SSM框架项目实践 二分搜索树

于 2022-10-16 18:17:20 发布
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分类专栏： 日志 文章标签： java spring 开发语言 算法
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本文链接：https://blog.youkuaiyun.com/sdfsdfsdds2/article/details/127350519

学习目标：

需求分析与SSM环境准备（上）

学习二分搜索树删除最大元素与最小元素

学习内容：

Spring与SpringMVC环境准备，解决请求与响应乱码问题，完成Spring与Mybatis的整合，继承Junit单元测试与Logback日志。代码如下：

pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>imooc-reader</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <repositories>
        <repository>
            <id>aliyun</id>
            <name>aliyun</name>
            <url>https://maven.aliyun.com/repository/public</url>
        </repository>
    </repositories>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.3.8</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.12.3</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.3.8</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.7</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.6</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.27</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.13-SNSAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.3.8</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.3</version>
        </dependency>
    </dependencies>

</project>

applicationContext.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:task="http://www.springframework.org/schema/task"
       xsi:schemaLocation="
            http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/context
            http://www.springframework.org/schema/context/spring-context.xsd
            http://www.springframework.org/schema/task
            http://www.springframework.org/schema/task/spring-task.xsd
            http://www.springframework.org/schema/mvc
            http://www.springframework.org/schema/mvc/spring-mvc.xsd">
    <context:component-scan base-package="com.imooc"/>
    <mvc:annotation-driven>
        <mvc:message-converters>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="supportedMediaTypes">
                    <list>
                        <value>application/json;charset=utf-8</value>
                    </list>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>
    <mvc:default-servlet-handler/>
<!--    MyBatis与Spring的整合配置-->
<!--    1.配置数据源-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/imooc_reader?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8&amp;serverTimezone=Asia/Shanghai&amp;allowPublicKeyRetrieval=true"/>
        <property name="username" value="root"/>
        <property name="password" value="zjh123"/>
        <property name="initialSize" value="5"/>
        <property name="maxActive" value="20"/>
    </bean>
<!--    2.配置Session与FactoryBean-->
    <bean id="sessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="mapperLocations" value="classpath:mappers/*.xml"/>
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
    </bean>
<!--    3.配置Mapper扫描器-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.imooc.reader.mapper"/>
    </bean>
</beans>

web.xml:

<?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_3_1.xsd"
         version="3.1">
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
    </welcome-file-list>
    <servlet>
        <servlet-name>spring-mvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:applicationContext*.xml</param-value>
        </init-param>
        <load-on-startup>0</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>spring-mvc</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <filter>
        <filter-name>characterFilter</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>characterFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

mybatis-config.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
</configuration>

logback.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<configuration>
    <appender name="console" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <pattern>[%thread] %d %level %logger{10} -%msg%n</pattern>
            <charset>UTF-8</charset>
        </encoder>
    </appender>
<!--    <appender name="accessHistoryLog" class="ch.qos.logback.core.rolling.RollingFileAppender">-->
<!--        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">-->
<!--            <fileNamePattern>d:/logs/history.%d.log</fileNamePattern>-->
<!--        </rollingPolicy>-->
<!--        <encoder>-->
<!--            <pattern>[%thread] %d %level %logger{10} -%msg%n</pattern>-->
<!--        </encoder>-->
<!--    </appender>-->
    <root level="debug">
        <appender-ref ref="console"/>
    </root>
<!--    <logger name="com.imooc.restful.interceptor.AccessHistoryInterceptor" level="INFO" additivity="false">-->
<!--        <appender-ref ref="accessHistoryLog"/>-->
<!--    </logger>-->
</configuration>

二分搜索树：

import com.sun.corba.se.impl.resolver.SplitLocalResolverImpl;

import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;

public class BST<E extends Comparable<E>> {
    private class Node {
        public E e;
        public Node left, right;

        public Node(E e) {
            this.e = e;
            left = null;
            right = null;
        }
    }

    private Node root;
    private int size;

    public BST() {
        root = null;
        size = 0;
    }

    public int size() {
        return size;
    }

    public boolean isEmpty() {
        return size == 0;
    }

    //向二分搜索树中添加新的元素e
    public void add(E e) {
        root = add(root, e);
    }

    //向以node为根的二分搜索树中插入元素E，递归算法
    //返回插入节点后二分搜索树的根
    private Node add(Node node, E e) {

        if (node == null) {
            size++;
            return new Node(e);
        }
        if (e.compareTo(node.e) < 0) {
            node.left = add(node.left, e);
        } else if (e.compareTo(node.e) > 0)
            node.right = add(node.right, e);
        return node;
    }

    //看二分搜索树中是否包含元素e
    public boolean contains(E e) {
        return contains(root, e);
    }

