SpringMVC 框架的使用2

java小小小小栈 2021-01-25

153

@RestController。Controller 类上加了@RestController 注解，等价于在类中的每个方法上都加了@ResponseBody，全局返回 json 数据。



// JsonRestController.java


@RestController
@RequestMapping("/jsonrest")
public class JsonRestController {


    @RequestMapping("/demo1")
    public User demo1() {
        User user = new User();
        user.setUsername("张三");
        user.setAge(12);
        return user;
    }


}

@RequestBody。将请求体中的 json 数据转换为 java 对象。



// JsonRestController.java


@RestController
@RequestMapping("/jsonrest")
public class JsonRestController {


    @RequestMapping("/demo2")
    public String demo2(@RequestBody User user) {
        System.out.println(user);
        return "kk";
    }
}

FastJson 使用。



// pom.xml


<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.54</version>
</dependency>



// mvc.xml


<mvc:annotation-driven>
    <!-- 安装FastJson,转换器 -->
    <mvc:message-converters>
        <bean class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
            <!-- 声明转换类型:json -->
            <property name="supportedMediaTypes">
                <list>
                    <value>application/json</value>
                </list>
            </property>
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>

异常解析器，统一处理 Controller 的异常。



// springmvc 全局异常解析


// 1 注解自动关联；2 bean 关联
//@Component
public class MyExecptionHandle implements HandlerExceptionResolver {




    @Override
    public ModelAndView resolveException(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) {


        ModelAndView mv = new ModelAndView();


        if (e instanceof  ArithmeticException) {
            mv.setViewName("error1");
        } else if (e instanceof  RuntimeException) {
            mv.setViewName("error2");
        } else if (e instanceof IOException) {
            mv.setViewName("error3");
        } else {
            mv.setViewName("error4");
        }


        return mv;
    }
}



// mvc.xml


<!--   注册异常 bean -->
    <bean class="com.baidu.day.text.exec.MyExecptionHandle"></bean>



// ExecController.java


@Controller
@RequestMapping("/exec")
public class ExecController {


    @RequestMapping("/demo1")
    public String demo1() {
        int i = 10 / 0;
        return "index";
    }


    @RequestMapping("/demo2")
    public String demo2() {
        if (true) {
            throw new RuntimeException("出错啦");
        }
        return "index";
    }


    @RequestMapping("/demo3")
    public String demo3() throws FileNotFoundException {


        new FileInputStream("xxx");


        return "index";
    }

拦截器。



// MyInterceptor.java


public class MyInterceptor implements HandlerInterceptor {




    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("拦截");


        HttpSession session = request.getSession();


        System.out.println("username" + session.getAttribute("username"));
        if (session.getAttribute("username") != null) {
            // 放行
            return true;
        }


        // 拦截之前给出响应
        response.sendRedirect(request.getContextPath() + "/login.jsp");
        // 拦截
        return false;
    }


    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
        System.out.println("返回数据再次处理");
    }


    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
        System.out.println("资源回收");
    }


}



// mvc.xml


<!--  拦截器  -->
    <mvc:interceptors>
        <mvc:interceptor>
            <!--  /*,匹配一级；/**，匹配多级路径    -->
            <mvc:mapping path="/inter/**"/>
            <mvc:exclude-mapping path="/inter/login"/>
            <!--  处理拦截         -->
            <bean class="com.baidu.day.text.interceptor.MyInterceptor"></bean>
        </mvc:interceptor>
    </mvc:interceptors>



// InterceptorController.java


@Controller
@RequestMapping("/inter")


public class InterceptorController {


    @RequestMapping("login")
    public String login(String username, String password) {
        System.out.println(username + "\n" + password);
        return "index";
    }


    @RequestMapping("/show")
    public String show(HttpSession session) {
        System.out.println("show");
        return "index";
    }


    @RequestMapping("/del/all")
    public String del() {
        System.out.println("del");
        return "index";
    }


}

上传和下载。



// pom.xml


  <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.4</version>
        </dependency>


