title: SpringMvc笔记
date: 2023-05-14 09:50:02
categories:
- 后端
- Java
tags: - Java
- Spring
三层架构:
- web层主要由servlet来处理,负责页面请求和数据的收集以及响应结果给前端
- service层主要负责业务逻辑的处理
- dao层主要负责数据的增删改查操作
MVC设计模式:将其设计为controller
、view
和Model
- controller负责请求和数据的接收,接收后将其转发给service进行业务处理
- service根据需要会调用dao对数据进行增删改查
- dao把数据处理完后将结果交给service,service再交给controller
- controller根据需求组装成Model和View,Model和View组合起来生成页面转发给前端浏览器
- 这样做的好处就是controller可以处理多个请求,并对请求进行分发,执行不同的业务操作。
项目创建
- 导入jar包
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.2.10.RELEASE</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.tomcat.maven</groupId>
<artifactId>tomcat7-maven-plugin</artifactId>
<version>2.1</version>
<configuration>
<port>80</port>
<path>/</path>
</configuration>
</plugin>
</plugins>
</build>
- 创建配置类
@Configuration
@ComponentScan("com.itheima.controller")
public class SpringMvcConfig {
}
- 创建Controller类
@Controller
public class UserController {
@RequestMapping("/save")
@ResponseBody //不加默认是去找页面,找不到会报404,设置当前控制器方法响应内容为当前返回值,无需解析
public String save(){
System.out.println("user save ...");
return "{'info':'springmvc'}";
}
}
- 使用配置类代替web.xml
public class ServletContainersInitConfig extends AbstractDispatcherServletInitializer {
//加载springmvc配置类
protected WebApplicationContext createServletApplicationContext() {
//初始化WebApplicationContext对象
AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
//加载指定配置类
ctx.register(SpringMvcConfig.class);
return ctx;
}
//设置由springmvc控制器处理的请求映射路径
protected String[] getServletMappings() {
return new String[]{"/"};//代表所拦截请求的路径规则,只有被拦截后才能交给SpringMVC来处理请求
}
//加载spring配置类
protected WebApplicationContext createRootApplicationContext() {
return null;
}
}
问题:controller、service和dao这些类都需要被容器管理成bean对象,那么到底是该让SpringMVC加载还是让Spring加载呢?
- SpringMVC加载其相关bean(表现层bean),也就是controller包下的类
- Spring控制的bean
- 业务bean(Service)
- 功能bean(DataSource,SqlSessionFactoryBean,MapperScannerConfigurer等)
在SpringMvcConfig中扫描到的包为:@ComponentScan(“com.itheima.controller”)
在SpringConfig中扫描到的包为:@ComponentScan(“com.itheima”)
我们发现Spring会多把SpringMVC的controller类也扫描到,有如下解决方式:
- 方式一:Spring加载的bean设定扫描范围为精准范围,例如service包、dao包等
@Configuration @ComponentScan({"com.itheima.service","comitheima.dao"}) public class SpringConfig { }
- 方式二:Spring加载的bean设定扫描范围为com.itheima,排除掉controller包中的bean
@Configuration @ComponentScan(value="com.itheima", excludeFilters=@ComponentScan.Filter( type = FilterType.ANNOTATION, classes = Controller.class ) ) public class SpringConfig { }
- 方式三:不区分Spring与SpringMVC的环境,加载到同一个环境中[了解即可]
有了Spring的配置类,要想在tomcat服务器启动将其加载,我们需要修改ServletContainersInitConfig
public class ServletContainersInitConfig extends AbstractDispatcherServletInitializer {
protected WebApplicationContext createServletApplicationContext() {
AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
ctx.register(SpringMvcConfig.class);
return ctx;
}
protected String[] getServletMappings() {
return new String[]{"/"};
}
protected WebApplicationContext createRootApplicationContext() {
AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
ctx.register(SpringConfig.class);
return ctx;
}
}
上面这个代码有更简单的方式替代:
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[]{"/"};
}
}
请求与响应:
设置请求映射路径
对于Book模块的save,将其访问路径设置http://localhost/book/save
对于User模块的save,将其访问路径设置http://localhost/user/save
@Controller
public class UserController {
@RequestMapping("/user/save")
@ResponseBody
public String save(){
System.out.println("user save ...");
return "{'module':'user save'}";
}
}
@Controller
public class BookController {
@RequestMapping("/book/save")
@ResponseBody
public String save(){
System.out.println("book save ...");
return "{'module':'book save'}";
}
}
这样太麻烦了,可以简单一点:
