SpringMVC_java_内存溢出

简介
Spring MVC属于SpringFrameWork的后续产品，已经融合在Spring Web Flow里面。Spring 框架提供了构建 Web 应用程序的全功能 MVC 模块。使用 Spring 可插入的 MVC 架构，从而在使用Spring进行WEB开发时，可以选择使用Spring的Spring MVC框架或集成其他MVC开发框架，如Struts1(现在一般不用)，Struts 2(一般老项目使用)等等。

原理篇

代码
Maven依赖

    <dependencies>
        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
            <version>4.12version>
        dependency>
        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-webmvcartifactId>
            <version>5.1.9.RELEASEversion>
        dependency>
        <dependency>
            <groupId>javax.servletgroupId>
            <artifactId>servlet-apiartifactId>
            <version>2.5version>
        dependency>
        <dependency>
            <groupId>javax.servlet.jspgroupId>
            <artifactId>jsp-apiartifactId>
            <version>2.2version>
        dependency>
        <dependency>
            <groupId>javax.servletgroupId>
            <artifactId>jstlartifactId>
            <version>1.2version>
        dependency>
    dependencies>

web.xml


<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>springmvcservlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>

        <init-param>
            <param-name>contextConfigLocationparam-name>
            <param-value>classpath:springmvc-servlet.xmlparam-value>
        init-param>

        <load-on-startup>1load-on-startup>
    servlet>
    
    <servlet-mapping>
        <servlet-name>springmvcservlet-name>



        <url-pattern>/url-pattern>
    servlet-mapping>

web-app>

springmvc-servlet.xml


<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
        https://www.springframework.org/schema/beans/spring-beans.xsd">




    <bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>

    <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>


    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">

        <property name="prefix" value="/WEB-INF/jsp/"/>

        <property name="suffix" value=".jsp"/>
    bean>


    <bean id="/hello" class="com.cai.controller.HelloController"/>
beans>

HelloController类

package com.cai.controller;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

// 实现Controller 导mvc包
public class HelloController implements Controller {
    @Override
    public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        // ModelAndView 模型和视图
        ModelAndView mv = new ModelAndView();

        // 调用业务层
        String result = "HelloSpringMVC";

        // 封装对象，放在ModelAndView中。Model
        mv.addObject("msg", result);
        // 封装要跳转的视图 放在ModelAndView中
        mv.setViewName("hello"); //: /WEB-INF/jsp/hello.jsp
        return mv;
    }
}

hello.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Titletitle>
head>
<body>

${msg}

body>
html>

可能遇到报错添加lib文件夹导入依赖

注解篇

代码
web.xml


<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>springmvcservlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
        
        <init-param>
            <param-name>contextConfigLocationparam-name>
            <param-value>classpath:springmvc-servlet.xmlparam-value>
        init-param>
        
        <load-on-startup>1load-on-startup>
    servlet>

    <servlet-mapping>
        <servlet-name>springmvcservlet-name>
        
        
        
        <url-pattern>/url-pattern>
    servlet-mapping>

web-app>

springmvc-servlet.xml


<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
        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/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">


    <context:component-scan base-package="com.cai.controller"/>

    <mvc:default-servlet-handler/>

    <mvc:annotation-driven/>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    bean>

beans>

hello.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Titletitle>
head>
<body>

${msg}

body>
html>

HelloController类

package com.cai.controller;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller //不在需要自己配bean
@RequestMapping("/hello")
public class HelloController {

    @RequestMapping("/h1")
    public String hello(Model model) {
        // 封装数据
        model.addAttribute("msg", "Hello SpringMVCAnnotation!");
        return "hello"; // 会被视图解析器处理
    }
}

接收请求参数

// @RequestParam 约束请求参数 localhos:8080/user/t1?username=xx
@GetMapping("/t1")
public String test1(@RequestParam("username") String name, Model model){
    System.out.println("接收到前端的参数为:"+name);

    model.addAttribute("msg", name);

    return "hello";
}

乱码解决


<filter>
    <filter-name>characterEncodingFilterfilter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilterfilter-class>
    
    <init-param>
        <param-name>encodingparam-name>
        <param-value>UTF-8param-value>
    init-param>
filter>
<filter-mapping>
    <filter-name>characterEncodingFilterfilter-name>
    <url-pattern>/*url-pattern>
filter-mapping>

