生成实体类

生成实体类

开发工具与关键技术：MyEclipse 10、java
作者：梁添荣
撰写时间：2019-6-08

做项目是不免需要创建实体类与数据库表联系，但如果每一张表一张表去创建的话，不免浪费时间，所有做一个util实现生成实体类
思路如下：
1.	明白实体类结构
2.	创建连接，获取表名，进而获取其列的属性
3.	按照实体类的结构的，写出实体类文件
package com.gx.ts;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
public class CreateEntityUtil {
	private final String DRIVER="com.mysql.jdbc.Driver";
	private final String URL="jdbc:mysql://localhost:3306/demo?serverTimezone=GMT%2B8";
	private final String USER="root";
	private final String PASSWORD="root";	
	String packageName="com/gx/po";//包名
	Connection con;
	DatabaseMetaData md;
	ResultSet rs;
	ResultSetMetaData rsm;
	PreparedStatement ps;
//获取所有表名
	public void TableList(){	
		try {
			Class.forName(DRIVER);
			con=DriverManager.getConnection(URL,USER,PASSWORD);
			md=con.getMetaData();//获取数据库的元数据	
			rs=md.getTables(con.getCatalog(), null, "%", null);//获取可在给定类别中使用的表的描述
			while(rs.next()){		
				String tableName=rs.getString("TABLE_NAME");//获取表名			
				ColProperties(tableName);
			}
		} catch (ClassNotFoundException e) {		
			e.printStackTrace();
		}catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			try {
				rs.close();
				md=null;
				con.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
//获取表里的列的属性
	public void ColProperties(String tableName){
		try {
			Class.forName(DRIVER);
			con=DriverManager.getConnection(URL,USER,PASSWORD);
			ps=con.prepareStatement("select * from "+tableName);
			rsm=ps.getMetaData();//表的结构
			int size=rsm.getColumnCount();//多少列
			//设置列名、列名类型、列名大小数组长度
			String[] colNames=new String[size];
			String[] colTypes=new String[size];
			int[] colSizes=new int[size];
			//获取列的属性
			for (int i = 0; i < size; i++) {
				colNames[i]=rsm.getColumnName(i+1);//列名
				colTypes[i]=LowerColTypes(rsm.getColumnTypeName(i+1));//列类型，获取到的是大写所以转小写。
//ps：若知道各个类型需要的jra包，可以把jra包也输入文件
				//记录是否引入jra包
//				if(colTypes[i].equals("image")||colTypes[i].equals("text")){
//					f_sql=true;
//				}else{
//					f_sql=false;
//				}
//				if(colTypes[i].equals("datetime")){
//					f_util=true;
//				}else{
//					f_util=false;
//				}
				colSizes[i]=rsm.getColumnDisplaySize(i+1);
			}
			//传递表名、列名数组、列类型数组、列大小数组
			CreateEntiy(Inincap(tableName),colNames,colTypes,colSizes);
		} catch (ClassNotFoundException e) {	
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			try {
				rsm=null;
				ps.close();
				con.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}	
	}
//创建实体类,保存到文件夹
	public void CreateEntiy(String tableName,String[] colNames,String[] colTypes,int[] colSizes){
		String path=System.getProperty("user.dir")+"/src/"+packageName;
		File folder=new File(path);
		if(!folder.exists()){
			folder.mkdir();
		}
		FileWriter fw = null;
		try {
			String fileName=path+"/"+tableName+".java";
			File file=new File(fileName);
			fw=new FileWriter(file);
			StringBuffer sb=new StringBuffer();
		//开始添加内容
			//包名
			sb.append("package\t"+packageName.replace("/", ".")+";");///r/n??
//			if(f_util==true){
//				sb.append("import java.util.Date;\r\n");
//			}
//			if(f_sql==true){
//				sb.append("import java.sql.*;\r\n");
//			}
			sb.append("\r\nimport java.io.Serializable;\r\n");
			//class
			sb.append("public class "+tableName+" implements Serializable{\r\n");
			//添加变量
			for (int i = 0; i < colTypes.length; i++) {
				sb.append("\tprivate "+TypeCast(colTypes[i])+" "+colNames[i]+";\r\n");
			}
			//添加构造器
			sb.append("\tpublic "+tableName+"(){}\r\n\tpublic "+tableName+"(");
			for (int i = 0; i < colTypes.length; i++) {
				String colType=TypeCast(colTypes[i]);
				if(i<colTypes.length-1){
					sb.append(colType+" "+colNames[i]+", ");
				}else{
					sb.append(colType+" "+colNames[i]+"){\r\n\t");
				}
			}
			for (int i = 0; i < colTypes.length; i++) {
				sb.append("this."+colNames[i]+"="+colNames[i]+";\r\n\t");
			}
			sb.append("}\r\n");
			//添加get、set
			for (int i = 0; i < colTypes.length; i++) {		
				String colType=TypeCast(colTypes[i]);
				sb.append("\tpublic "+colType+" get"+Inincap(colNames[i])+"(){\r\n\treturn "+colNames[i]+";\r\n\t}\r\n");	
				sb.append("\tpublic void set"+Inincap(colNames[i])+"("+colType+" "+colNames[i]+"){\r\n\tthis."+colNames[i]+" ="+colNames[i]+";\r\n\t}\r\n");
			}
			sb.append("}");
			fw.write(sb.toString());
			fw.flush();	
		} catch (IOException e) {
			e.printStackTrace();
		}finally{
			try {
				fw.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
//列名转小写
	public String LowerColTypes(String colTypes){
		String colType=colTypes.toLowerCase();
		return colType;
	}
//列名首字母转小写
	public String Lowercase(String colNames){		
		String colNames2=colNames.substring(0,1).toLowerCase()+colNames.substring(1);
		return colNames2;
	}
//表名首字母转大写
	public String Inincap(String tableName){
		String tableName2=tableName.substring(0,1).toUpperCase()+tableName.substring(1);
		return tableName2;
	}
//转换列名类型
	public String TypeCast(String colTypes){
//ps：此处说明，switch参数是String类型的话必须是JavaSE-1.7
	如果此前没有，更改为JavaSE-1.7可能会使项目报错，可以用if语句代替
		switch(colTypes){
		case "bigint":return "long";
		case "binary":return "byte[]";
		case "bit": return "boolean";
		case "blob": return "byte[]";
		case "bool": return "bool";
		case "boolean": return "boolean";
		case "char": return "String";
		case "date": return "Date";
		case "datetime": return "Timestamp";
		case "decimal": return "double";
		case "double": return "double";
		case "enum": return "String";
		case "float": return "float";
		case "int": return "int";
		case "longblob": return "byte[]";
		case "longtext": return "String";
		case "mediumblob": return "byte[]";
		case "mediumint": return "";
		case "mediumtext": return "String";
		case "numeric": return "double";
		case "real":return "double";
		case "set":return "String";
		case "smallint":return "short";
		case "text":return "String";
		case "time":return "Date";
		case "tiemstamp":return "Date";
		case "tinyblob":return "byte[]";
		case "tinyint":return "byte[]";
		case "tinytext":return "String";
		case "varbinary":return "byte[]";
		case "varchar":return "String";
		case "year":return "Date";
		}
		return colTypes;
		
	}
	public static void main(String[] args) {
		CreateEntityUtil createEntityUtil=new CreateEntityUtil();
		createEntityUtil.TableList();
		System.out.print("创建完成！");
	}
}