1、SpringMVC
1、运行原理
Dispatcher— 前端控制器
HandlerMapping — 处理映射器
HandlerAdapter — 处理适配器
ViewResolver — 视图解析器
流程:
- 用户请求页面,
- 前端控制器调用处理映射器得到对应的请求信息
- 前端控制器调用处理适配器,执行对应的controller,得到数据后返回前端控制器,
- 前端控制器将得到的数据通过视图解析器解析
- 最后通过视图解析器跳转到对应的视图展示
2、第一个简单项目
- web.xml
<?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_4_0.xsd"
version="4.0">
<!--1.注册DispatcherServlet-->
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!--关联一个springmvc的配置文件:【servlet-name】-servlet.xml-->
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring.xml</param-value>
</init-param>
<!--启动级别-1-->
<load-on-startup>1</load-on-startup>
</servlet>
<!--/ 匹配所有的请求;(不包括.jsp)-->
<!--/* 匹配所有的请求;(包括.jsp)-->
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
- spring.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<!--添加 处理映射器-->
<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
<!--添加 处理器适配器-->
<bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>
<!--视图解析器:DispatcherServlet给他的ModelAndView-->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
<!--前缀-->
<property name="prefix" value="/WEB-INF/jsp/"/>
<!--后缀-->
<property name="suffix" value=".jsp"/>
</bean>
<!--Handler-->
<bean id="/hello" class="com.cl.controller.HelloController"/>
</beans>
- helloController
public class HelloController implements Controller {
public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
//ModelAndView 模型和视图
ModelAndView mv = new ModelAndView();
//封装对象,放在ModelAndView中。Model
mv.addObject("msg","HelloSpringMVC!");
//封装要跳转的视图,放在ModelAndView中
mv.setViewName("hello"); //: /WEB-INF/jsp/hello.jsp
return mv;
}
}
3、使用注解开发项目(常用)
- 配置web.xml
<?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_4_0.xsd"
version="4.0">
<!--1.注册DispatcherServlet-->
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!--关联一个springmvc的配置文件:【servlet-name】-servlet.xml-->
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring.xml</param-value>
</init-param>
<!--启动级别-1-->
<load-on-startup>1</load-on-startup>
</servlet>
<!--/ 匹配所有的请求;(不包括.jsp)-->
<!--/* 匹配所有的请求;(包括.jsp)-->
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<!--配置SpringMVC过滤器解决乱码问题-->
<filter>
<filter-name>encoding</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>utf-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encoding</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
- 配置spring.xml
<?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:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
https://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!--自动扫描包,让指定包下的注解生效,都ioc容器统一管理-->
<context:component-scan base-package="com.cl.controller"/>
<!--静态资源过滤 (jsp、js...) -->
<mvc:default-servlet-handler/>
<!--开启注解驱动 -->
<mvc:annotation-driven/>
<!--视图解析器:DispatcherServlet给他的ModelAndView-->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
<!--前缀-->
<property name="prefix" value="/WEB-INF/jsp/"/>
<!--后缀-->
<property name="suffix" value=".jsp"/>
</bean>
</beans>
- HelloController
@Controller
public class HelloController {
@RequestMapping("/hello")
public String send(Model model){
model.addAttribute("msg","hello word");
return "hello";
}
}
注意点:idea 要创建lib,并导包
4、重定向和转发
@Controller
public class HelloController {
@RequestMapping("/hello")
public String send(Model model){
model.addAttribute("msg","hello word");
//重定向
return "redirect:hello";
}
@RequestMapping("/hello2")
public String send2(Model model){
model.addAttribute("msg","hello word");
//转发
return "forward:hello";
}
}
- 视图解析器默认是转发, 不用视图解析器需要加 redirect、 forward 来实现重定向和转发。
5、 Json字符串
5.1、第一种使用Jackson
- 导入架包
<!-- jackson - json解析 -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.11.0</version>
</dependency>
- 将对象转换成Json字符串
@Controller
public class UserController {
@RequestMapping("/g1")
@ResponseBody
public String getUser() throws JsonProcessingException {
User user = new User();
user.setId(1);
user.setName("小王");
user.setAge(12);
ObjectMapper objectMapper = new ObjectMapper();
String s = objectMapper.writeValueAsString(user);
return s;
}
}
- SpringMVC解决Json字符串乱码(在Spring核心配置文件中配置)
<?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:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
