Java 数据库表生成 Entity 工具类

这是一个整理出来的JAVA工具类，用于将MySQL数据库表生成Entity实体类

package com.nmore.smile.utils;

import java.io.File;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

/**
 * @ClassName: GenEntity 
 * @Description: 数据库表生成Entity工具类
 * @Author devfzm@gmail.com
 * @Date 2016年2月29日 上午10:13:36 
 *
 */
public class GenEntity {

    //输出到自定义目录，为空代表输出到当前目录
    private static final String PATH = "";
    //包名(当指定PATH时，请同步修改PACKAGE，为空则默认为当前目录),如:com.nmore.smile.entity
    private static String PACKAGE = "";
true
    //数据库连接
    private static final String DATABASE = "imall";
    private static final String URL ="jdbc:mysql://localhost:3306/"+ DATABASE +"?useUnicode=true&characterEncoding=UTF8&useSSL=false";
    private static final String NAME = "root";
    private static final String PASS = "123456";
    private static final String DRIVER ="com.mysql.jdbc.Driver";
    
    //用于生成实体
    private String[] colnames; 				//列名数组
    private String[] colTypes; 				//列名类型数组
    private boolean f_util = false;			//是否需要导入包java.util.*
    //用于查询表的列详情，并读取生成注释
    private Statement stm;
    private ResultSet rs;
    
    //数据库连接
    private Connection con;

    /**
     * 构造函数
     */
    public GenEntity(){
    	//创建数据库连接
    	con = connectionDB();
    	try {
            /**
             * 以下提供两种生成方法，使用其中一种请注释另一种
             */
            //①此处可以自定定义需要生成的实体类表名，数组形式
            String[] arr = new String[]{"attr_name", "attr_value"};
            for(String str : arr){
                //开始生成实体类
                this.init(str, null);
            }
        	
            //②initAll,将数据库中所有表都生成[***Entity.java]
            //this.initAll();
        	
    	} catch (Exception e){
            e.printStackTrace();
    	} finally {
            try {
                //关闭数据库连接
                con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
    	}
    }
    
    /**
     * @Title: main 
     * @param args    
     * @return void
     */
    public static void main(String[] args) {
        System.out.println("Init..");
    	new GenEntity();
    	System.out.println("Init Complete..");
    }


    /**
     * @param tablename 表名
     * @param notes 注释,该参数为缺省字段，null就会去查询
     * @return 
     */
    @SuppressWarnings("unused")
    public void init(String tablename, String notes){
    	try {
            //查询要生成实体类的表
            String sql = "show full columns from `" + tablename + "`";
        	
            //执行查询，并获取结果
            stm = con.createStatement();
            rs = stm.executeQuery(sql);
            //统计行数,一行就是一个字段
        	
            rs.last();//移到最后一行
            int size = rs.getRow();   
            rs.beforeFirst();//如果还要用结果集，就把指针再移到初始化的位置  
        	
            colnames = new String[size];
            colTypes = new String[size];
            //读取查询的结果集
            int i = 0;
            while(rs.next()){
                //将列名和对应数据类型存入数组
                colnames[i] = rs.getString("Field");
                colTypes[i] = rs.getString("Type").replaceAll("[(].*[)]", "");
                //判断数据类型是否需要引入Util
                if(colTypes[i].equalsIgnoreCase("datetime")) f_util = true;
                
                i++;
            }
            //判断是否传递了注释,没有就去查询
            if(notes == null){
                notes = this.queryTableNotes(tablename).toString();
            }
            //拼装实体类内容
            String content = parse(colnames, colTypes, tablename, notes);
            try {
                File directory = new File("");
                String path = this.getClass().getResource("").getPath();
                //设置文件输出路径
                if(PATH == ""){
                    path = directory.getAbsolutePath() + "\\src\\main\\java\\" + path.substring(path.lastIndexOf("com/", path.length()), path.length()).replace("/", "\\");
                }else{
                    path = PATH;
                }
                //文件写入
                FileWriter fw = new FileWriter(path + initcap(tablename) + "Entity.java");
                PrintWriter pw = new PrintWriter(fw);
                pw.println(content);
                pw.flush();
                pw.close();
            } catch (Exception ex){
                ex.printStackTrace();
            }
        } catch (Exception e){
            e.printStackTrace();
        }
    }

    /**
     * @Title: initAll 
     * @Description: 初始化生成所有数据库表对应的Entity
     * @return void
     * @throws
     */
    @SuppressWarnings("unchecked")
    public void initAll(){
        //查询所有表表名和注释
        Map<String, String> table_notes = (Map<String, String>) queryTableNotes(null);
        //非空校验
    	if(table_notes != null){
            for (Map.Entry<String, String> entry : table_notes.entrySet()) { 
                //开始生成实体类
                this.init(entry.getKey(), entry.getValue());
            }
    	}
    }
true
    /**
     * 功能：生成实体类主体代码
     * @param colnames
     * @param colTypes
     * @param colSizes 
     * @param tablename 表名
     * @return 实体类主体代码字符串
     * @throws SQLException 
     */
    private String parse(String[] colnames, String[] colTypes, String tablename, String notes) throws SQLException {
        String entity = initcap(tablename);
    	StringBuffer sb = new StringBuffer();