@Controller
@RequestMapping("/user")
public class UserController {
@RequestMapping("/save")
@ResponseBody
public String save(){
System.out.println("user save ...");
return "{'module':'user save'}";
}
}
@Controller
@RequestMapping("/book")
public class BookController {
@RequestMapping("/save")
@ResponseBody
public String save(){
System.out.println("book save ...");
return "{'module':'book save'}";
}
}
请求参数
GET/POST请求发送单个参数: http://localhost/commonParam?name=itcast
@Controller
public class UserController {
@RequestMapping("/commonParam")
@ResponseBody
public String commonParam(String name){
System.out.println("普通参数传递 name ==> "+name);
return "{'module':'commonParam'}";
}
}
GET请求发送多个请求参数:http://localhost/commonParam?name=itcast&age=15
@Controller
public class UserController {
@RequestMapping("/commonParam")
@ResponseBody
public String commonParam(String name,int age){
System.out.println("普通参数传递 name ==> "+name);
System.out.println("普通参数传递 age ==> "+age);
return "{'module':'commonParam'}";
}
}
如果GET请求参数中有中文,乱码解决:Tomcat8.5以后的版本已经处理了中文乱码的问题
<build> <plugins> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <version>2.1</version> <configuration> <port>80</port><!--tomcat端口号--> <path>/</path> <!--虚拟目录--> <uriEncoding>UTF-8</uriEncoding><!--访问路径编解码字符集--> </configuration> </plugin> </plugins> </build>
如果POST请求出现中文乱码:需要配置过滤器:
public class ServletContainersInitConfig extends AbstractAnnotationConfigDispatcherServletInitializer { protected Class<?>[] getRootConfigClasses() { return new Class[0]; } 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}; } }
五种类型参数传递
普通参数
url地址传参,地址参数名与形参变量名相同,定义形参即可接收参数。
请求:http://localhost/commonParamDifferentName?name=张三&age=18
后台:
@RequestMapping("/commonParamDifferentName")
@ResponseBody
public String commonParamDifferentName(String userName , int age){
System.out.println("普通参数传递 userName ==> "+userName);
System.out.println("普通参数传递 age ==> "+age);
return "{'module':'common param different name'}";
}
此时的userName与前端不对应,需要使用@RequestParam注解
@RequestMapping("/commonParamDifferentName")
@ResponseBody
public String commonParamDifferentName(@RequestPaam("name") String userName , int age){
System.out.println("普通参数传递 userName ==> "+userName);
System.out.println("普通参数传递 age ==> "+age);
return "{'module':'common param different name'}";
}
POJO参数
User类
public class User {
private String name;
private int age;
}
前端请求:
后端:
//POJO参数:请求参数与形参对象中的属性对应即可完成参数传递
@RequestMapping("/pojoParam")
@ResponseBody
public String pojoParam(User user){
System.out.println("pojo参数传递 user ==> "+user);
return "{'module':'pojo param'}";
}
请求参数key的名称要和POJO中属性的名称一致,否则无法封装。
嵌套POJO类型参数
Adress类和User类
public class Address {
private String province;
private String city;
}
public class User {
private String name;
private int age;
private Address address;
}
前端请求:
后端:
//POJO参数:请求参数与形参对象中的属性对应即可完成参数传递
@RequestMapping("/pojoParam")
@ResponseBody
public String pojoParam(User user){
System.out.println("pojo参数传递 user ==> "+user);
return "{'module':'pojo param'}";
}
数组类型参数
前端:
后端:
//数组参数:同名请求参数可以直接映射到对应名称的形参数组对象中
@RequestMapping("/arrayParam")
@ResponseBody
public String arrayParam(String[] likes){
System.out.println("数组参数传递 likes ==> "+ Arrays.toString(likes));
return "{'module':'array param'}";
}
集合类型参数
前端:
后端:
//集合参数:同名请求参数可以使用@RequestParam注解映射到对应名称的集合对象中作为数据
@RequestMapping("/listParam")
@ResponseBody
public String listParam(List<String> likes){
System.out.println("集合参数传递 likes ==> "+ likes);
return "{'module':'list param'}";
}
这样做会报错,因为SpringMVC会将List看做是POJO对象,但是List接口无法创建对象,可以使用@RequestParam注解
//集合参数:同名请求参数可以使用@RequestParam注解映射到对应名称的集合对象中作为数据
@RequestMapping("/listParam")
