SpringMVC入门案例

基于java实现MVC模型的轻量web框架，替换servlet技术完成表现层开发。

导入坐标

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<dependencies>
  <dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>4.0.1</version>
    <scope>provided</scope>
  </dependency>
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.2.10.RELEASE</version>
  </dependency>
</dependencies>
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<build>
    <plugins>
        <plugin>
            <groupId>org.apache.tomcat.maven</groupId>
            <artifactId>tomcat7-maven-plugin</artifactId>
            <version>2.2</version>
            <configuration>
                <port>
                    80
                </port>
            </configuration>
        </plugin>
    </plugins>
</build>

定义Controller bean

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@Controller
public class UserController {
    /*设置请求路径*/
    @RequestMapping("/save")
    /*定义返回体*/
    @ResponseBody
    public String save(){
        System.out.println("user save...");
        return "{'module':'springmvc'}";
    }
}

创建SpringMvcConfig类

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@Configuration
@ComponentScan("cola")
public class SpringMvcConfig {
}

定义Servlet容器启动配置类

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@Configuration
public class ServletContainersInitConfig extends AbstractDispatcherServletInitializer {
    /*加载SpringMVC容器配置*/
    protected WebApplicationContext createServletApplicationContext() {
        AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
        ctx.register(SpringMvcConfig.class);
        return ctx;
    }

    /*设置哪些请求归SpringMVC处理*/
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }

    /*加载Spring容器配置*/
    protected WebApplicationContext createRootApplicationContext() {
        AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
        ctx.register(SpringConfig.class);
        return ctx;
    }
}

在SpringConfig中排除Controller类

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@Configuration
@ComponentScan(value = "cola", excludeFilters = @ComponentScan.Filter(type = FilterType.ANNOTATION, classes = Controller.class))
public class SpringConfig {
}

Servlet容器启动配置类简化

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@Configuration
public class ServletContainersInitConfig extends AbstractAnnotationConfigDispatcherServletInitializer {

    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{SpringConfig.class};
    }

    protected Class<?>[] getServletConfigClasses() {
        return new Class[]{SpringMvcConfig.class};
    }

    protected String[] getServletMappings() {
        return new String[]{"/"};
    }
}

请求响应

普通参数

get和post不区分，直接添加形参都可以接受。

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@Controller
public class UserController {
    /*设置请求路径*/
    @RequestMapping("/save")
    /*定义返回体*/
    @ResponseBody
    public String save(String name, int age) {
        System.out.println("user save..." + name + age);
        return "{'module':'springmvc'}";
    }
}

中文乱码

在ServletContainersInitConfig中加入Filter。

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@Configuration
public class ServletContainersInitConfig extends AbstractAnnotationConfigDispatcherServletInitializer {

    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{SpringConfig.class};
    }

    protected Class<?>[] getServletConfigClasses() {
        return new Class[]{SpringMvcConfig.class};
    }

    protected String[] getServletMappings() {
        return new String[]{"/"};
    }

    /*乱码处理*/
    @Override
    protected Filter[] getServletFilters() {
        CharacterEncodingFilter filter = new CharacterEncodingFilter();
        filter.setEncoding("utf-8");
        return new Filter[]{filter};
    }
}

pojo参数

直接接受对象形参，框架会自动将请求中的参数填入对象中。

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@Controller
public class UserController {
    /*设置请求路径*/
    @RequestMapping("/save")
    /*定义返回体*/
    @ResponseBody
    public String save(User user) {
        System.out.println("user save..." + user);
        return "{'module':'springmvc'}";
    }
}

如果对象里嵌套有对象参数，例如user对象中有address对象参数，address对象中有name参数，在发送请求时，加入address.name参数即可。

数组参数

改变形参，发送请求时使用相同key名。

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@Controller
public class UserController {
    /*设置请求路径*/
    @RequestMapping("/save")
    /*定义返回体*/
    @ResponseBody
    public String save(String[] likes) {
        System.out.println("user save..." + Arrays.toString(likes));
        return "{'module':'springmvc'}";
    }
}

集合参数

同上，但需要添加注解@RequestParam，因为框架默认认为形参是需要一个pojo对象，而例如List不能创建对象。

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@Controller
public class UserController {
    /*设置请求路径*/
    @RequestMapping("/save")
    /*定义返回体*/
    @ResponseBody
    public String save(@RequestParam List<String> likes) {
        System.out.println("user save..." + likes);
        return "{'module':'springmvc'}";
    }
}

传递json数据

导包

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<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.9.0</version>
</dependency>

添加配置

在SpringMVC Config中加入注解@EnableWebMvc

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@Configuration
@ComponentScan("cola")
@EnableWebMvc
public class SpringMvcConfig {
}

在形参中加入注解@RequestBody

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@Controller
public class UserController {
    /*设置请求路径*/
    @RequestMapping("/save")
    /*定义返回体*/
    @ResponseBody
    public String save(@RequestBody List<String> likes) {
        System.out.println("user save..." + likes);
        return "{'module':'springmvc'}";
    }
}