Mybatis三剑客自动生成带数据库注释的实体类及Mapper,接口

SSM项目中，一旦数据库表多且列也多的时候，一个一个根据数据库手敲代码是及其不明智的选择，Mybatis虽然不像Hibernate那样全自动化的生成，但也提供了相关联的插件，今天我们按照一步一步的操作去进行生成相关联的数据文件.
介绍一个反编译工具——jd-gui

下载地址:http://jd.benow.ca/
首先我们需要先下载反编译工具,这里暂时不用，后面会用得到.
1.打开IDEA Settings-Plugins-Browse repositores-搜索Mybatis Plugin插件进行安装
2.安装之后创建Maven项目，此处不再多说，在pom.xml文件当中引入依赖

            org.mybatis.generator
            mybatis-generator-core
            1.3.2
        
         
            log4j
            log4j
            1.2.7
        
        
            org.apache.ant
            ant
            1.9.0
 
 
            mysql
            mysql-connector-java
            5.1.25
        

这个依赖就是Generator的依赖文件，如果不引入log4j文件就报错:

log4j:WARN No appenders could be found for logger (org.mybatis.generator.internal.db.DatabaseIntrospector).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

如果引入了还报错但是实体类等配置文件已出现那么就不要强求这个错误了，往下走
这个时候在模块的resource资源配置文件中创建generatorConfig.xml，配置文件当中的配置如下:

当我们配置好这个Generator的配置文件之后，因为我们是在IDEA中创建Maven项目的，习惯性的使用右边栏的Maven菜单进行操作，所以我们需要配置一个操作按钮,在pom.xml中代码如下:

        
            
            
                
                org.mybatis.generator
                mybatis-generator-maven-plugin
                1.3.2
                
                    
                    src/main/resources/generatorConfig.xml
                    true
                    true
                
                
                    
                        Generate MyBatis Artifacts
                        
                            generate
                        
                    
                
                
                    
                        org.mybatis.generator
                        mybatis-generator-core
                        1.3.2
                    
                
            
        
    

这个代码输入后查看侧边栏，出现按钮:

如果说，这个时候单击按钮那么他是能映射出来相关联文件的，但是我们是要做在实体类当中生成的注释是数据表中列的注释，以供更多人开发项目是方便查看.
这个时候我们对第一步进行下载操作，找到适合自己电脑系统的版本进行下载，随便解压到某个目录，然后打开，如下：

双击进入之后找到File-----Open File打开，我是到我的Maven仓库当中找到jar包进行反编译出来，如图：
找到需要更改的类，Ctrl+S保存到IDEA的java代码目录中，因为我们需要将编译后的.class文件进行替换原文件,如图:

保存到目录之后,将这个类进行更改，这个时候是关键的步骤，这个类才是实体类生成数据库中文注释的关键,如下:

/*
 *  Copyright 2008 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.mybatis.generator.internal;

import static org.mybatis.generator.internal.util.StringUtility.isTrue;

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

import org.mybatis.generator.api.CommentGenerator;
import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.IntrospectedTable;
import org.mybatis.generator.api.dom.java.CompilationUnit;
import org.mybatis.generator.api.dom.java.Field;
import org.mybatis.generator.api.dom.java.InnerClass;
import org.mybatis.generator.api.dom.java.InnerEnum;
import org.mybatis.generator.api.dom.java.JavaElement;
import org.mybatis.generator.api.dom.java.Method;
import org.mybatis.generator.api.dom.java.Parameter;
import org.mybatis.generator.api.dom.xml.TextElement;
import org.mybatis.generator.api.dom.xml.XmlElement;
import org.mybatis.generator.config.MergeConstants;
import org.mybatis.generator.config.PropertyRegistry;

/**
 * @author Jeff Butler
 * 
 */
public class DefaultCommentGenerator implements CommentGenerator {
    private Properties properties;
    private Properties systemPro;
    private boolean suppressDate;
    private boolean suppressAllComments;
    private String currentDateStr;

    public DefaultCommentGenerator() {
        super();
        properties = new Properties();
        systemPro = System.getProperties();
        suppressDate = false;
        suppressAllComments = false;
        currentDateStr = (new SimpleDateFormat("yyyy-MM-dd")).format(new Date());
    }

    public void addJavaFileComment(CompilationUnit compilationUnit) {
        // add no file level comments by default
        return;
    }

    /**
     * Adds a suitable comment to warn users that the element was generated, and
     * when it was generated.
     */
    public void addComment(XmlElement xmlElement) {
        return;
    }

    public void addRootComment(XmlElement rootElement) {
        // add no document level comments by default
        return;
    }

    public void addConfigurationProperties(Properties properties) {
        this.properties.putAll(properties);

        suppressDate = isTrue(properties.getProperty(PropertyRegistry.COMMENT_GENERATOR_SUPPRESS_DATE));

        suppressAllComments = isTrue(properties.getProperty(PropertyRegistry.COMMENT_GENERATOR_SUPPRESS_ALL_COMMENTS));
    }