        String path = this.getClass().getResource("").getPath();
        //获取包名
        PACKAGE = PACKAGE != ""?PACKAGE:path.substring(path.lastIndexOf("com/", path.length()), path.length()-1).replace("/", ".");
        //写入包名和依赖类
        sb.append("package "+ PACKAGE +";\r\n\r\n");
        sb.append("import com.nmore.smile.base.BaseEntity;\r\n");
        //判断是否导入工具包
        if(f_util){
            sb.append("import java.util.Date;\r\n");
            f_util = false;
        }
        
        sb.append("\r\n");
        //注释部分
        sb.append("/**\r\n");
        sb.append("* @ClassName: "+ entity +" \r\n");
        sb.append("* @Description: "+ notes +" \r\n");
        sb.append("* @Author devfzm@gmail.com \r\n");
        sb.append("* @Date "+ new Date() +" \r\n");
        sb.append("*/\r\n");
        //实体部分
        sb.append("\r\n@SuppressWarnings(\"serial\")\r\npublic class " + initcap(tablename) + "Entity extends BaseEntity {\r\n");
        processAllAttrs(sb);//属性
        processAllMethod(sb);//get set方法
        sb.append("}\r\n");
        
        return sb.toString();
    }
    /**
     * 功能：生成所有属性和对应注释
     * @param sb
     * @throws SQLException 
     */
    private void processAllAttrs(StringBuffer sb) throws SQLException {
    	int i = 0;
    	rs.beforeFirst();//如果还要用结果集，就把指针再移到初始化的位置
        while(rs.next()) {
            sb.append("\t//" + rs.getString("Comment"));
            sb.append("\n\tprivate " + sqlType2JavaType(colTypes[i]) + " " + colnames[i] + ";\r\n");
            i++;
        }
        sb.append("\r\n");
        rs.close();
        stm.close();
    }
 
    /**
     * 功能：生成所有 Getter/Setter 方法
     * @param sb
     */
    private void processAllMethod(StringBuffer sb) {
        for (int i = 0; i < colnames.length; i++) {
            sb.append("\tpublic void set" + initcap(colnames[i]) + "(" + sqlType2JavaType(colTypes[i]) + " " + 
                    colnames[i] + "){\r\n");
            sb.append("\t\tthis." + colnames[i] + "=" + colnames[i] + ";\r\n");
            sb.append("\t}\r\n");
            sb.append("\tpublic " + sqlType2JavaType(colTypes[i]) + " get" + initcap(colnames[i]) + "(){\r\n");
            sb.append("\t\treturn " + colnames[i] + ";\r\n");
            sb.append("\t}\r\n");
        }
         
    }

    /**
     * 功能：获得列的数据类型
     * @param sqlType
     * @return javaType
     */
    private String sqlType2JavaType(String sqlType) {
        if(sqlType.equalsIgnoreCase("bit")){
            return "Boolean";
        }else if(sqlType.equalsIgnoreCase("tinyint")){
            return "byte";
        }else if(sqlType.equalsIgnoreCase("smallint")){
            return "short";
        }else if(sqlType.equalsIgnoreCase("int")){
            return "Integer";
        }else if(sqlType.equalsIgnoreCase("bigint")){
            return "long";
        }else if(sqlType.equalsIgnoreCase("float")){
            return "float";
        }else if(sqlType.equalsIgnoreCase("decimal") || sqlType.equalsIgnoreCase("numeric") 
                || sqlType.equalsIgnoreCase("real") || sqlType.equalsIgnoreCase("money") 
                || sqlType.equalsIgnoreCase("smallmoney")){
            return "Double";
        }else if(sqlType.equalsIgnoreCase("varchar") || sqlType.equalsIgnoreCase("char") 
                || sqlType.equalsIgnoreCase("nvarchar") || sqlType.equalsIgnoreCase("nchar") 
                || sqlType.equalsIgnoreCase("text")){
            return "String";
        }else if(sqlType.equalsIgnoreCase("datetime")){
            return "Date";
        }else if(sqlType.equalsIgnoreCase("image")){
            return "Blod";
        }
        return null;
    }
    
    /**
     * 功能：将输入字符串的首字母和"_a"格式的字母改成大写
     * @param str
     * @return
     */
    private String initcap(String str) {
        char[] ch = str.toCharArray();
    	if(ch[0] >= 'a' && ch[0] <= 'z'){
            ch[0] = (char)(ch[0] - 32);
        }
        return new String(ch);
    }
    
    /**
     * @Title: queryTableNotes 
     * @Description: 查询表注释
     * @param tableName 该参数为缺省参数，不传默认查询所有表
     * @return Object
     * @throws
     */
    public Object queryTableNotes(String tableName){
    	try {
            //查询表名称和注释,默认查询数据库的全部表（即tableName为null时）
            String sql = "select table_name,table_comment from information_schema.`TABLES` WHERE table_schema = '"+ DATABASE +"'";
            if(tableName != null){
                sql += " and table_name='"+ tableName +"'";
            }
            //执行查询，并获取结果
            Statement sta = con.createStatement();
            ResultSet rst = sta.executeQuery(sql);
            //读取查询结果
            if(tableName != null){
                String str = ""; 
            	while(rst.next()){
                    str = rst.getString("table_comment");
            	}
                sta.close();
                rst.close();
                return str;
            }else{
                Map<String, String> map = new HashMap<String, String>();
            	while(rst.next()){
                    map.put(rst.getString("table_name"), rst.getString("table_comment"));
            	}
            	sta.close();
                rst.close();
            	return map;
            }
    	} catch (Exception e){
            e.printStackTrace();
            return null;
    	}
    }
    
    /**
     * 建立数据的连接
     * @exception SQLException, ClassNotFoundException
     */
    public Connection connectionDB(){
        try{
            Class.forName(DRIVER);
            Connection conn = DriverManager.getConnection(URL, NAME, PASS);
            //System.out.println("连接数据库成功");
            return conn;
        }catch(Exception e){
            e.printStackTrace();
            //System.out.println("建立数据库发生错误！");
            return null;
        }
    }
 
}