Spring Redirect 及 ModelAttribute

最新推荐文章于 2022-07-14 14:38:14 发布

斯温jack

最新推荐文章于 2022-07-14 14:38:14 发布

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分类专栏：网络编程 Spring 文章标签： Spring redirect ModelAttribute addFlashAttribute 表单对象绑定

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本文代码转载自
《Servlet、JSP和Spring MVC初学指南》

Spring 自定义重定向仅需要在 Controller 用相应的request处理方法中将

return 中对要从定向的链接加redirect前缀

在重定向的同时一般需要进行重定向传值如像从定向之后的

controller的某处理函数添加 attribute 用于后续页面渲染等操作

这可以借用

RedirectAttributes.addFlashAttribute

完成

下面是一个重定向 并进行传值的简单实例

用于数据绑定的Bean

package domain;
import java.io.Serializable;

public class Product implements Serializable {
    private static final long serialVersionUID = 5784L;
	private long id;
	private String name;
    private String description;
    private float price;

    public long getId() {
		return id;
	}
	public void setId(long id) {
		this.id = id;
	}
    public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }
    public float getPrice() {
        return price;
    }
    public void setPrice(float price) {
        this.price = price;
    }
}

package form;

public class ProductForm {
    private String name;
    private String description;
    private String price;

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }
    public String getPrice() {
        return price;
    }
    public void setPrice(String price) {
        this.price = price;
    }
}

逻辑处理 简单接口

package service;

/**
 * Created by admin on 2017/3/1.
 */

import domain.Product;

public interface ProductService {
    Product add(Product product);
    Product get(long id);
}

package service;

/**
 * Created by admin on 2017/3/1.
 */

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicLong;

import org.springframework.stereotype.Service;

import domain.Product;

@Service
public class ProductServiceImpl implements ProductService {

    private Map<Long, Product> products = new HashMap<>();
    private AtomicLong generator = new AtomicLong();

    public ProductServiceImpl(){
        Product product = new Product();
        product.setName("JX1 Power Drill");
        product.setDescription("Powerful hand drill, made to perfection");
        product.setPrice(129.99F);
        add(product);
    }

    @Override
    public Product add(Product product){
        long newId = generator.incrementAndGet();
        product.setId(newId);
        products.put(newId, product);

        return product;
    }

    @Override
    public Product get(long id){
        return products.get(id);
    }

}

ProductForm.jsp

<%--
  Created by IntelliJ IDEA.
  User: admin
  Date: 2017/3/1
  Time: 9:23
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Add Product Form</title>
    <style type="text/css">@import url("/css/main.css");</style>
</head>
<body>
<div id = "global">
    <form action = "/product_save" method="post">
        <fieldset>
            <legend>Add a product</legend>
            <p>
                <label for = "name">Product Name </label>
                <input type = "text" id = "name" name = "name" tabindex="1">
            </p>
            <p>
                <label for = "description">Description:</label>
                <input type="text" id = "description" name = "description" tabindex="2">
            </p>
            <p>
                <label for = "price">Price:</label>
                <input type = "text" id = "price" name = "price" tabindex="3">
            </p>
            <p id = "buttons">
                <input type="reset" id = "reset" tabindex="4">
                <input type = "submit" tabindex="5" value="Add Product">
            </p>
        </fieldset>

    </form>

</div>

</body>
</html>

ProductView.jsp

<%--
  Created by IntelliJ IDEA.
  User: admin
  Date: 2017/3/1
  Time: 9:30
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>View Product</title>
    <style type="text/css">@import url(/css/main.css);</style>
</head>
<body>
<div id = "global">
    <h4>${message}</h4>
    <p>
    <h5>Details:</h5>
        Product Name: ${product.name}<br/>
        Description: ${product.description}<br/>
        Price: ${product.price}

    </p>
</div>

</body>
</html>
Controller类
package controller;

/**
 * Created by admin on 2017/3/1.
 */
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

import domain.Product;
import form.ProductForm;
import service.ProductService;

@Controller
public class ProductController {
    private static final Log logger = LogFactory.getLog(ProductController.class);

    @Autowired
    private ProductService productService;

    @RequestMapping(value = "/product_input")
    public String inputProduct(){
        logger.info("inputProduct called");
        return "ProductForm";
    }

    @RequestMapping(value = "/product_save", method = RequestMethod.POST)
    public String saveProduct(ProductForm productForm, RedirectAttributes redirectAttributes){
        logger.info("saveProduct called");

        Product product = new Product();
        product.setName(productForm.getName());
        product.setDescription(productForm.getDescription());
        try{
            product.setPrice(Float.parseFloat(productForm.getPrice()));
        }catch(NumberFormatException e){

