代码生成器-根据数据库生成对应Entity和Mapper

和真正mybatis generator的基于xml不同，笔者是建立在数据库已建好的基础上，分别进行Entity与Mapper的自动生成。

Entity包含所有的字段声明（private String username等）以及所有的get，set方法。
Mapper仅包含@Mapper下的接口的声明，以及一个insert方法。其他select以及update可以根据业务需要自行修改少部分代码进行生成，有任何疑问可以楼下评论，笔者会尽快回复。

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1. Entity

代码分为三个部分：

• 主功能类EntityGenerator
• 入口Generate
• 工具类SqlHelper

注释已经写的很清楚了，这里直接上代码：

1. EntityGenerator

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;

public class EntityGenerator {
    // 数据库连接
    private String URL;
    private String DBName;
    private String NAME;
    private String PASS;

    private String authorName = "undestiny";// 作者名字
    private String[] colnames; // 列名数组
    private String[] colTypes; // 列名类型数组
    private int[] colSizes; // 列名大小数组
    private boolean f_util = false; // 是否需要导入包java.util.*
    private boolean f_sql = false; // 是否需要导入包java.sql.*

    private SqlHelper sqlHelper = null;

    /*
     * 构造函数
     */
    public EntityGenerator(String url, String dbname, String username, String password) {
        this.URL = url + "/" + dbname;
        this.DBName = dbname;
        this.NAME = username;
        this.PASS = password;

        sqlHelper = new SqlHelper(this.URL, this.NAME, this.PASS);
    }

    public void Generate() {
        List<String> tableNames = sqlHelper.Get(
                "SELECT * FROM INFORMATION_SCHEMA.TABLES where TABLE_SCHEMA='" + DBName + "';", "TABLE_NAME");
        Connection con = null;
        try {
            con = sqlHelper.getConnection();
        } catch (ClassNotFoundException | SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        for (String table : tableNames) {
            Generate(table, con);
            System.out.println("generated: "+table );
            resetTableInfo();
        }
        try {
            sqlHelper.closeConnection(con);
        } catch (ClassNotFoundException | SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    private void resetTableInfo(){
        colnames = null;
        colTypes=null;
        colSizes=null;
        f_util=false;
        f_sql=false;
    }

    private String getPackageOutPath() {
        return "com.entity." + DBName;
    }

    private void Generate(String tablename, Connection con) {
        if (con == null) {
            System.out.println("------------------Connection to database was not set up------------------");
            return;
        }
        // 查要生成实体类的表
        String sql = "SELECT * FROM " + tablename + " limit 0, 1;";
        PreparedStatement pStemt = null;
        try {
            pStemt = con.prepareStatement(sql);
            ResultSetMetaData rsmd = pStemt.getMetaData();
            int size = rsmd.getColumnCount(); // 统计列
            colnames = new String[size];
            colTypes = new String[size];
            colSizes = new int[size];
            for (int i = 0; i < size; i++) {
                colnames[i] = rsmd.getColumnName(i + 1).replace(" ", "");
                colTypes[i] = rsmd.getColumnTypeName(i + 1);

                if (colTypes[i].equalsIgnoreCase("datetime") || colTypes[i].equalsIgnoreCase("date")) {
                    f_util = true;
                }
                if (colTypes[i].equalsIgnoreCase("image") || colTypes[i].equalsIgnoreCase("text")
                        || colTypes[i].equalsIgnoreCase("TIMESTAMP")) {
                    f_sql = true;
                }
                colSizes[i] = rsmd.getColumnDisplaySize(i + 1);
            }

            String content = parse(colnames, colTypes, colSizes, tablename);

            try {
                File directory = new File("");
                File dir = new File(directory.getAbsolutePath() + "/src/" + this.getPackageOutPath().replace(".", "/"