java+ssm 基础

首先说以下我的开发工具是：IDEA+mysql      简单的“SSM“框架建设，第一次写的时候到jar包的时候把自己弄得很糊涂，希望此代码可以对你们有帮助。下来贴出的我项目的包位置，![这是Dao，service，controller]

引用块内容

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访问URL:localhost:8080/insertUser.do

下来才是真正的干货，首先建一个entity实体User类：

package com.demo.entity;public class UserEntity {    //id    private Integer id;    //名称    private String userName;    //密码    private String userPwd;    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public String getUserName() {        return userName;    }    public void setUserName(String userName) {        this.userName = userName;    }    public String getUserPwd() {        return userPwd;    }    public void setUserPwd(String userPwd) {        this.userPwd = userPwd;    }    @Override    public String toString() {        return "UserEntity{" + "id=" + id + ", userName='" + userName + '\'' + ", userPwd='" + userPwd + '\'' + '}';    }}

下来就是Dao了，提个建议：这里的方法名和mapper里要一致，并且最好能统一点，等你的实体多了你可以将其抽成一个基础借口，让其它的去集成就行了，这样可以减轻您的代码体积和代码量。

package com.demo.dao;import com.demo.entity.UserEntity;/** * 用户信息数据层 * */public interface UserDao {    //新增用户信息    int insertUser(UserEntity userEntity);    //修改用户信息    int updateUser(UserEntity userEntity);    //查询用户信息    UserEntity findUser(UserEntity userEntity);    //删除用户信息    int deleteUser(Integer id);}接下来就到service接口和serviceImpl类了，实现类里面一定要多判断，不然你在执行Dao时，就会出现很多Exception，这些都是可以避免的。建议多用接口这样你需求有变化时，你的代码改动量时最小的而且不会出现“跷跷板”情况。

package com.demo.service;

import com.demo.entity.UserEntity;

/**
* 用户信息业务逻辑处理层
**/
public interface UserService {

//新增用户信息String insertUser(UserEntity userEntity);//修改用户信息String updateUser(UserEntity userEntity);//查询用户信息UserEntity findUser(UserEntity userEntity);//删除用户信息String deleteUser(Integer id);

}
serviceImpl实现类：我在这个类里面，验证如果出现异常就自己new一个RunTimeException这样的好处是唇线异常信息是不是是服务器停止。而且对于前端也好判断，你可以自己写一个异常类继承Exception。

package com.demo.service.impl;import com.demo.dao.UserDao;import com.demo.entity.UserEntity;import com.demo.service.UserService;import org.springframework.stereotype.Service;import javax.annotation.Resource;/** * 业务逻辑处理实现类 **//*controller依赖注入service接口时,如果项目的service接口多,建议使用别名。这样可以规避掉一些不必要的异常*/@Service("userServices")public class UserServiceImpl implements UserService {    @Resource    private UserDao userDao;    /*新增用户信息*/    public String insertUser(UserEntity userEntity) {       //验证参数有效性        if(userEntity==null){            throw new RuntimeException("新增对象不能为空...");        }else if(userEntity.getUserName()==null || userEntity.getUserName().equals("")){            throw new RuntimeException("用户名称不能为空...");        }else if(userEntity.getUserPwd()==null || userEntity.getUserPwd().equals("")){            throw new RuntimeException("用户密码不能为空...");        }        //执行新增        int rows = userDao.insertUser(userEntity);        //根据记过判断是否新增成功        if(rows==-1){            throw new RuntimeException("新增失败..");        }        return "新增成功";    }    /*修改用户信息*/    public String updateUser(UserEntity userEntity) {        //验证参数有效性        if(userEntity==null){            throw new RuntimeException("新增对象不能为空...");        }else if( userEntity.getId().equals("")||userEntity.getId()==null){            throw new RuntimeException("用户id不能为空...");        }else if(userEntity.getUserName()==null || userEntity.getUserName().equals("")){            throw new RuntimeException("用户名称不能为空...");        }else if(userEntity.getUserPwd()==null || userEntity.getUserPwd().equals("")){            throw new RuntimeException("用户密码不能为空...");        }        //执行新增        int rows = userDao.updateUser(userEntity);        //根据记过判断是否新增成功        if(rows==-1){            throw new RuntimeException("修改失败..");        }        return "修改成功";    }    /*查询*/    public UserEntity findUser(UserEntity userEntity) {        //执行查询        UserEntity entity = userDao.findUser(userEntity);        //根据查询结果判断是否有数据        if(entity==null){            throw new RuntimeException("没有数据对象...");        }        return entity;    }