        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.3.3</version>
            <exclusions>
                <exclusion>
                    <groupId>javax.servlet</groupId>
                    <artifactId>servlet-api</artifactId>
                </exclusion>
            </exclusions>
        </dependency>



// upload.jsp


<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <form method="post" action="/file/upload" enctype="multipart/form-data">


        <input type="file" name="files"><br>
        <input type="submit" value="上传">
    </form>


    <a href="/file/download?name=从前有座山.txt">下载</a>
</body>
</html>



// mvc.xml


<!--   文件上传解析器 -->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="maxUploadSize" value="1024000" />
    </bean>



// FileController.java


@Controller
@RequestMapping("/file")
public class FileController {


    @RequestMapping("/upload")
    @ResponseBody
    public String fileUpload(MultipartFile files, HttpServletRequest request, User user) throws IOException {


        String filename = files.getOriginalFilename();
        String name = files.getName();
        long size = files.getSize();
        String contentType = files.getContentType();
        String description = files.getResource().getDescription();
        System.out.println(filename + "\n" + name + "\n" + size + "\n" + contentType + "\n" + description + "\n");


        // 图片保存路径
        // mac 路径有问题，此路径是 tomcat 临时路径，tomcat 重启后文件会清空。仅做测试用。
        String realpath = request.getSession().getServletContext().getRealPath("/upload");
        System.out.println(realpath);


        File file = new File(realpath);
        if (!file.exists()) {
            file.mkdir();
        }
        files.transferTo(new File(realpath + "/" + filename));
        return "success";
    }


    @RequestMapping("/download")
    public void download(String name, HttpServletRequest request,HttpSession session, HttpServletResponse response) throws IOException {


        String realpath = session.getServletContext().getRealPath("/upload");
        String filepath = realpath + File.separator + name;


        System.out.println(filepath);


        // 中文编码后浏览器自动解码
        String encode = URLEncoder.encode(name,"utf-8");
        response.setHeader("Content-Disposition","attachment; filename=" + encode);
        IOUtils.copy(new FileInputStream(filepath), response.getOutputStream());


    }
}

验证码。



<dependency>
    <groupId>com.github.penggle</groupId>
    <artifactId>kaptcha</artifactId>
    <version>2.3.2</version>
    <exclusions>
        <exclusion>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
        </exclusion>
    </exclusions>
</dependency>

REST。是一种开发风格。不同的请求方式，对应相同的请求路径。



// 全局返回 json
@RestController
@RequestMapping("/rest")
public class MyRestController {


// 等同于   @RequestMapping(value = "/user",method = RequestMethod.GET)
    @GetMapping("/user")
    public String getAll() {
        System.out.println("getall");
        return "ok";
    }


    @PostMapping("/user")
    public String addUser() {
        System.out.println("addUser");
        return "ok";
    }


}

跨域请求。

新建一个工程，改变不同的 tomcat 名字，http port = 8081 和 jmx.port。



// http://localhost:8080/cross.jsp


<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <script src="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script>
    <script>
        $(function () {
            console.log("xx")
            $("#click").click(function () {
                console.log("dd")
                $.ajax({
                    url: "http://localhost:8081/json/demo1",
                    type: "get",
                    xhrFields: {
                        // 跨域携带cookie
                        withCredentials: true
                    },
                    success: function (data) {
                        console.log(data)
                    },
                    error: function (error) {
                        console.log(error)
                    }
                })
            })
        })
</script>
</head>
<body>


    <input id="click" type="button" value="点击1">


</body>
</html>



// MyRestController.java
// http://localhost:8081/rest/user


// 全局返回 json
@RestController
@RequestMapping("/rest")
// 允许其他域访问
@CrossOrigin("http://localhost:8080") 
public class MyRestController {


// 等同于   @RequestMapping(value = "/user",method = RequestMethod.GET)
    @GetMapping("/user")
    public String getAll() {
        System.out.println("getall");
        return "ok";
    }


    @PostMapping("/user")
    public String addUser() {
        System.out.println("addUser");
        return "ok";
    }


}

数据库

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SpringMVC 框架的使用2

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