顺利完成模块二的学习,正式进入模块三。
<filter>
<filter-name>hiddenHttpMethodFilterfilter-name>
<filter-class>org.springframework.web.filter.HiddenHttpMethodFilterfilter-
class>
filter>
<filter-mapping>
<filter-name>encodingfilter-name>
<url-pattern>/*url-pattern>
filter-mapping>
<filter-mapping>
<filter-name>hiddenHttpMethodFilterfilter-name>
<url-pattern>/*url-pattern>
filter-mapping>
交互:两个⽅向
1)前端到后台:前端ajax发送json格式字符串,后台直接接收为pojo参数,使⽤注解@RequstBody
2)后台到前端:后台直接返回pojo对象,前端直接接收为json对象或者字符串,使⽤注解@ResponseBody
Json是⼀种与语⾔⽆关的数据交互格式,就是⼀种字符串,只是⽤特殊符号{}内表示对象、[]内表示数组、""内是属性或值、:表示后者是前者的值
{“name”: “Michael”}可以理解为是⼀个包含name为Michael的对象
[{“name”: “Michael”},{“name”: “Jerry”}]就表示包含两个对象的数组
@ResponseBody注解的作⽤是将controller的⽅法返回的对象通过适当的转换器转换为指定的格式之后,写⼊到response对象的body区,通常⽤来返回JSON数据或者是XML数据。 注意:在使⽤此注解之后不会再⾛视图处理器,⽽是直接将数据写⼊到输⼊流中,他的效果等同于通过response对象输出指定格式的数据。
<div>
<h2>Ajax json交互h2>
<fieldset>
<input type="button" id="ajaxBtn" value="ajax提交"/>
fieldset>
div>
$(function () {
$("#ajaxBtn").bind("click",function () {
// 发送ajax请求
$.ajax({
url: '/demo/handle07',
type: 'POST',
data: '{"id":"1","name":"李四"}',
contentType: 'application/json;charset=utf-8',
dataType: 'json',
success: function (data) {
alert(data.name);
}
})
})
})
//注册SpringMVC拦截器
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<mvc:exclude-mapping path="/demo/**"/>
<bean class="com.lagou.edu.interceptor.MyIntercepter01"/>
mvc:interceptor>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<bean class="com.lagou.edu.interceptor.MyIntercepter02"/>
mvc:interceptor>
mvc:interceptors>
<bean id="multipartResolver"
class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="maxUploadSize" value="1000000000"/>
bean>
<%--
1 method="post"
2 enctype="multipart/form-data"
3 type="file"
--%>
<form method="post" enctype="multipart/form-data" action="/demo/upload">
<input type="file" name="uploadFile"/>
<input type="submit" value="上传"/>
form>
@RequestMapping("upload")
public String upload(MultipartFile uploadFile, HttpServletRequest request)
throws IOException {
// ⽂件原名,如xxx.jpg
String originalFilename = uploadFile.getOriginalFilename();
// 获取⽂件的扩展名,如jpg
String extendName =
originalFilename.substring(originalFilename.lastIndexOf(".") + 1,
originalFilename.length());
String uuid = UUID.randomUUID().toString();
// 新的⽂件名字
String newName = uuid + "." + extendName;
String realPath =
request.getSession().getServletContext().getRealPath("/uploads");
// 解决⽂件夹存放⽂件数量限制,按⽇期存放
String datePath = new SimpleDateFormat("yyyy-MM-dd").format(new Date());
File floder = new File(realPath + "/" + datePath);
if(!floder.exists()) {
floder.mkdirs();
}
uploadFile.transferTo(new File(floder,newName));
return "success";
}
// 可以让我们优雅的捕获所有Controller对象handler⽅法抛出的异常
@ControllerAdvice
public class GlobalExceptionResolver {
@ExceptionHandler(ArithmeticException.class)
public ModelAndView handleException(ArithmeticException exception,
HttpServletResponse response) {
ModelAndView modelAndView = new ModelAndView();
modelAndView.addObject("msg",exception.getMessage());
modelAndView.setViewName("error");
return modelAndView;
}
}
/**
* SpringMVC 重定向时参数传递的问题
* 转发:A 找 B 借钱400,B没有钱但是悄悄的找到C借了400块钱给A
* url不会变,参数也不会丢失,⼀个请求
* 重定向:A 找 B 借钱400,B 说我没有钱,你找别⼈借去,那么A ⼜带着400块的借钱需求找到
C
* url会变,参数会丢失需要重新携带参数,两个请求
*/
@RequestMapping("/handleRedirect")
public String handleRedirect(String name,RedirectAttributes redirectAttributes) {
