值操作。

依賴注入：對象由struts2從外部注入。Action類不需要關心對象是如何得到的。

非依賴注入：對象由Action類自己提供初始化。

耦合

　　非依賴注入

1 public class UserAction extends ActionSupport{ 2 //類型為真實的web元素:HttpServletResponse,HttpServletRequest等.. 3 private HttpServletResponse resp; 4 private HttpServletRequest req; 5 private HttpSession session; 6 private ServletContext app; 7 8 public String execute() throws IOException{ 9 req = ServletActionContext.getRequest(); //得到request 10 resp = ServletActionContext.getResponse(); //得到response 11 app = ServletActionContext.getServletContext(); //得到application 12 session = ServletActionContext.getRequest().getSession(); //得到session 13 //操作 14 req.setAttribute("req", "write req.."); //往request里存值 15 session.setAttribute("session", "write session"); //住session里存值 16 session.getAttribute("session"); //從session里取值 17 resp.getWriter(); //得到response的 PrintWriter 18 return "test"; 19 } 20 }

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　　依賴注入

1 //實現ServletRequestAware,ServletResponseAware接口 2 public class UserAction extends ActionSupport implements ServletRequestAware,ServletResponseAware{ 3 private HttpServletResponse resp; 4 private HttpServletRequest req; 5 private HttpSession session; 6 private ServletContext app; 7 8 public String execute() throws IOException{ 9 //操作 10 req.setAttribute("req", "write req.."); //往request里存值 11 session.setAttribute("session", "write session"); //住session里存值 12 session.getAttribute("session"); //從session里取值 13 resp.getWriter(); //得到response的 PrintWriter 14 return "test"; 15 } 16 17 //重寫setServletResponse方法，Response對象不需要自己得到，由struts2從外部注入 18 public void setServletResponse(HttpServletResponse resp) { 19 this.resp=resp; //得到response 20 } 21 //重寫setServletRequest方法，Request對象不需要自己得到，由struts2從外部注入 22 public void setServletRequest(HttpServletRequest req) { 23 this.req=req; //得到request 24 this.session = req.getSession(); //得到session 25 this.app = session.getServletContext(); //得到application 26 } 27 }

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非耦合

?　　非依賴注入

1 public class UserAction extends ActionSupport{ 2 //得到的是由struts封裝好的Map類型,只能對范圍進行存取值操作 3 private Map<String,Object> req; 4 private Map<String,Object> session; 5 private Map<String,Object> app; 6 7 public String execute() throws IOException{ 8 req= (Map<String,Object>)ActionContext.getContext().get("request"); //得到request 9 session = ActionContext.getContext().getSession(); //得到session 10 app = ActionContext.getContext().getApplication(); //得到application 11 //操作 12 req.put("req", "write req.."); //存值到request 13 session.put("session", "write session.."); //存值到session 14 app.put("app", "write application.."); //存值到application 15 session.get("session"); //從session存值 16 return "test"; 17 } 18 }

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　　依賴注入（推薦）

1 //實現RequestAware,SessionAware,ApplicationAware等接口 2 public class UserAction extends ActionSupport implements RequestAware,SessionAware,ApplicationAware{ 3 //得到的是由struts封裝好的Map類型,只能對范圍進行存取值操作 4 private Map<String,Object> req; 5 private Map<String,Object> session; 6 private Map<String,Object> app; 7 8 public String execute() throws IOException{ 9 //操作 10 req.put("req", "write req.."); //存值到request 11 session.put("session", "write session.."); //存值到session 12 app.put("app", "write application.."); //存值到application 13 session.get("session"); //從session存值 14 return "test"; 15 } 16 //得到application 17 public void setApplication(Map<String, Object> app) { 18 this.app=app; 19 } 20 //得到session 21 public void setSession(Map<String, Object> session) { 22 this.session=session; 23 } 24 //得到request 25 public void setRequest(Map<String, Object> req) { 26 this.req= req; 27 } 28 }

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轉載于:https://www.cnblogs.com/likailan/p/3334553.html

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