最后就是controller和controllerImpl了：

package com.demo.controller;import com.demo.entity.UserEntity;public interface UserController {    //新增用户信息    String insertUser(UserEntity userEntity);    //修改用户信息    String updateUser(UserEntity userEntity);    //查询用户信息    UserEntity findUser(UserEntity userEntity);    //删除用户信息    String deleteUser(Integer id);}

controllerImpl实现类：

package com.demo.controller.impl;import com.demo.controller.UserController;import com.demo.entity.UserEntity;import com.demo.service.UserService;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;import javax.annotation.Resource;@Controller@RequestMapping("/")public class UserControllerimpl implements UserController {    @Resource    private UserService userService;    /*新增用户信息*/    @RequestMapping("insertUser")    @ResponseBody    public String insertUser(UserEntity userEntity) {        //执行新增        String str = userService.insertUser(userEntity);        //返回结果对象        return str;    }    /*修改用户信息*/    @RequestMapping("updateUser")    @ResponseBody    public String updateUser(UserEntity userEntity) {        //执行修改        String str = userService.updateUser(userEntity);        //返回结果对象        return str;    }    /*查询用户信息*/    @RequestMapping("findUser")    @ResponseBody    public UserEntity findUser(UserEntity userEntity) {        //执行新增        UserEntity entity = userService.findUser(userEntity);        //返回结果对象        return entity;    }    @RequestMapping("deleteUser")    @ResponseBody    public String deleteUser(Integer id) {        //执行新增        String str = userService.deleteUser(id);        //返回结果对象        return str;    }}

下来就是配置文件了：
mapper文件：

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" ><mapper namespace="com.demo.dao.UserDao"><!--新增用户信息--><insert id="insertUser" parameterType="com.demo.entity.UserEntity">    INSERT INTO (    user_name,    user_pwd)VALUES(    #{userName},    #{userPwd})<!--修改用户信息--><insert id="updatetUser" parameterType="com.demo.entity.UserEntity">     UPDATE user        <trim prefix="set" suffixOverrides=",">            <if test="userName!=null and !userName.equals('')">                user_name=#{userName},            </if>            <if test="userPwd!=null and !userPwd.equals('')">                user_pwd=#{userPwd},            </if></trim>        WHERE id=#{id};<!--删除表中信息-->    <update id="deleteUser" parameterType="com.demo.entity.UserEntity">       DELETE       FROM user        WHERE id=#{id}    </update><!--查询所有用户信息分页-->    <select id="findUser" parameterType="com.demo.entity.UserEntity"            resultType="com.demo.entity.UserEntity">        SELECT id,user_name,user_pwd        FROM user;</mapper>

mysql数据库链接：

driverClasss=com.mysql.jdbc.DriverjdbcUrl=jdbc:mysql://localhost:3306/"数据库连接名"?useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNullusername=rootpassword=123456initialSize=0maxActive=20maxIdle=20minIdle=1maxWait=60000

spring-mvc配置文件：

<?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:p="http://www.springframework.org/schema/p"       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-4.0.xsd                        http://www.springframework.org/schema/mvc                        http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">    <!-- 自动扫描  @Controller-->    <context:component-scan base-package="com.demo"/>    <!--避免IE执行AJAX时，返回JSON出现下载文件 -->    <bean id="mappingJacksonHttpMessageConverter"          class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">        <property name="supportedMediaTypes">            <list>                <value>text/html;charset=UTF-8</value>            </list>        </property>    </bean>    <!-- 启动SpringMVC的注解功能，完成请求和注解POJO的映射 -->    <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">        <property name="messageConverters">            <list>                <ref bean="mappingJacksonHttpMessageConverter"/> <!-- JSON转换器 -->            </list>        </property>    </bean></beans>