//return "redirect:handle01?name=" + name; // 拼接参数安全性、参数⻓度都有局限
// addFlashAttribute⽅法设置了⼀个flash类型属性,该属性会被暂存到session中,在跳转到⻚⾯之后该属性销毁
redirectAttributes.addFlashAttribute("name",name);
return "redirect:handle01";
}
//只展示最重要的自定义DispatcherServlet部分
public class LhDispatcherServlet extends HttpServlet {
private Properties properties = new Properties();
private List<String> classNames = new ArrayList<>(); // 缓存扫描到的类的全限定类名
// ioc容器
private Map<String,Object> ioc = new HashMap<String,Object>();
// handlerMapping
//private Map handlerMapping = now HashMap<>(); // 存储url和Method之间的映射关系
private List<Handler> handlerMapping = new ArrayList<>();
@Override
public void init(ServletConfig config) throws ServletException {
// 1 加载配置文件 springmvc.properties
String contextConfigLocation = config.getInitParameter("contextConfigLocation");
doLoadConfig(contextConfigLocation);
// 2 扫描相关的类,扫描注解
doScan(properties.getProperty("scanPackage"));
// 3 初始化bean对象(实现ioc容器,基于注解)
doInstance();
// 4 实现依赖注入
doAutoWired();
// 5 构造一个HandlerMapping处理器映射器,将配置好的url和Method建立映射关系
initHandlerMapping();
System.out.println("lagou mvc 初始化完成....");
// 等待请求进入,处理请求
}
/*
构造一个HandlerMapping处理器映射器
最关键的环节
目的:将url和method建立关联
*/
private void initHandlerMapping() {
if(ioc.isEmpty()) {return;}
for(Map.Entry<String,Object> entry: ioc.entrySet()) {
// 获取ioc中当前遍历的对象的class类型
Class<?> aClass = entry.getValue().getClass();
if(!aClass.isAnnotationPresent(LagouController.class)) {continue;}
String baseUrl = "";
if(aClass.isAnnotationPresent(LagouRequestMapping.class)) {
LagouRequestMapping annotation = aClass.getAnnotation(LagouRequestMapping.class);
baseUrl = annotation.value(); // 等同于/demo
}
// 获取方法
Method[] methods = aClass.getMethods();
for (int i = 0; i < methods.length; i++) {
Method method = methods[i];
// 方法没有标识LagouRequestMapping,就不处理
if(!method.isAnnotationPresent(LagouRequestMapping.class)) {continue;}
// 如果标识,就处理
LagouRequestMapping annotation = method.getAnnotation(LagouRequestMapping.class);
String methodUrl = annotation.value(); // /query
String url = baseUrl + methodUrl; // 计算出来的url /demo/query
// 把method所有信息及url封装为一个Handler
Handler handler = new Handler(entry.getValue(),method, Pattern.compile(url));
// 计算方法的参数位置信息 // query(HttpServletRequest request, HttpServletResponse response,String name)
Parameter[] parameters = method.getParameters();
for (int j = 0; j < parameters.length; j++) {
Parameter parameter = parameters[j];
if(parameter.getType() == HttpServletRequest.class || parameter.getType() == HttpServletResponse.class) {
// 如果是request和response对象,那么参数名称写HttpServletRequest和HttpServletResponse
handler.getParamIndexMapping().put(parameter.getType().getSimpleName(),j);
}else{
handler.getParamIndexMapping().put(parameter.getName(),j); //
}
}
// 建立url和method之间的映射关系(map缓存起来)
handlerMapping.add(handler);
}
}
}
// 实现依赖注入
private void doAutoWired() {
if(ioc.isEmpty()) {return;}
// 有对象,再进行依赖注入处理
// 遍历ioc中所有对象,查看对象中的字段,是否有@LagouAutowired注解,如果有需要维护依赖注入关系
for(Map.Entry<String,Object> entry: ioc.entrySet()) {
// 获取bean对象中的字段信息
Field[] declaredFields = entry.getValue().getClass().getDeclaredFields();
// 遍历判断处理
for (int i = 0; i < declaredFields.length; i++) {
Field declaredField = declaredFields[i]; // @LagouAutowired private IDemoService demoService;
if(!declaredField.isAnnotationPresent(LagouAutowired.class)) {
continue;
}
// 有该注解