@ResponseBody
public String listParam(@RequestParam List<String> likes){
System.out.println("集合参数传递 likes ==> "+ likes);
return "{'module':'list param'}";
}
JSON格式数据传输
JSON普通数组
- SpringMVC默认使用的是jackson来处理json的转换,所以需要在pom.xml添加jackson依赖
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.0</version>
</dependency>
- 开启SpringMVC注解支持
@Configuration
@ComponentScan("com.itheima.controller")
//开启json数据类型自动转换
@EnableWebMvc
public class SpringMvcConfig {
}
- 参数前添加@RequestBody
//使用@RequestBody注解将外部传递的json数组数据映射到形参的集合对象中作为数据
@RequestMapping("/listParamForJson")
@ResponseBody
public String listParamForJson(@RequestBody List<String> likes){
System.out.println("list common(json)参数传递 list ==> "+likes);
return "{'module':'list common for json param'}";
}
JSON对象数据
前端:
后端:
@RequestMapping("/pojoParamForJson")
@ResponseBody
public String pojoParamForJson(@RequestBody User user){
System.out.println("pojo(json)参数传递 user ==> "+user);
return "{'module':'pojo for json param'}";
}
JSON对象数组
前端:
后端:
@RequestMapping("/listPojoParamForJson")
@ResponseBody
public String listPojoParamForJson(@RequestBody List<User> list){
System.out.println("list pojo(json)参数传递 list ==> "+list);
return "{'module':'list pojo for json param'}";
}
日期参数传递
@RequestMapping("/dataParam")
@ResponseBody
public String dataParam(Date date)
System.out.println("参数传递 date ==> "+date);
return "{'module':'data param'}";
}
默认这种格式可以:http://localhost/dataParam?date=2088/08/08
其他格式:
前端:http://localhost/dataParam?date=2088/08/08&date1=2088-08-08
后端:
@RequestMapping("/dataParam")
@ResponseBody
public String dataParam(Date date,Date date1)
System.out.println("参数传递 date ==> "+date);
return "{'module':'data param'}";
}
此时会报错,需要进行日期格式的转换:
@RequestMapping("/dataParam")
@ResponseBody
public String dataParam(Date date, @DateTimeFormat(pattern="yyyy-MM-dd") Date date1)
System.out.println("参数传递 date ==> "+date);
System.out.println("参数传递 date1(yyyy-MM-dd) ==> "+date1);
return "{'module':'data param'}";
}
携带时间的日期:
前端:http://localhost/dataParam?date=2088/08/08&date1=2088-08-08&date2=2088/08/08 8:08:08
后端:
@RequestMapping("/dataParam")
@ResponseBody
public String dataParam(Date date,
@DateTimeFormat(pattern="yyyy-MM-dd") Date date1,
@DateTimeFormat(pattern="yyyy/MM/dd HH:mm:ss") Date date2)
System.out.println("参数传递 date ==> "+date);
System.out.println("参数传递 date1(yyyy-MM-dd) ==> "+date1);
System.out.println("参数传递 date2(yyyy/MM/dd HH:mm:ss) ==> "+date2);
return "{'module':'data param'}";
}
响应
响应页面
不加@ResponseBody,默认是返回jsp页面
@Controller
public class UserController {
@RequestMapping("/toJumpPage")
//注意
//1.此处不能添加@ResponseBody,如果加了该注入,会直接将page.jsp当字符串返回前端
//2.方法需要返回String
public String toJumpPage(){
System.out.println("跳转页面");
return "page.jsp";
}
}
返回文本数据:
@Controller
public class UserController {
@RequestMapping("/toText")
//注意此处该注解就不能省略,如果省略了,会把response text当前页面名称去查找,如果没有回报404错误
@ResponseBody
public String toText(){
System.out.println("返回纯文本数据");
return "response text";
}
}
响应JSON数据:
@Controller
public class UserController {
@RequestMapping("/toJsonPOJO")
@ResponseBody
public User toJsonPOJO(){
System.out.println("返回json对象数据");
User user = new User();
user.setName("itcast");
user.setAge(15);
return user;
}
}
需要依赖@ResponseBody注解和@EnableWebMvc注解
响应POJO集合对象
@Controller
public class UserController {
@RequestMapping("/toJsonList")
@ResponseBody
public List<User> toJsonList(){
System.out.println("返回json集合数据");
User user1 = new User();
user1.setName("传智播客");
user1.setAge(15);
User user2 = new User();
user2.setName("黑马程序员");
user2.setAge(12);
List<User> userList = new ArrayList<User>();
userList.add(user1);
userList.add(user2);
return userList;
}
}