    /**
     * This method adds the custom javadoc tag for. You may do nothing if you do
     * not wish to include the Javadoc tag - however, if you do not include the
     * Javadoc tag then the Java merge capability of the eclipse plugin will
     * break.
     *
     * @param javaElement
     *            the java element
     */
    protected void addJavadocTag(JavaElement javaElement, boolean markAsDoNotDelete) {
        javaElement.addJavaDocLine(" *");
        StringBuilder sb = new StringBuilder();
        sb.append(" * ");
        sb.append(MergeConstants.NEW_ELEMENT_TAG);
        if (markAsDoNotDelete) {
            sb.append(" do_not_delete_during_merge");
        }
        String s = getDateString();
        if (s != null) {
            sb.append(' ');
            sb.append(s);
        }
        javaElement.addJavaDocLine(sb.toString());
    }

    /**
     * This method returns a formated date string to include in the Javadoc tag
     * and XML comments. You may return null if you do not want the date in
     * these documentation elements.
     *
     * @return a string representing the current timestamp, or null
     */
    protected String getDateString() {
        String result = null;
        if (!suppressDate) {
            result = currentDateStr;
        }
        return result;
    }

    public void addClassComment(InnerClass innerClass, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        innerClass.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedTable.getFullyQualifiedTable());
        sb.append(" ");
        sb.append(getDateString());
        innerClass.addJavaDocLine(sb.toString().replace("\n", " "));
        innerClass.addJavaDocLine(" */");
    }

    public void addEnumComment(InnerEnum innerEnum, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        innerEnum.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedTable.getFullyQualifiedTable());
        innerEnum.addJavaDocLine(sb.toString().replace("\n", " "));
        innerEnum.addJavaDocLine(" */");
    }

    public void addFieldComment(Field field, IntrospectedTable introspectedTable,
                                IntrospectedColumn introspectedColumn) {
        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        field.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedColumn.getRemarks());
        field.addJavaDocLine(sb.toString().replace("\n", " "));
        field.addJavaDocLine(" */");
    }

    public void addFieldComment(Field field, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        field.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedTable.getFullyQualifiedTable());
        field.addJavaDocLine(sb.toString().replace("\n", " "));
        field.addJavaDocLine(" */");
    }

    public void addGeneralMethodComment(Method method, IntrospectedTable introspectedTable) {
        if (suppressAllComments) {
            return;
        }
        //      method.addJavaDocLine("/**");
        //      addJavadocTag(method, false);
        //      method.addJavaDocLine(" */");
    }

    public void addGetterComment(Method method, IntrospectedTable introspectedTable,
                                 IntrospectedColumn introspectedColumn) {
        if (suppressAllComments) {
            return;
        }
        method.addJavaDocLine("/**");
        StringBuilder sb = new StringBuilder();
        sb.append(" * ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString().replace("\n", " "));
        sb.setLength(0);
        sb.append(" * @return ");
        sb.append(introspectedColumn.getActualColumnName());
        sb.append(" ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString().replace("\n", " "));
        method.addJavaDocLine(" */");
    }

    public void addSetterComment(Method method, IntrospectedTable introspectedTable,
                                 IntrospectedColumn introspectedColumn) {
        if (suppressAllComments) {
            return;
        }
        method.addJavaDocLine("/**");
        StringBuilder sb = new StringBuilder();
        sb.append(" * ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString().replace("\n", " "));
        Parameter parm = method.getParameters().get(0);
        sb.setLength(0);
        sb.append(" * @param ");
        sb.append(parm.getName());
        sb.append(" ");
        sb.append(introspectedColumn.getRemarks());
        method.addJavaDocLine(sb.toString().replace("\n", " "));
        method.addJavaDocLine(" */");
    }

    public void addClassComment(InnerClass innerClass, IntrospectedTable introspectedTable, boolean markAsDoNotDelete) {
        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        innerClass.addJavaDocLine("/**");
        sb.append(" * 描述:");
        sb.append(introspectedTable.getFullyQualifiedTable()+"表的实体类");
        innerClass.addJavaDocLine(sb.toString().replace("\n", " "));
        sb.setLength(0);
        sb.append(" * @version");
        innerClass.addJavaDocLine(sb.toString().replace("\n", " "));
        sb.setLength(0);
        sb.append(" * @author:  ");
        sb.append(systemPro.getProperty("user.name"));
        innerClass.addJavaDocLine(sb.toString().replace("\n", " "));
        sb.setLength(0);
        sb.append(" * @创建时间: ");
        sb.append(currentDateStr);
        innerClass.addJavaDocLine(sb.toString().replace("\n", " "));
        innerClass.addJavaDocLine(" */");
    }
}

更改完毕之后,直接找到侧边栏Maven的操作列表进行package打包，将打包后的target目录下的这个编译后的.class文件复制出来，找到仓库地址，通过压缩软件进行解压到当前目录下，如:

然后找到之前更改的文件地址，将这个文件进行删除，因为他不可编写，删除后，将IDEA打包后的文件进行复制粘贴丢进去，然后在将这个文件打包成.jar类型的替换原来的jar，最后进行生成，实体类成功带上数据库注释，如下: