SpringMVC探究-----常用获取传递参数的方法

   1.@RequestParam

     @RequestParam 常用来映射请求参数，它有三个属性可以配置：

• value 值即请求参数的参数名
• required 该参数是否必须. 默认为 true
• defaultValue 请求参数的默认值

<a href="springmvc/testRequestParam?username=yyx&age=29">Test
        RequestParam</a>

@RequestMapping(value = "/testRequestParam")
    public String testRequestParam(@RequestParam(value = "username") String username,
            @RequestParam(value = "age", required = false, defaultValue = "0") int age) {
        // @RequestParam(value = "age", required = false) Integer age) {
        System.out.println("testRequestParam,username:" + username + ",age:" + age);
        return SUCCESS;
    }

    注意：Integer值可以为null,int存入时必须有值

   2.@PathVariable

     @PathVariable 可以来映射 URL 中的占位符到目标方法的参数中.体现restful风格

<a href="springmvc/testPathVariable/1">Test PathVariable</a>

@RequestMapping("/testPathVariable/{id}")
    public String testPathVariable(@PathVariable("id") Integer id) {
        System.out.println("testPathVariable:" + id);
        return SUCCESS;
    }

   3.HttpServletRequest

     HttpServletRequest的getParameter(参数String)方法获取请求中的参数

<a href="springmvc/testServletAPI?userName=Tom">Test ServletAPI</a>

@RequestMapping("/testServletAPI")
    public String testServletAPI(HttpServletRequest request)
            throws IOException {
        System.out.println(request.getParameter("userName"));
        return SUCCESS;
    }

     注意：参数名称必须和登陆页面的name="userName"相同

   4.直接把表单的参数写在Controller相应的方法的形参中

<form action="${pageContext.request.contextPath}/springmvc/login"
        method="post">
        <table>
            <tr>
                <td>用户名:</td>
                <td><input type="text" name="userName"></td>
            </tr>
            <tr>
                <td>密码:</td>
                <td><input type="password" name="userPwd"></td>
            </tr>
            <tr>
                <td colspan="2"><input type="submit" value="登陆"></td>
            </tr>
        </table>
    </form>

/**
     * 控制器中方法的形参userName，userPwd
     * 名称必须和登陆页面的name="userName"，name="userPwd"相同
     * @param userName
     * @param userPwd
     * @return
     */
    @RequestMapping("/login")
    public String loginByUser(String userName, String userPwd) {
        System.out.println("userName is:" + userName);
        System.out.println("userPwd is:" + userPwd);
        return "success";
    }

  注意： name="userName"和String userName要一一对应，名称相同

   5.通过一个bean来接收

package com.springmvc.entity;

public class User {
    private String userName;
    private String userPwd;

    public User() {
        super();
    }

    public User(String userName, String userPwd) {
        super();
        this.userName = userName;
        this.userPwd = userPwd;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getUserPwd() {
        return userPwd;
    }

    public void setUserPwd(String userPwd) {
        this.userPwd = userPwd;
    }

    @Override
    public String toString() {
        return "User [userName=" + userName + ", userPwd=" + userPwd + "]";
    }

}

<form action="${pageContext.request.contextPath}/springmvc/loginPoJo"
        method="post">
        <table>
            <tr>
                <td>用户名:</td>
                <td><input type="text" name="userName"></td>
            </tr>
            <tr>
                <td>密码:</td>
                <td><input type="password" name="userPwd"></td>
            </tr>
            <tr>
                <td colspan="2"><input type="submit" value="登陆"></td>
            </tr>
        </table>
    </form>

/**
     *  登陆页面的name="userName"，name="userPwd"必须和Bean类的属性名称相同
     * @param user
     * @return
     */
    @RequestMapping("/loginPoJo")
    public String loginByUser(User user) {
        System.out.println("userName is:" + user.getUserName());
        System.out.println("userPwd is:" + user.getUserPwd());
        return "success";
    }

   注意： name="userName"和PoJo属性要一一对应，名称相同