https://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!--自动扫描包,让指定包下的注解生效,都ioc容器统一管理-->
<context:component-scan base-package="com.cl.controller"/>
<!--视图解析器:DispatcherServlet给他的ModelAndView-->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
<!--前缀-->
<property name="prefix" value="/WEB-INF/jsp/"/>
<!--后缀-->
<property name="suffix" value=".jsp"/>
</bean>
<!--springmvc 统一解决json中文乱码问题-->
<mvc:annotation-driven>
<mvc:message-converters register-defaults="true">
<bean class="org.springframework.http.converter.StringHttpMessageConverter">
<constructor-arg value="UTF-8"/>
</bean>
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<property name="objectMapper">
<bean class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
<property name="failOnEmptyBeans" value="false"/>
</bean>
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>
</beans>
5.2、第二种使用Fastjson(常用)
- 导入依赖架包
<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.72</version>
</dependency>
- 使用
1.json字符串转换为对象
String jsonString="{'idcard':'42313123','id':'2345'}";
Channelbankcard c =JSONObject.parseObject(jsonString, Channelbankcard.class);
System.out.println(c.getIdcard()+" "+c.getId()); //输出 42313123 2345
2.json字符串转换为map
@SuppressWarnings("unchecked")
Map<String,String> map = JSONObject.parseObject(jsonString, Map.class);
System.out.println(map.get("idcard")+" "+map.get("id")); //输出 42313123 2345
3.将对象转换为json字符串
String jsonstr=JSON.toJSONString(c);
System.out.println(jsonstr); //输出{"id":"2345","idcard":"42313123"}
4./将String转换成JSONObjct格式
String str = "{\"result\":\"success\",\"message\":\"成功!\"}";
JSONObject json;
json = JSONObject.parseObject(str);
System.out.println(json); //输出 {"result":"success","message":"成功!"}
5.将string转换成JSONArray
String str1 = "{\"result\":\"success\",\"message\":\"成功!\",\"data\":[{\"name\":\"Tom\",\"age\":\"20\"}]}";
JSONObject json;
json = JSONObject.parseObject(str1);
System.out.println(json);
//输出 {"result":"success","data":[{"name":"Tom","age":"20"}],"message":"成功!"}
JSONArray jsonArray = JSONArray.parseArray(json.getString("data"));
//输出 [{"name":"Tom","age":"20"}]
6、文件上传下载
@Controller
public class FIleUploadController {
//@RequestParam("file") 将name=file控件得到的文件封装成CommonsMultipartFile 对象
//批量上传CommonsMultipartFile则为数组即可
@RequestMapping("/upload")
public String fileUpload(@RequestParam("file") CommonsMultipartFile file , HttpServletRequest request) throws IOException {
//获取文件名 : file.getOriginalFilename();
String uploadFileName = file.getOriginalFilename();
//如果文件名为空,直接回到首页!
if ("".equals(uploadFileName)){
return "redirect:/index.jsp";
}
System.out.println("上传文件名 : "+uploadFileName);
//上传路径保存设置
String path = request.getServletContext().getRealPath("/upload");
//如果路径不存在,创建一个
File realPath = new File(path);
if (!realPath.exists()){
realPath.mkdir();
}
System.out.println("上传文件保存地址:"+realPath);
InputStream is = file.getInputStream(); //文件输入流
OutputStream os = new FileOutputStream(new File(realPath,uploadFileName)); //文件输出流
//读取写出
int len=0;
byte[] buffer = new byte[1024];
while ((len=is.read(buffer))!=-1){
os.write(buffer,0,len);
os.flush();
}
os.close();
is.close();
return "redirect:/index.jsp";
}
@RequestMapping(value="/download")
public String downloads(HttpServletResponse response , HttpServletRequest request) throws Exception{
//要下载的图片地址
String path = request.getServletContext().getRealPath("/upload");
String fileName = "基础语法.jpg";
//1、设置response 响应头
response.reset(); //设置页面不缓存,清空buffer
response.setCharacterEncoding("UTF-8"); //字符编码
response.setContentType("multipart/form-data"); //二进制传输数据
//设置响应头
response.setHeader("Content-Disposition",
"attachment;fileName="+ URLEncoder.encode(fileName, "UTF-8"));
File file = new File(path,fileName);
//2、 读取文件--输入流
InputStream input=new FileInputStream(file);
//3、 写出文件--输出流
OutputStream out = response.getOutputStream();
byte[] buff =new byte[1024];
int index=0;
//4、执行 写出操作
while((index= input.read(buff))!= -1){
out.write(buff, 0, index);
out.flush();
}
out.close();
input.close();
return null;
}
}
https://www.bilibili.com/video/BV1aE41167Tu?p=29