Java Spring MVC 在同一个 JSP 中获取/发布
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Java Spring MVC get/post in same JSP
提问by Jaanus
this is from my controller..
这是来自我的控制器..
@RequestMapping(value = "/add", method = RequestMethod.GET)
public String add(Model model) {
return "add";
}
@RequestMapping(value = "/add", method = RequestMethod.POST)
public String added(@RequestParam("name") String name, Model model) {
City city = new City();
city.setCity(name);
service.addCity(city);
return "add";
}
this is my JSP view..this is only for adding at the moment...this is add.jsp..so it posts back to itself
这是我的 JSP 视图..这仅用于目前添加......这是 add.jsp..所以它回传给自己
<form method="post" action="/spring/krams/edit/add">
Linna nimi
<input type="text" name="name">
<input type="submit" value="Test" name="submit" />
</form>
i would like the JSP file change , so that when i post it to this file, then it says..."CITY ADDED" . is that possible?
我想更改 JSP 文件，以便当我将其发布到此文件时，它会显示...“添加了城市”。那可能吗？
WHAT ABOUT UPDATING A CITY??
更新一个城市怎么样？？
@RequestMapping(value = "/update", method = RequestMethod.POST)
public String updated(@RequestParam("city") int city_id,
@RequestParam("text") String name,
Model model) {
service.updateCity(name, city_id);
return "update";
}
Here is no object?
这里没有对象？
回答by Javi
In the post method you can add an attribute with addAttribute method
在 post 方法中，您可以使用 addAttribute 方法添加属性
@RequestMapping(value = "/add", method = RequestMethod.POST)
public String added(@RequestParam("name") String name, Model model) {
City city = new City();
city.setCity(name);
service.addCity(city);
model.addAttribute("city", city);
return "add";
}
and in the JSP you can check if the attribute city is null or not (with the tag <c:if/>). In case it is not null, it is because it has just been added to the model, so you can show whatever you want. ${city.city}its just a JSTL expression which accesses to the city attribute and then call the getter to access to the city property of that attribute:
并且在 JSP 中，您可以检查属性 city 是否为空（使用标记<c:if/>）。如果它不为空，那是因为它刚刚添加到模型中，因此您可以显示任何您想要的内容。${city.city}它只是一个 JSTL 表达式，它访问 city 属性，然后调用 getter 来访问该属性的 city 属性：
<%@ taglib uri="http://java.sun.com/jstl/core_rt" prefix="c" %>
<c:if test="${city != null}">
CITY <c:out value="${city.city}" /> ADDED
</c:if>
UPDATE
更新
If you need different messages depending on update/create operations you can do this: (In the example an update is done when the id param is not null because the id is the identifier of the city to update)
如果根据更新/创建操作需要不同的消息，您可以执行以下操作：（在示例中，当 id 参数不为 null 时完成更新，因为 id 是要更新的城市的标识符）
@RequestMapping(value = "/add", method = RequestMethod.POST)
public String added(@RequestParam(value="id", required=false) String id, @RequestParam("name") String name, Model model) {
City city;
String operation;
if(id== null){
//create operation
city = new City();
operation = "CREATE";
}else{
//update operation
city = service.findCity(id);
operation = "UPDATE";
}
city.setCity(name);
service.saveCity(city); //save or update
model.addAttribute("city", city);
model.addAttribute("operation", operation); //add operation param
return "add";
}
and in the JSP you can do:
在 JSP 中，您可以执行以下操作：
<%@ taglib uri="http://java.sun.com/jstl/core_rt" prefix="c" %>
<c:if test="${operation == 'CREATE'}">
<c:if test="${city != null}">
CITY <c:out value="${city.city}" /> ADDED
</c:if>
<c:if test="${operation == 'UPDATE'}">
CITY <c:out value="${city.city}" /> UPDATED
</c:if>
</c:if>