Json 前端demo jsontest.html

doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Documenttitle>

    <script type="text/javascript">
        // 编写一个JavaScript对象 ES6
        var user = {
            name: "张三",
            age: 3,
            sex: "男"
        };
        console.log(user);

        // 将js对象转 json串
        var json = JSON.stringify(user);
        console.log(json)

        // 将json串 转js对象
        var obj = JSON.parse(json);
        console.log(obj)

    script>
head>
<body>

body>
html>

后端demo jackson

Maven 依赖

<dependencies>
    <dependency>
        <groupId>com.fasterxml.jackson.coregroupId>
        <artifactId>jackson-databindartifactId>
        <version>2.10.0version>
    dependency>
    <dependency>
        <groupId>org.projectlombokgroupId>
        <artifactId>lombokartifactId>
        <version>1.16.10version>
    dependency>
dependencies>

实体类

package com.cai.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private String name;
    private int age;
    private String sex;
}

测试类

package com.cai.controller;

import com.cai.pojo.User;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import java.text.SimpleDateFormat;
import java.util.Date;

//@Controller
@RestController
public class UserController {
    
    @RequestMapping("/json1")
//    @ResponseBody //将js对象转 字符串
    public String json1() throws JsonProcessingException {
        // jackson ObjectMapper
        ObjectMapper mapper = new ObjectMapper();
        // 创建一个对象
        User user = new User("张三", 19, "男");
        // 将对象转成json串
        String str = mapper.writeValueAsString(user);
        return str;
    }

    @RequestMapping("/json2")
    public String json2() throws JsonProcessingException {

        ObjectMapper mapper = new ObjectMapper();

        Date date = new Date();

        // 时间戳 转换 能看懂的格式
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        // 将对象转成json串  1970 1.1 到现在的毫秒数 时间戳 转换格式
        return mapper.writeValueAsString(simpleDateFormat.format(date));
    }
}

解决Json乱码 spring配置


<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>

后端demo fastjson

Maven 依赖

<dependency>
    <groupId>com.alibabagroupId>
    <artifactId>fastjsonartifactId>
    <version>1.2.60version>
dependency>

    @RequestMapping("/json3")
    public String json3(){
        ArrayList<User> users = new ArrayList();
        User user = new User("张三",19,"男");
        User user2 = new User("张三2",19,"男");
        User user3 = new User("张三3",19,"男");
        users.add(user);
        users.add(user2);
        users.add(user3);
        String str = JSON.toJSONString(users);
        return str;
    }

SSM整合 Mybatis层

sql

CREATE DATABASE ssmbuild;
USE ssmbuild;
CREATE TABLE `books`(
`bookID` INT NOT NULL AUTO_INCREMENT COMMENT '书id',
`bookName` VARCHAR(100) NOT NULL COMMENT '书名',
`bookCounts` INT NOT NULL COMMENT '数量',
`detail` VARCHAR(200) NOT NULL COMMENT '描述',
KEY `bookID`(`bookID`)
)ENGINE=INNODB DEFAULT CHARSET=utf8

INSERT INTO `books`(`bookID`,`bookName`,`bookCounts`,`detail`)VALUES
(1,'Java',1,'从入门到放弃'),
(2,'MySQL',10,'从删库到跑路'),
(3,'Linux',5,'从进门到进牢')

Maven 依赖

<dependencies>
    
    <dependency>
        <groupId>junitgroupId>
        <artifactId>junitartifactId>
        <version>4.12version>
    dependency>
    
    <dependency>
        <groupId>mysqlgroupId>
        <artifactId>mysql-connector-javaartifactId>
        <version>5.1.47version>
    dependency>
    
    <dependency>
        <groupId>com.mchangegroupId>
        <artifactId>c3p0artifactId>
        <version>0.9.5.2version>
    dependency>
    
    <dependency>
        <groupId>javax.servletgroupId>
        <artifactId>servlet-apiartifactId>
        <version>2.5version>
    dependency>
    <dependency>
        <groupId>javax.servlet.jspgroupId>
        <artifactId>jsp-apiartifactId>
        <version>2.2version>
    dependency>
    <dependency>
        <groupId>javax.servletgroupId>
        <artifactId>jstlartifactId>
        <version>1.2version>
    dependency>
    