此处使用到了类型转换,内部还是通过Converter接口的实现类完成的,它还可以实现:
- 对象转Json数据(POJO -> json)
- 集合转Json数据(Collection -> json)
REST风格
按照不同的请求方式代表不同的操作类型。
- 发送GET请求是用来做查询
- 发送POST请求是用来做新增
- 发送PUT请求是用来做修改
- 发送DELETE请求是用来做删除
UserController
@Controller
public class UserController {
@RequestMapping("/save")
@ResponseBody
public String save(@RequestBody User user) {
System.out.println("user save..."+user);
return "{'module':'user save'}";
}
@RequestMapping("/delete")
@ResponseBody
public String delete(Integer id) {
System.out.println("user delete..." + id);
return "{'module':'user delete'}";
}
@RequestMapping("/update")
@ResponseBody
public String update(@RequestBody User user) {
System.out.println("user update..." + user);
return "{'module':'user update'}";
}
@RequestMapping("/getById")
@ResponseBody
public String getById(Integer id) {
System.out.println("user getById..." + id);
return "{'module':'user getById'}";
}
@RequestMapping("/findAll")
@ResponseBody
public String getAll() {
System.out.println("user getAll...");
return "{'module':'user getAll'}";
}
}
将上面代码更换RESTful风格如下:
新增:请求路径更改为/users
,请求方式为POST
//设置当前请求方法为POST,表示REST风格中的添加操作
@RequestMapping(value = "/users",method = RequestMethod.POST)
@ResponseBody
public String save() {
System.out.println("user save...");
return "{'module':'user save'}";
}
删除:这里在删除时需要携带路径参数,例如http://localhost/users/1
- 修改@RequestMapping的value属性,将其中修改为
/users/{id}
,目的是和路径匹配 - 在方法的形参前添加@PathVariable注解
@Controller
public class UserController {
//设置当前请求方法为DELETE,表示REST风格中的删除操作
@RequestMapping(value = "/users/{id}",method = RequestMethod.DELETE)
@ResponseBody
public String delete(@PathVariable Integer id) {
System.out.println("user delete..." + id);
return "{'module':'user delete'}";
}
}
多个参数:例如:http://localhost/users/1/tom
@Controller
public class UserController {
//设置当前请求方法为DELETE,表示REST风格中的删除操作
@RequestMapping(value = "/users/{id}/{name}",method = RequestMethod.DELETE)
@ResponseBody
public String delete(@PathVariable Integer id,@PathVariable String name) {
System.out.println("user delete..." + id+","+name);
return "{'module':'user delete'}";
}
}
还可以更简单,如下进行增删改查操作:
@RestController //@Controller + ReponseBody
@RequestMapping("/books")
public class BookController {
@PostMapping
public String save(@RequestBody Book book){
System.out.println("book save..." + book);
return "{'module':'book save'}";
}
@DeleteMapping("/{id}")
public String delete(@PathVariable Integer id){
System.out.println("book delete..." + id);
return "{'module':'book delete'}";
}
@PutMapping
public String update(@RequestBody Book book){
System.out.println("book update..." + book);
return "{'module':'book update'}";
}
@GetMapping("/{id}")
public String getById(@PathVariable Integer id){
System.out.println("book getById..." + id);
return "{'module':'book getById'}";
}
@GetMapping
public String getAll(){
System.out.println("book getAll...");
return "{'module':'book getAll'}";
}
}
SpringMVC放行静态资源:
@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
//设置静态资源访问过滤,当前类需要设置为配置类,并被扫描加载
@Override
protected void addResourceHandlers(ResourceHandlerRegistry registry) {
//当访问/pages/????时候,从/pages目录下查找内容
registry.addResourceHandler("/pages/**").addResourceLocations("/pages/");
registry.addResourceHandler("/js/**").addResourceLocations("/js/");
registry.addResourceHandler("/css/**").addResourceLocations("/css/");
registry.addResourceHandler("/plugins/**").addResourceLocations("/plugins/");
}
}
然后进行扫描到这个类:
@Configuration
@ComponentScan({"com.itheima.controller","com.itheima.config"})
@EnableWebMvc
public class SpringMvcConfig {
}
或者
@Configuration
@ComponentScan("com.itheima")
@EnableWebMvc
public class SpringMvcConfig {
}