本次主要是从基础开始配置SpringMVC,包括环境搭建,参数传递,返回值,重定向等细节的讲解。当然最后还会实现对Mysql名为“test”数据库的“jvm”表的增删改查。
SpringMVC的配置
项目准备
我用的是IDEA,首先新建一个WebApplication项目,然后到入jar包,
接着配置一个Tomcat用来启动项目,需要注意的是,你需要在Project Structure->Artifacts的里面添加热部署,(我的默认有一个war exploded)在deployment里面将右边的jar包全选后右击put into web lib的下面。当然后面还会用的jstl和servelt.api这两个jar包,你可以一起导入。
包结构设计
这里主要讲一下spring-mvc.xml的内容,它是一个spring的配置文件,新建是可以在XML Configuration File->Spring Config里面新建文件。需要加一些语句,包扫描声明以及识别mvc注解。里面还需建一个bean对象,是视图解析器,添加返回值路径前缀与后缀。
之后,我们就要在web.xml声明MVC请求中的DispatcherServlet。
Controller
控制器首先要定义@controller注解和@RequestMapping注解。
-
对于参数传递可以写在函数后面用@PathVariable声明–变量名要和jsp定义的input名相同或者跟在RequestMapping里面用{
}指定。 -
返回值可以直接返回一个string字符串,之前spring-mvc.xml里面解析会给字符串加上前后缀补全路径。
-
重定向只需返回一个redirect,例如return “redirect:/jvm/test”。
这里有一个方便的处理前端显示后端的数据,一是函数返回String类型,通过定义ModelMap modelMap对象,只要通过modelMap.addAtributes(“名称”,entity对象),返回entity对象名就可以了,二是返回ModelAndView对象,定义一个ModelAndView model对象,通过model.addObject(“名称”,entity对象),返回model就可以了-----前端就可以用js标签${jvm.id}取到值了
项目目录
下面是代码部分:
controller.JvmController
package top.jff.connector.controller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import top.jff.connector.entity.Jvm;
import top.jff.connector.service.JvmServiceImpl;
import javax.servlet.http.HttpServletRequest;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
@Controller
@RequestMapping("jvm")
public class JvmController {
@RequestMapping(value = "/insert")
public String insert(Jvm jvm){
int id=jvm.getId();
int instances=jvm.getInstances();
int bytes=jvm.getBytes();
String class_name=jvm.getClass_name();
int num=jvm.getNum();
JvmServiceImpl jvmService=new JvmServiceImpl();
jvmService.insert(id,instances,bytes ,class_name ,num );
return "success";
}
@RequestMapping(value = "/find")
public String find(int id,ModelMap modelMap){
JvmServiceImpl jvmService=new JvmServiceImpl();
Jvm jvm=new Jvm();
jvm=jvmService.find(id);
modelMap.addAttribute("jvm",jvm);
return "jvm";
}
}
entity.Jvm
package top.jff.connector.entity;
public class Jvm {
private int id;
private int instances;
private int bytes;
private String class_name;
private int num;
public int getId() {
return id;
}
public int getInstances() {
return instances;
}
public int getBytes() {
return bytes;
}
public String getClass_name() {
return class_name;
}
public int getNum() {
return num;
}
public void setId(int id) {
this.id = id;
}
public void setInstances(int instances) {
this.instances = instances;
}
public void setBytes(int bytes) {
this.bytes = bytes;
}
public void setClass_name(String class_name) {
this.class_name = class_name;
}
public void setNum(int num) {
this.num = num;
}
}
service.JvmService
package top.jff.connector.service;
import top.jff.connector.entity.Jvm;
public interface JvmService {
public void insert(int id,int stances,int bytes,String class_name,int num);
public Jvm find(int id);
}
service.JvmServiceImpl
package top.jff.connector.service;
import top.jff.connector.entity.Jvm;
import java.sql.*;
public class JvmServiceImpl implements JvmService{
@Override
public void insert(int id,int instances,int bytes,String class_name,int num){
String sql="insert into jvm(id,instances,bytes,class_name,num) values(?,?,?,?,?)";
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
// 数据库连接字符串
String url = "jdbc:mysql://localhost:3308/test?useUnicode=true&characterEncoding=utf-8";
// 数据库用户名
String username = "root";
// 数据库密码
String password = "123456";
// 创建Connection连接
try {
Connection conn = null;
conn = DriverManager.getConnection(url, username, password);
PreparedStatement preparedStatement= null;
preparedStatement = conn.prepareStatement(sql);
preparedStatement.setInt(1,id );
preparedStatement.setInt(2,instances );
preparedStatement.setInt(3,bytes);
preparedStatement.setString(4,class_name );
preparedStatement.setInt(5,num );
preparedStatement.execute();
System.out.println("插入成功");
} catch (SQLException e) {
System.out.println("错误");
e.printStackTrace();
}
}
@Override
public Jvm find(int id){
Jvm jvm=new Jvm();
String sql="select * from jvm where id=?";
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
String url = "jdbc:mysql://localhost:3308/test?useUnicode=true&characterEncoding=utf-8";
// 数据库用户名
String username = "root";
// 数据库密码
String password = "123456";
try {
Connection connection=DriverManager.getConnection(url, username, password);
PreparedStatement preparedStatement=connection.prepareStatement(sql);
ResultSet resultSet=preparedStatement.executeQuery();
while (resultSet.next()){
jvm.setId(resultSet.getInt(1));
jvm.setInstances(resultSet.getInt(2));
jvm.setBytes(resultSet.getInt(3));
jvm.setClass_name(resultSet.getString(4));
jvm.setNum(resultSet.getInt(5));
}
} catch (SQLException e) {
e.printStackTrace();
}
return jvm;
}
}
jsp页面
index.jsp
<%--
Created by IntelliJ IDEA.
User: JFF
Date: 2020/5/16
Time: 5:17
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>$Title$</title>
</head>
<body>
<form action="/jvm/insert" method="post">
<input type="text" name="id" />
<input type="text" name="instances" />
<input type="text" name="bytes" />
<input type="text" name="class_name" />
<input type="text" name="num" />
<input type="submit" value="提交mvc" />
</form>
<form action="/jvm/find" method="post">
<input type="text" name="id"/>
<input type="submit" value="查询"/>
</form>
</body>
</html>
jvm.jsp
<%--
Created by IntelliJ IDEA.
User: JFF
Date: 2020/5/16
Time: 5:10
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
success ${jvm.id} ${jvm.instances} ${jvm.bytes} ${jvm.class_name} ${jvm.num}
</body>
</html>
两个配置文件需要特特特别注意
web.xml-----为DispatcherServlet创建入口
<?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">
<servlet>
<servlet-name>ssm-blog</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:./top/jff/connector/resource/spring-mvc.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>ssm-blog</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
resource.spring-mvc.xml–包扫描,识别注解,定义视图解析bean对象
<?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-4.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">
<mvc:annotation-driven/>
<context:component-scan base-package="top.jff.connector.**"></context:component-scan>
<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/"/>
<property name="suffix" value=".jsp"/>
<property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
</bean>
</beans>
终于写完了,如果有什么不完善的地方,还请各位指教。需要完整jar包的可以留言。