LagouAutowired annotation = declaredField.getAnnotation(LagouAutowired.class);
String beanName = annotation.value(); // 需要注入的bean的id
if("".equals(beanName.trim())) {
// 没有配置具体的bean id,那就需要根据当前字段类型注入(接口注入) IDemoService
beanName = declaredField.getType().getName();
}
// 开启赋值
declaredField.setAccessible(true);
try {
declaredField.set(entry.getValue(),ioc.get(beanName));
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
}
}
// ioc容器
// 基于classNames缓存的类的全限定类名,以及反射技术,完成对象创建和管理
private void doInstance() {
if(classNames.size() == 0) return;
try{
for (int i = 0; i < classNames.size(); i++) {
String className = classNames.get(i); // com.lagou.demo.controller.DemoController
// 反射
Class<?> aClass = Class.forName(className);
// 区分controller,区分service'
if(aClass.isAnnotationPresent(LagouController.class)) {
// controller的id此处不做过多处理,不取value了,就拿类的首字母小写作为id,保存到ioc中
String simpleName = aClass.getSimpleName();// DemoController
String lowerFirstSimpleName = lowerFirst(simpleName); // demoController
Object o = aClass.newInstance();
ioc.put(lowerFirstSimpleName,o);
}else if(aClass.isAnnotationPresent(LagouService.class)) {
LagouService annotation = aClass.getAnnotation(LagouService.class);
//获取注解value值
String beanName = annotation.value();
// 如果指定了id,就以指定的为准
if(!"".equals(beanName.trim())) {
ioc.put(beanName,aClass.newInstance());
}else{
// 如果没有指定,就以类名首字母小写
beanName = lowerFirst(aClass.getSimpleName());
ioc.put(beanName,aClass.newInstance());
}
// service层往往是有接口的,面向接口开发,此时再以接口名为id,放入一份对象到ioc中,便于后期根据接口类型注入
Class<?>[] interfaces = aClass.getInterfaces();
for (int j = 0; j < interfaces.length; j++) {
Class<?> anInterface = interfaces[j];
// 以接口的全限定类名作为id放入
ioc.put(anInterface.getName(),aClass.newInstance());
}
}else{
continue;
}
}
}catch (Exception e) {
e.printStackTrace();
}
}
// 首字母小写方法
public String lowerFirst(String str) {
char[] chars = str.toCharArray();
if('A' <= chars[0] && chars[0] <= 'Z') {
chars[0] += 32;
}
return String.valueOf(chars);
}
// 扫描类
// scanPackage: com.lagou.demo package----> 磁盘上的文件夹(File) com/lagou/demo
private void doScan(String scanPackage) {
String scanPackagePath = Thread.currentThread().getContextClassLoader().getResource("").getPath() + scanPackage.replaceAll("\\.", "/");
File pack = new File(scanPackagePath);
File[] files = pack.listFiles();
for(File file: files) {
if(file.isDirectory()) { // 子package
// 递归
doScan(scanPackage + "." + file.getName()); // com.lagou.demo.controller
}else if(file.getName().endsWith(".class")) {
String className = scanPackage + "." + file.getName().replaceAll(".class", "");
classNames.add(className);
}
}
}
// 加载配置文件
private void doLoadConfig(String contextConfigLocation) {
InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream(contextConfigLocation);
try {
properties.load(resourceAsStream);
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 处理请求:根据url,找到对应的Method方法,进行调用
// 获取uri
// String requestURI = req.getRequestURI();
// Method method = handlerMapping.get(requestURI);// 获取到一个反射的方法
// 反射调用,需要传入对象,需要传入参数,此处无法完成调用,没有把对象缓存起来,也没有参数!!!!改造initHandlerMapping();
// method.invoke() //
// 根据uri获取到能够处理当前请求的hanlder(从handlermapping中(list))
Handler handler = getHandler(req);
if(handler == null) {
resp.getWriter().write("404 not found");
return;
}
// 参数绑定
// 获取所有参数类型数组,这个数组的长度就是我们最后要传入的args数组的长度
Class<?>[] parameterTypes = handler.getMethod().getParameterTypes();
// 根据上述数组长度创建一个新的数组(参数数组,是要传入反射调用的)
