SpringMVC入门学习三

@RequestMapping("/test")
public String test(@ModelAttribute("name")String name){
    // 输出是  名字是Tom
    System.out.println("名字是"+name);
    return "test";
}

@RequestMapping("/test2")
public String test2(@SessionAttribute("name") String name){
    System.out.println("session结果是"+name);
    return "test";
}

@RequestMapping("/test2")
    //非必须，同时value/name必须加上
    public String test2(@SessionAttribute(value = "name",required = false) String name){
        System.out.println("session结果是"+name);
        return "test";
    }

@RequestMapping("/test3")
public String test3(@RequestParam(value = "name",defaultValue = "TomCat") String name){
    // 请求网址是： /test3
    // 输出是  名字是TomCat
    System.out.println("名字是"+name);
    return "test";
}

<!--====>jackson包导入start-->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.9.7</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.9.7</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-annotations</artifactId>
    <version>2.9.7</version>
</dependency>
<!--====>jackson包导入end-->

$(document).ready(function () {
    $("button").click(function () {
        $.ajax({
            url: "/test4",
            type:"post",
            data:JSON.stringify({
                "name":"TODO"
            }),
            dataType:"json",
            contentType:"application/json; charset=utf-8",
            success:function (data) {
                console.log(data)
            }
        });
    });
});

@RequestMapping("/test4")
public String test4(@RequestBody String name){
    // 名字是{"name":"TOFO"}
    System.out.println("名字是"+name);
    return "test";
}

@RequestMapping(value = "/test4")
@ResponseBody
public User test4(@RequestBody String name){
    // 名字是{"name":"TOFO"}
    System.out.println("名字是"+name);
    User u = new User();
    u.setName("小明");
    u.setAge("17");
    return u;
}

<dependency>
    <groupId>com.fasterxml.jackson.dataformat</groupId>
    <artifactId>jackson-dataformat-xml</artifactId>
    <version>2.9.7</version>
</dependency>

// 由于要返回xml格式的数据，所以需要设置produces为application/xml
// 使用MediaType里面的静态常量,可以防止写错
@ResponseBody
@RequestMapping(value = "/test5",produces = org.springframework.http.MediaType.APPLICATION_XML_VALUE)
public User test5(){
    User u = new User();
    u.setName("小红");
    u.setAge("18");
    return u;
}

<!-- 装成自己是post请求 -->
<form action="/put" method="post">
    <!-- 实际上想发送的PUT请求 -->
    <input type="hidden" name="_method" value="PUT">
    姓名 <input  name="name" type="text">
    <input type="submit" value="提交">
</form>

<filter>
    <!-- 原理就是从_method找到真正想要http请求，然后分发给controller 
         所以这个必须写在DispatcherServlet的前面
    -->
    <filter-name>HiddenHttpMethodFilter</filter-name>
    <filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>HiddenHttpMethodFilter</filter-name>
    <servlet-name>springmvc</servlet-name>
</filter-mapping>

<!--注册一个前端控制器-->
<servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <!--上下文配置的位置的制定-->
        <param-name>contextConfigLocation</param-name>
        <!--此时是在类路径下面去寻找-->
        <param-value>classpath:springmvc.xml</param-value>
    </init-param>
</servlet>

<!--servlet的映射配置-->
<servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <!--这里统一写/-->
    <url-pattern>/</url-pattern>
</servlet-mapping>

<multipart-config>
    <location>/tmp</location>
</multipart-config>

<form action="/upload" method="post" enctype="multipart/form-data">
    文件 <input type="file" name="file"/>
    <input type="submit" value="提交">
</form>

@RequestMapping("/upload")
public String upload(@RequestParam("file")MultipartFile file, HttpServletRequest request) {
    // 假如没有文件
    if (!file.isEmpty()) {
        // 获得文件原始名字
        String fileName = file.getOriginalFilename();
        // 获得文件的后缀名
        String fileSuffix = fileName.substring(fileName.lastIndexOf("."));
        // 取新的名字 UUID可以保证产生的名字不一样，产生全球唯一的ID
        String newName = UUID.randomUUID() + fileSuffix;
        // 获取文件存储目录地址
        String filePath = request.getSession().getServletContext().getRealPath("/upload");

        File fileForPath = new File(filePath);
        // 如果文件不存在
        if (!fileForPath.exists()) {
            // 新建文件
            fileForPath.mkdir();
        }

        File targetFile = new File(filePath, newName);
        try {
            // 将文件写入
            file.transferTo(targetFile);
        } catch (IOException e) {
            e.printStackTrace();
        }
    } else {
        System.out.println("文件不存在");
    }
    return "test";
}

@RequestMapping("down")
public String down(HttpServletResponse response,HttpServletRequest request){

    // 假如我的文件在/home/xiaohiu/images/鬼刀.jpg
    String fileName= "鬼刀.jpg";

    String parentPath = "/home/xiaohiu/images";

    // 这时候path.toString就是/home/xiaohiu/images/鬼刀.jpg了
    Path path = Paths.get(parentPath,fileName);

    // 假如文件存在
    if (Files.exists(path)){
        // 取出后缀名 jpg
        String fileSuffix = fileName.substring(fileName.lastIndexOf(".")+1);
        // 设置ContentType，只有设置它，才会去下载
        response.setContentType("application/"+fileSuffix);

        try {
            // 添加头信息 同时对文件名重新编码防止中文名乱码
            response.addHeader("Content-Disposition","attachment;filename="+new String(fileName.getBytes("utf-8"),"ISO8859-1"));
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }

        try {
        // 使用输出流写出去
            Files.copy(path,response.getOutputStream());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }else {
        System.out.println("文件不存在");
    }
    return "test";
}