    //以node为根的二分搜索树中是否包含元素e,递归算法
    private boolean contains(Node node, E e) {
        if (node == null)
            return false;
        if (e.compareTo(node.e) == 0)
            return true;
        else if (e.compareTo(node.e) < 0)
            return contains(node.left, e);
        else
            return contains(node.right, e);
    }

    //二分搜索树的前序遍历
    public void preOrder() {
        preOrder(root);
    }

    //前序遍历以node为根的二分搜索树，递归算法
    private void preOrder(Node node) {
        if (node == null)
            return;
        System.out.println(node.e);
        preOrder(node.left);
        preOrder(node.right);
    }

    //二分搜索树的非递归前序遍历
    public void preOrderNR() {
        Stack<Node> stack = new Stack<>();
        stack.push(root);
        while (!stack.isEmpty()){
            Node cur = stack.pop();
            System.out.println(cur.e);
            if(cur.right!=null)
                stack.push(cur.right);
            if (cur.left != null)
                stack.push(cur.left);
        }
    }

    //二分搜索树的中序遍历
    public void inOrder() {
        inOrder(root);
    }

    //中序遍历以node为根的二分搜索树，递归算法
    private void inOrder(Node node) {
        if (node == null) {
            return;
        }
        inOrder(node.left);
        System.out.println(node.e);
        inOrder(node.right);
    }

    //二分搜索树的后序遍历
    public void postOrder() {
        postOrder(root);
    }
    //后序遍历以node为根的二分搜索树，递归算法
    private void postOrder(Node node){
        if(node==null){
            return;
        }
        postOrder(node.left);
        postOrder(node.right);
        System.out.println(node.e);
    }
    //二分搜索树的层序遍历
    public void levelOrder(){
        Queue<Node> q = new LinkedList<>();
        q.add(root);
        while (!q.isEmpty()) {
            Node cur = q.remove();
            System.out.println(cur.e);
            if (cur.left != null)
                q.add(cur.left);
            if (cur.right != null)
                q.add(cur.right);
        }
    }
    //寻找二分搜索树的最小元素
    public E minimum(){
        if (size == 0)
            throw new IllegalArgumentException("BST is empty!");
        return minimum(root).e;
    }
    //返回以node为根的二分搜索树的最小值所在的节点
    private Node minimum(Node node){
        if(node.left==null)
            return node;
        return minimum(node.left);
    }
    //寻找二分搜索树的最大元素
    public E maximum(){
        if (size == 0)
            throw new IllegalArgumentException("BST is empty!");
        return maximum(root).e;
    }
    //返回以node为根的二分搜索树的最大值所在的节点
    private Node maximum(Node node){
        if(node.right==null)
            return node;
        return minimum(node.right);
    }
    //从二分搜索树中删除最小值所在的节点，返回最小值
    public E removeMin(){
        E ret = minimum();
        root=removeMin(root);
        return ret;
    }

    //删除掉以node为根的二分搜索树中的最小节点
    //返回删除节点后新的二分搜索树的根
    private Node removeMin(Node node){
        if(node.left==null){
            Node rightNode=node.right;
            node.right=null;
            size--;
            return rightNode;
        }
        node.left = removeMin(node.left);
        return node;
    }
    //从二分搜索树中删除最大值所在的节点，返回最小值
    public E removeMax(){
        E ret = maximum();
        root=removeMax(root);
        return ret;
    }

    //删除掉以node为根的二分搜索树中的最大节点
    //返回删除节点后新的二分搜索树的根
    private Node removeMax(Node node){
        if(node.right==null){
            Node leftNode=node.left;
            node.left=null;
            size--;
            return leftNode;
        }
        node.right = removeMax(node.right);
        return node;
    }
    @Override
    public String toString() {
        StringBuilder res = new StringBuilder();
        generateBSTString(root, 0, res);
        return res.toString();
    }

    //生成以node为根节点，深度为depth的描述二叉树的字符串
    private void generateBSTString(Node node, int depth, StringBuilder res) {
        if (node == null) {
            res.append(generateDepthString(depth) + "null\n");
            return;
        }
        res.append(generateDepthString(depth) + node.e + "\n");
        generateBSTString(node.left, depth + 1, res);
        generateBSTString(node.right, depth + 1, res);
    }

    private String generateDepthString(int depth) {
        StringBuilder res = new StringBuilder();
        for (int i = 0; i < depth; i++) {
            res.append("--");
        }
        return res.toString();
    }

}

学习时间：

08:30-10:30 11:30-12:30 15:00-16:00

学习产出：

对于SSM框架的环境准备进行了系统的学习，同时学会了Spring与Mybatis的整合，对于以后基于SSM框架的开发有了一定的经验。

对于二分搜索树删除最大值和最小值进行了代码的实现，对于明天学习在二分搜索树中删除任意一个元素打下了基础。

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