    <dependency>
        <groupId>org.mybatisgroupId>
        <artifactId>mybatisartifactId>
        <version>3.5.2version>
    dependency>
    <dependency>
        <groupId>org.mybatisgroupId>
        <artifactId>mybatis-springartifactId>
        <version>2.0.2version>
    dependency>
    
    <dependency>
        <groupId>org.springframeworkgroupId>
        <artifactId>spring-webmvcartifactId>
        <version>5.1.9.RELEASEversion>
    dependency>
    
    <dependency>
        <groupId>org.springframeworkgroupId>
        <artifactId>spring-jdbcartifactId>
        <version>5.1.9.RELEASEversion>
    dependency>
            <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <version>1.16.10version>
        dependency>
dependencies>

<build>
    <resources>
        <resource>
            <directory>src/main/javadirectory>
            <includes>
                <include>**/*.propertiesinclude>
                <include>**/*.xmlinclude>
            includes>
            <filtering>falsefiltering>
        resource>
        <resource>
            <directory>src/main/resourcesdirectory>
            <includes>
                <include>**/*.propertiesinclude>
                <include>**/*.xmlinclude>
            includes>
            <filtering>falsefiltering>
        resource>
    resources>
build>

配置

mybatis-config.xml


DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    

    <typeAliases>
        <package name="com.cai.pojo"/>
    typeAliases>

    <mappers>
        
        <mapper class="com.cai.dao.BookMapper"/>
    mappers>
configuration>

applicationContext.xml


<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
        https://www.springframework.org/schema/beans/spring-beans.xsd">

beans>

database.properties

driver=com.mysql.cj.jdbc.Driver
# mysql 8.0+ 时区配置 serverTimezone=GMT%2B8&useUnicode=true
url=jdbc:mysql://127.0.0.1:3306/ssmbuild?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true
username=root
password=root

代码

pojo 实体类

package com.cai.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Books {
    private int bookID;
    private String bookName;
    private int bookCounts;
    private String detail;
}

dao 接口

package com.cai.dao;

import com.cai.pojo.Books;
import org.apache.ibatis.annotations.Param;

import java.util.List;

public interface BookMapper {
    // 新增
    int addBook(Books books);

    // 删除
    int deleteBookById(@Param("bookID") int id);

    // 改
    int updateBook(Books books);

    // 查
    Books queryBookById(@Param("bookID") int id);

    // 查
    List<Books> queryAllBookById();
}

mapper.xml 映射


DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.cai.dao.BookMapper">
    
    <insert id="addBook" parameterType="Books">
        insert into books value (bookName,bookCounts,detail)
    insert>

    <delete id="deleteBookById" parameterType="_int">
        delete from books where bookID=#{id}
    delete>
    
    <update id="updateBook" parameterType="Books">
        update books set bookName=#{bookName},
                         bookCounts=#{bookCounts},
                         detail=#{detail}
                    where bookID=#{bookID}
    update>
    
    <select id="queryBookById" parameterType="_int" resultType="Books">
        select * from books where bookID=#{bookID}
    select>

    <select id="queryAllBookById">
        select * from books
    select>

mapper>

service 接口

package com.cai.service;

import com.cai.pojo.Books;
import org.apache.ibatis.annotations.Param;

import java.util.List;

public interface BookService {
    // 新增
    int addBook(Books books);

    // 删除
    int deleteBookById(int id);

    // 改
    int updateBook(Books books);

    // 查
    Books queryBookById(int id);

    // 查
    List<Books> queryAllBookById();
}

service 实现类

package com.cai.service;

import com.cai.dao.BookMapper;
import com.cai.pojo.Books;
import org.springframework.beans.factory.annotation.Autowired;

import java.util.List;

public class BookServiceImpl implements BookService {

    @Autowired
    private BookMapper bookMapper;

    @Override
    public int addBook(Books books) {
        return bookMapper.addBook(books);
    }

    @Override
    public int deleteBookById(int id) {
        return bookMapper.deleteBookById(id);
    }

    @Override
    public int updateBook(Books books) {
        return bookMapper.updateBook(books);
    }

    @Override
    public Books queryBookById(int id) {
        return bookMapper.queryBookById(id);
    }

    @Override
    public List<Books> queryAllBookById() {
        return bookMapper.queryAllBookById();
    }
}

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原文地址:https://www.54852.com/langs/871740.html

SpringMVC

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