        }

        Product savedProduct = productService.add(product);
        redirectAttributes.addFlashAttribute("message","The product was successfully added.");

        return "redirect:/product_view/" + savedProduct.getId();
    }

    @RequestMapping(value = "/product_view/{id}")
    public String viewProduct(@PathVariable Long id, Model model){
        Product product = productService.get(id);
        model.addAttribute("product", product);

        return "ProductView";
    }

}



配置文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/applicationContext.xml</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>

        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/config/dispatcher-config.xml</param-value>
        </init-param>

    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">

    <context:component-scan base-package="controller"/>
    <context:component-scan base-package="service"/>

    <mvc:resources mapping="/css/**" location="css/"/>
    <mvc:resources mapping="/*.html" location="/"/>

    <mvc:annotation-driven/>

    <bean id = "viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name = "prefix" value="/WEB-INF/jsp/"/>
        <property name = "suffix" value=".jsp"/>
    </bean>


</beans>

进行页面表单提交后 会发现 message 作为（重定向）attribute 被渲染出来

在一般进行Model处理的过程中 有时需要进行预处理

这可以借用ModelAttribute

被其声明的方法 会在controller进行具体页面处理的逻辑调用之前进行调用

将某个类设定为attribute

下面是一个简单例子

表单jsp

<%--
  Created by IntelliJ IDEA.
  User: admin
  Date: 2017/3/1
  Time: 9:23
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Add Product Form</title>
    <style type="text/css">@import url("/css/main.css");</style>
</head>
<body>
<div id = "global">
    <form action = "/employee_save" method="post">
        <input type="hidden" name="number" value="1">
        <fieldset>
            <legend>Add a product</legend>
            <p>
                <label for = "name">Product Name </label>
                <input type = "text" id = "name" name = "name" tabindex="1">
            </p>
            <p>
                <label for = "description">Description:</label>
                <input type="text" id = "description" name = "description" tabindex="2">
            </p>
            <p>
                <label for = "price">Price:</label>
                <input type = "text" id = "price" name = "price" tabindex="3">
            </p>
            <p id = "buttons">
                <input type="reset" id = "reset" tabindex="4">
                <input type = "submit" tabindex="5" value="Add Product">
            </p>
        </fieldset>

    </form>

</div>

</body>
</html>

展示jsp

<%--
  Created by IntelliJ IDEA.
  User: admin
  Date: 2017/3/1
  Time: 9:20
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Save Product</title>
    <style type="text/css">@import url(/css/main.css);</style>
</head>
<body>

    <div id = "global">
        <h4>The product has been saved.</h4>
        <p>
        <h5>Details:</h5>
        Product Name: ${product.name}<br/>
        Description: ${product.description}<br/>
        Price: ${product.price}
        </p>
    </div>

</body>
</html>

Controller类

package controller;

/**
 * Created by admin on 2017/3/1.
 */

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.stereotype.Controller;

import domain.Product;
@Controller
public class EmployeeController {
    private static final Log logger = LogFactory.getLog(EmployeeController.class);

    @RequestMapping(value = "/employee_input")
    public String inputEmployee(){
        logger.info("inputEmployee called");
        return "ProductForm";
    }

    @RequestMapping(value = "/employee_save")
    public String saveEmployee(Product product, BindingResult bindingResult, Model model){
        logger.info("saveEmployee called");
        logger.info("as map :" + model.asMap());
        logger.info("The number id :" + product.getId());

        if(bindingResult.hasErrors()){
            logger.info("has errors");
            FieldError fieldError = bindingResult.getFieldError();
            logger.info("Code:" + fieldError.getCode() + ", field:" + fieldError.getField() );

            return "ProductForm";
        }

        model.addAttribute("product", product);
        return "ProductDetails";

    }


    @ModelAttribute
    public Product addAccount(@RequestParam String number){
        logger.info("addAccount called number is " + number);
        Product product = new Product();
        product.setName("ana");
        product.setId(1000000);
        return  product;
    }


    @ModelAttribute
    public void populateModel(@RequestParam String number, Model model){
        logger.info("populateModel called. number is " + number);
        model.addAttribute("blah");
    }


}

Spring 为表单对象实现了自动绑定 该绑定 仅仅是对于Field的 对相应的类名

等并没有具体要求 甚至允许绑定的类 的 Field比表单的Field多

（这里以Id为例）

在addAccount方法中 可以对传输到具体处理逻辑的对象product进行预处理

其结果是 设定未设定的对象 如Id 但是对于表单传输的对象 不进行修改

如当输入name不是ana时 仍然显示出输入name

当然 ModelAttribute还可以用于修饰 controller的方法 其基本作用是当整个模型

不存在此名称的attribute时调用相应的类构造函数初始化相应的javaBean类

当存在此名称的attribute时与一般的类参数相同 用于表单对象绑定。

相应较为细致的论述见

http://www.cnblogs.com/shucunbin/p/4438711.html