Object[] paraValues = new Object[parameterTypes.length];
// 以下就是为了向参数数组中塞值,而且还得保证参数的顺序和方法中形参顺序一致
Map<String, String[]> parameterMap = req.getParameterMap();
// 遍历request中所有参数 (填充除了request,response之外的参数)
for(Map.Entry<String,String[]> param: parameterMap.entrySet()) {
// name=1&name=2 name [1,2]
String value = StringUtils.join(param.getValue(), ","); // 如同 1,2
// 如果参数和方法中的参数匹配上了,填充数据
if(!handler.getParamIndexMapping().containsKey(param.getKey())) {continue;}
// 方法形参确实有该参数,找到它的索引位置,对应的把参数值放入paraValues
Integer index = handler.getParamIndexMapping().get(param.getKey());//name在第 2 个位置
paraValues[index] = value; // 把前台传递过来的参数值填充到对应的位置去
}
int requestIndex = handler.getParamIndexMapping().get(HttpServletRequest.class.getSimpleName()); // 0
paraValues[requestIndex] = req;
int responseIndex = handler.getParamIndexMapping().get(HttpServletResponse.class.getSimpleName()); // 1
paraValues[responseIndex] = resp;
// 最终调用handler的method属性
try {
handler.getMethod().invoke(handler.getController(),paraValues);
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
}
private Handler getHandler(HttpServletRequest req) {
if(handlerMapping.isEmpty()){return null;}
String url = req.getRequestURI();
for(Handler handler: handlerMapping) {
Matcher matcher = handler.getPattern().matcher(url);
if(!matcher.matches()){continue;}
return handler;
}
return null;
}
}
Spring Data Jpa 是应⽤于Dao层的⼀个框架,简化数据库开发的,作⽤和Mybatis框架⼀样,但是在使⽤⽅式和底层机制是有所不同的。最明显的⼀个特点,Spring Data Jpa 开发Dao的时候,很多场景我们连sql语句都不需要开发。由Spring出品。
Spring Data JPA 是 Spring 基于JPA 规范的基础上封装的⼀套 JPA 应⽤框架,可使开发者⽤极简的代码即可实现对数据库的访问和操作。它提供了包括增删改查等在内的常⽤功能!学习并使⽤Spring Data JPA 可以极⼤提⾼开发效率。
说明:Spring Data JPA 极⼤简化了数据访问层代码。
如何简化呢?使⽤了Spring Data JPA,我们Dao层中只需要写接⼝,不需要写实现类,就⾃动具有了增删改查、分⻚查询等⽅法。使⽤Spring Data JPA 很多场景下不需要我们⾃⼰写sql语句。
构建⼯程
<dependencies>
<dependency>
<groupId>junitgroupId>
<artifactId>junitartifactId>
<version>4.12version>
<scope>testscope>
dependency>
<dependency>
<groupId>org.springframework.datagroupId>
<artifactId>spring-data-jpaartifactId>
<version>2.1.8.RELEASEversion>
dependency>
<dependency>
<groupId>javax.elgroupId>
<artifactId>javax.el-apiartifactId>
<version>3.0.1-b04version>
dependency>
<dependency>
<groupId>org.glassfish.webgroupId>
<artifactId>javax.elartifactId>
<version>2.2.6version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-aopartifactId>
<version>5.1.12.RELEASEversion>
dependency>
<dependency>
<groupId>org.aspectjgroupId>
<artifactId>aspectjweaverartifactId>
<version>1.8.13version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-contextartifactId>
<version>5.1.12.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-context-supportartifactId>
<version>5.1.12.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-ormartifactId>
<version>5.1.12.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-beansartifactId>
<version>5.1.12.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-coreartifactId>
<version>5.1.12.RELEASEversion>
dependency>
<dependency>
<groupId>org.hibernategroupId>
<artifactId>hibernate-coreartifactId>
<version>5.4.0.Finalversion>
dependency>
<dependency>
<groupId>org.hibernategroupId>
<artifactId>hibernate-entitymanagerartifactId>
<version>5.4.0.Finalversion>
dependency>
<dependency>
<groupId>org.hibernategroupId>
<artifactId>hibernate-validatorartifactId>
<version>5.4.0.Finalversion>
dependency>
<dependency>
<groupId>mysqlgroupId>