spring-mybatis：

<?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:tx="http://www.springframework.org/schema/tx"       xsi:schemaLocation="http://www.springframework.org/schema/beans                        http://www.springframework.org/schema/beans/spring-beans-3.1.xsd                        http://www.springframework.org/schema/context                        http://www.springframework.org/schema/context/spring-context-3.1.xsd                        http://www.springframework.org/schema/tx                        http://www.springframework.org/schema/tx/spring-tx.xsd">    <!-- 自动扫描 -->    <context:component-scan base-package="com.demo"/>    <!-- 第一种方式：加载一个properties文件 -->    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">        <property name="location" value="classpath:jdbc.properties"/>    </bean>    <!-- 第二种方式：加载多个properties文件    <bean id="configProperties" class="org.springframework.beans.factory.config.PropertiesFactoryBean">        <property name="locations">            <list>                <value>classpath:jdbc.properties</value>                <value>classpath:common.properties</value>            </list>        </property>        <property name="fileEncoding" value="UTF-8"/>    </bean>    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PreferencesPlaceholderConfigurer">        <property name="properties" ref="configProperties"/>    </bean>    -->    <!-- 配置数据源 -->    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"          destroy-method="close">        <property name="driverClassName" value="${driverClasss}"/>        <property name="url" value="${jdbcUrl}"/>        <property name="username" value="${username}"/>        <property name="password" value="${password}"/>        <!-- 初始化连接大小 -->        <property name="initialSize" value="${initialSize}"></property>        <!-- 连接池最大数量 -->        <property name="maxActive" value="${maxActive}"></property>        <!-- 连接池最大空闲 -->        <property name="maxIdle" value="${maxIdle}"></property>        <!-- 连接池最小空闲 -->        <property name="minIdle" value="${minIdle}"></property>        <!-- 获取连接最大等待时间 -->        <property name="maxWait" value="${maxWait}"></property>    </bean>    <!-- mybatis和spring完美整合，不需要mybatis的配置映射文件 -->    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">        <property name="dataSource" ref="dataSource"/>        <!-- 自动扫描mapping.xml文件 -->        <property name="mapperLocations" value="classpath:mapping/*.xml"></property>        <property name="configLocation" value="classpath:mybatis-config.xml"></property>    </bean>    <!-- DAO接口所在包名，Spring会自动查找其下的类 -->    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">        <property name="basePackage" value="com.demo"/>        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>    </bean>    <!-- (事务管理)transaction manager, use JtaTransactionManager for global tx -->    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">        <property name="dataSource" ref="dataSource"/>    </bean>    <!-- (事务管理)transaction manager, use JtaTransactionManager for global tx -->    <tx:annotation-driven transaction-manager="transactionManager"/></beans>

最后就是web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns="http://java.sun.com/xml/ns/javaee"         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee          http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"         version="3.0">    <display-name>demo</display-name>    <!-- 编码过滤器 -->    <filter>        <filter-name>encodingFilter</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>encodingFilter</filter-name>        <url-pattern>/*</url-pattern>    </filter-mapping>    <!-- spring监听器 -->    <listener>        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>    </listener>    <!-- 防止spring内存溢出监听器，比如quartz -->    <listener>        <listener-class>org.springframework.web.util.IntrospectorCleanupListener</listener-class>    </listener>    <!-- spring mvc servlet-->    <servlet>        <servlet-name>SpringMVC</servlet-name>        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>        <init-param>            <param-name>contextConfigLocation</param-name>            <param-value>classpath:spring-mvc.xml</param-value>        </init-param>        <load-on-startup>1</load-on-startup>        <async-supported>true</async-supported>    </servlet>    <servlet-mapping>        <servlet-name>SpringMVC</servlet-name>        <!-- 此处也可以配置成 *.do 形式 -->        <url-pattern>*.do</url-pattern>    </servlet-mapping></web-app>