Mybatis學習之自定義持久層框架（三） 自定義持久層框架：讀取並解析配置文件

創建項目工程

pom.xml文件中引入相關依賴

<?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>com.lwl</groupId>
    <artifactId>Ipersistence</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.encoding>UTF-8</maven.compiler.encoding>
        <java.version>1.8</java.version>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.17</version>
        </dependency>
        <dependency>
            <groupId>c3p0</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.1.2</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.12</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
        </dependency>
        <dependency>
            <groupId>dom4j</groupId>
            <artifactId>dom4j</artifactId>
            <version>1.6.1</version>
        </dependency>
        <dependency>
            <groupId>jaxen</groupId>
            <artifactId>jaxen</artifactId>
            <version>1.1.6</version>
        </dependency>
    </dependencies>
</project>

讀取配置文件

創建Resource類 方法 InputStream getResourceAsStream(String path)

package com.lwl.io;

import java.io.InputStream;

public class Resource {

    public static InputStream getResourceAsStream(String path){
        InputStream resourceAsStream  = Resource.class.getClassLoader().getResourceAsStream(path);
        return resourceAsStream;
    }

}

解析配置文件

創建容器對象

Congiuration 核心配置類存放sqlmapConfig.xml解析內容

package com.lwl.pojo;

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;

public class Configuration {

    /**
     * 數據庫配置
     */
    private DataSource dataSource;

    /**
     * key： statementId  value ： 封裝好的 MapperStatement
     */
    Map<String, MappedStatement> mappedStatementMap = new HashMap<>();

    public DataSource getDataSource() {
        return dataSource;
    }

    public void setDataSource(DataSource dataSource) {
        this.dataSource = dataSource;
    }

    public Map<String, MappedStatement> getMappedStatementMap() {
        return mappedStatementMap;
    }

    public void setMappedStatementMap(Map<String, MappedStatement> mappedStatementMap) {
        this.mappedStatementMap = mappedStatementMap;
    }
}

MapperStament 映射配置類 存放mapper.xml解析內容

package com.lwl.pojo;

public class MappedStatement {


    private String id;
    private String resultType;
    private String parameterType;
    private String sql;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getResultType() {
        return resultType;
    }

    public void setResultType(String resultType) {
        this.resultType = resultType;
    }

    public String getParameterType() {
        return parameterType;
    }

    public void setParameterType(String parameterType) {
        this.parameterType = parameterType;
    }

    public String getSql() {
        return sql;
    }

    public void setSql(String sql) {
        this.sql = sql;
    }
}

創建配置文件解析類

XMLConfigerBuilder 使用dom4j對配置文件進行解析 封裝到Configuration中

package com.lwl.config;

import com.lwl.io.Resource;
import com.lwl.pojo.Configuration;
import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

import java.beans.PropertyVetoException;
import java.io.InputStream;
import java.util.List;
import java.util.Properties;

public class XMLConfigerBuilder {

    private Configuration configuration;

    public XMLConfigerBuilder() {
        this.configuration = new Configuration();
    }

    /**
     * 使用dom4j對配置文件進行解析 封裝到Configuration中
     * @param in
     * @return
     */
    public Configuration parseConfig(InputStream in) throws DocumentException, PropertyVetoException {

        Document document = new SAXReader().read(in);
        Element rootElement = document.getRootElement();
        List<Element> list = rootElement.selectNodes("//property");

        Properties properties = new Properties();
        for (Element element : list) {
            String name = element.attributeValue("name");
            String value = element.attributeValue("value");
            properties.setProperty(name,value);
        }

        ComboPooledDataSource comboPooledDataSource = new ComboPooledDataSource();
        comboPooledDataSource.setDriverClass(properties.getProperty("driverClass"));
        comboPooledDataSource.setJdbcUrl(properties.getProperty("jdbcUrl"));
        comboPooledDataSource.setPassword(properties.getProperty("password"));
        comboPooledDataSource.setUser(properties.getProperty("username"));

        configuration.setDataSource(comboPooledDataSource);


        //mapper.xml 的解析 獲取到路徑 字節輸入流  dom4j 進行解析
        List<Element> mapperList = rootElement.selectNodes("//mapper");

        for (Element element : mapperList) {
            String resource = element.attributeValue("resource");
            InputStream resourceAsStream = Resource.getResourceAsStream(resource);
            XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(configuration);
            xmlMapperBuilder.parse(resourceAsStream);
        }

        return configuration;

    }
}

XMLMapperBuilder 解析Mapper.xml映射文件

package com.lwl.config;

import com.lwl.pojo.Configuration;
import com.lwl.pojo.MappedStatement;
import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

import java.io.InputStream;
import java.util.List;

/**
 * 解析Mapper.xml映射文件
 */
public class XMLMapperBuilder {

    private Configuration configuration;

    public XMLMapperBuilder(Configuration configuration) {
        this.configuration = configuration;
    }

    /**
     * 解析映射文件 的parse  對解析的值 進行封裝
     * @param in
     * @throws DocumentException
     */
    public void parse(InputStream in) throws DocumentException {
        //獲取文檔對象
        Document document = new SAXReader().read(in);

        //獲取根對象  mapper
        Element rootElement = document.getRootElement();
        //獲取namespace的值
        String namespace = rootElement.attributeValue("namespace");
        //集合中的element   是mapper映射文件中的  標籤
        List<Element> list = rootElement.selectNodes("//select");
        //獲取映射文件的每一個標籤值  並封裝到 MapperStatement
        for (Element element : list) {
            //statementId
            String id = element.attributeValue("id");
            //返回值類型
            String resultType = element.attributeValue("resultType");
            //參數類型
            String paramterType = element.attributeValue("paramterType");
            String sqlText = element.getTextTrim();

            MappedStatement mappedStatement = new MappedStatement();
            mappedStatement.setId(id);
            mappedStatement.setResultType(resultType);
            mappedStatement.setParameterType(paramterType);
            mappedStatement.setSql(sqlText);

            String key = namespace + "." + id;
            configuration.getMappedStatementMap().put(key,mappedStatement);

        }

    }
}

讀取數據庫配置信息及解析數據庫配置信息的編碼工作。