<artifactId>mysql-connector-javaartifactId>
<version>5.1.46version>
dependency>
<dependency>
<groupId>com.alibabagroupId>
<artifactId>druidartifactId>
<version>1.1.21version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-testartifactId>
<version>5.1.12.RELEASEversion>
dependency>
dependencies>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
https://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/data/jpa
https://www.springframework.org/schema/data/jpa/spring-jpa.xsd
">
<context:property-placeholder
location="classpath:jdbc.properties"/>
<bean id="dataSource"
class="com.alibaba.druid.pool.DruidDataSource">
<property name="driverClassName" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
bean>
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
>
<property name="dataSource" ref="dataSource"/>
<property name="packagesToScan"
value="com.lagou.edu.pojo"/>
<property name="persistenceProvider">
<bean
class="org.hibernate.jpa.HibernatePersistenceProvider">bean>
property>
<property name="jpaDialect">
<bean
class="org.springframework.orm.jpa.vendor.HibernateJpaDialect">bean>
property>
<property name="jpaVendorAdapter" >
<bean
class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<property name="generateDdl" value="false"/>
<property name="database" value="MYSQL"/>
<property name="databasePlatform"
value="org.hibernate.dialect.MySQLDialect"/>
<property name="showSql" value="true"/>
bean>
property>
bean>
<jpa:repositories base-package="com.lagou.edu.dao" entity-manager-
factory-ref="entityManagerFactory"
transaction-manager-ref="transactionManager"/>
<bean id="transactionManager"
class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory"/>
bean>
<context:component-scan base-package="com.lagou.edu"/>
beans>
package com.lagou.edu.pojo;
import javax.persistence.*;
/**
* 简历实体类(在类中要使⽤注解建⽴实体类和数据表之间的映射关系以及属性和字段的映射关系)
* 1、实体类和数据表映射关系
* @Entity
* @Table
* 2、实体类属性和表字段的映射关系
* @Id 标识主键
* @GeneratedValue 标识主键的⽣成策略
* @Column 建⽴属性和字段映射
*/
@Entity
@Table(name = "tb_resume")
public class Resume {
@Id
/**
* ⽣成策略经常使⽤的两种:
* GenerationType.IDENTITY:依赖数据库中主键⾃增功能 Mysql
* GenerationType.SEQUENCE:依靠序列来产⽣主键 Oracle
* */
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private Long id;
@Column(name = "name")
private String name;
@Column(name = "address")
private String address;
@Column(name = "phone")
private String phone;
//get、set方法忽略
}
package com.lagou.edu.dao;
import com.lagou.edu.pojo.Resume;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.jpa.repository.Query;
import java.util.List;
/**
* ⼀个符合SpringDataJpa要求的Dao层接⼝是需要继承JpaRepository和
JpaSpecificationExecutor
*
* JpaRepository<操作的实体类类型,主键类型>
* 封装了基本的CRUD操作
*
* JpaSpecificationExecutor<操作的实体类类型>
* 封装了复杂的查询(分⻚、排序等)
*
*/
public interface ResumeDao extends JpaRepository<Resume,Long>,
JpaSpecificationExecutor<Resume> {
@Query("from Resume where id=?1 and name=?2")
public List<Resume> findByJpql(Long id,String name);
/**
* 使⽤原⽣sql语句查询,需要将nativeQuery属性设置为true,默认为false(jpql)
* @param name
* @param address
* @return
*/
@Query(value = "select * from tb_resume where name like ?1 and
address like ?2",nativeQuery = true)
public List<Resume> findBySql(String name,String address);
/**
* ⽅法命名规则查询
* 按照name模糊查询(like)
* ⽅法名以findBy开头
* -属性名(⾸字⺟⼤写)
* -查询⽅式(模糊查询、等价查询),如果不写查询⽅式,默认等价
查询
*/
public List<Resume> findByNameLikeAndAddress(String name,String
address);
}