java实体类的自动生成

在工作中有时候需要用到建立实体类，从数据库中读取各个表格自动的生成实体类，如果表的数量比较大的时候，这个繁琐的工作量还是比较大的，这时候可以用一个小程序自动的生成实体类。其实，就是文件的读写操作而已。

数据库这里用的是mysql5.1，所以需要导入maysql的jar包。

config.properties

url=jdbc:mysql://localhost:3306/ibatis
driver=com.mysql.jdbc.Driver
username=root
password=root

 

DBUtils.java

package utils;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;


public class DBUtils {
	private static Properties prop = new Properties();
	static{
		ClassLoader loader = DBUtils.class.getClassLoader();
		InputStream in = loader.getResourceAsStream("utils/config.properties");
		try {
			prop.load(in);
			Class.forName(prop.getProperty("driver"));
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	public static Connection getConnection() throws Exception{
		return DriverManager.getConnection(prop.getProperty("url"),prop.getProperty("username"),prop.getProperty("password"));
	}
	
	public static void close(Connection conn){
		if(conn != null){
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
	
	public static void main(String[] args) throws Exception{
		System.out.println(getConnection());
	}
}

 

GenEntityTool.java

package biz;

import java.io.FileWriter;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;

import utils.DBUtils;

public class GenEntityTool {
	private String[] colNames;//列名数组
	private String[] colType;//列名类型数组
	private int[] colSize;//列名大小数组
	private boolean f_util = false;//是否需要导入java.util.*
	private boolean f_sql = false;//是否需要导入java.sql.*
	
	public GenEntityTool(){}
	public GenEntityTool(String tabName){
		
		Connection conn = null;
		String sql = "select * from " + tabName;
		try {
			conn = DBUtils.getConnection();
			PreparedStatement prep = conn.prepareStatement(sql);
			ResultSetMetaData rsmd = prep.getMetaData();
			int size = rsmd.getColumnCount();//共有多少列
			colNames = new String[size];
			colType = new String[size];
			colSize = new int[size];
			for(int i=0;i<rsmd.getColumnCount();i++){
				colNames[i] = rsmd.getColumnName(i+1);
				colType[i] = rsmd.getColumnTypeName(i+1);
				if(colType[i].equalsIgnoreCase("date")){
					f_util = true;
				}
				if(colType[i].equalsIgnoreCase("text") || colType[i].equalsIgnoreCase("image")){
					f_sql = true;
				}
				colSize[i] = rsmd.getColumnDisplaySize(i+1);
			}
			String content = parse(tabName, colNames, colType, colSize);
			FileWriter fw = new FileWriter("E:\\entity\\"+initCap(tabName)+".java");
			PrintWriter pw = new PrintWriter(fw);
			pw.println(content);
			pw.flush();
			pw.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			DBUtils.close(conn);
		}
	}
	
	/*
	 * 解析处理，生成java实体类主体代码
	 */
	private String parse(String tabName,String[] colNames,String[] colType,int[] colSize){
		StringBuffer sb = new StringBuffer();
		if(f_util){
			sb.append("import java.util.Date;\r\n");
		}
		if(f_sql){
			sb.append("import java.sql.*;\r\n\r\n\r\n");
		}
		sb.append("public class "+initCap(tabName)+"{\r\n");
		processAllAttrs(sb);
		processAllMethod(sb);
		sb.append("}\r\n");
		return sb.toString();
	}
	
	/*
	 * 生成所有的方法
	 */
	private void processAllMethod(StringBuffer sb){
		for(int i=0;i<colNames.length;i++){
			sb.append("\tpublic void set"+initCap(colNames[i])+"("+sqlType2JavaType(colType[i])+" "+colNames[i]+"){\r\n");
			sb.append("\t\tthis."+colNames[i]+" = "+colNames[i]+";\r\n");
			sb.append("\t}\r\n");
			
			sb.append("\tpublic "+sqlType2JavaType(colType[i])+" get"+initCap(colNames[i])+"(){\r\n");
			sb.append("\t\treturn "+colNames[i]+";\r\n");
			sb.append("\t}\r\n");
		}
	}
	
	/*
	 * 解析输出属性
	 * 
	 * @return
	 */
	private void processAllAttrs(StringBuffer sb){
		for(int i=0;i<colNames.length;i++){
			sb.append("\tprivate "+sqlType2JavaType(colType[i])+" "+colNames[i]+";\r\n");
		}
	}
	
	/*
	 * 把输入字符串的首字母变成大写
	 * 
	 * @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);
	}
	
	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 "int";
		} else if (sqlType.equalsIgnoreCase("bigint")) {
			return "long";
		} else if (sqlType.equalsIgnoreCase("float")) {
			return "float";
		} else if (sqlType.equalsIgnoreCase("decimal")
				|| sqlType.equalsIgnoreCase("numeric")
				|| sqlType.equalsIgnoreCase("double")
				|| sqlType.equalsIgnoreCase("real")) {
			return "double";
		} else if (sqlType.equalsIgnoreCase("money")
				|| sqlType.equalsIgnoreCase("smallmoney")) {
			return "double";
		} else if (sqlType.equalsIgnoreCase("varchar")
				|| sqlType.equalsIgnoreCase("char")
				|| sqlType.equalsIgnoreCase("nvarchar")
				|| sqlType.equalsIgnoreCase("nchar")) {
			return "String";
		} else if (sqlType.equalsIgnoreCase("datetime")
				|| sqlType.equalsIgnoreCase("date")) {
			return "Date";
		}

		else if (sqlType.equalsIgnoreCase("image")) {
			return "Blob";
		} else if (sqlType.equalsIgnoreCase("text")) {
			return "Clob";
		}
		return null;
	}  
	
	/*
	 * 读取数据库中的表名
	 * @return表名的String数组
	 * 
	 */
	private static String[] getTabNames(){
		Connection conn = null;
		String sql = "show tables";
		String[] tabNames = null;
		
		try {
			conn = DBUtils.getConnection();
			PreparedStatement  prep = conn.prepareStatement(sql);
			ResultSet rs = prep.executeQuery();
			rs.last();
			int size = rs.getRow();
			tabNames = new String[size];
			rs.beforeFirst();
			int i=0;
			while(rs.next() && i < size){
				tabNames[i]=rs.getString(1);
				i++;
			}
			
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			DBUtils.close(conn);
		}
		return tabNames;
	}
	
	
	public static void main(String[] args){
		String[] tabNames = getTabNames();
		for(int i=0;i<tabNames.length;i++){
			new GenEntityTool(tabNames[i]);
		}
	}
}

 

主题代码已经贴上去了，下面来进行一次啊测试...

Test.java

package biz;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import utils.DBUtils;

public class Test {
	
	
	
	
	public static void main(String[] args){
		String sql = "show tables";
		Connection conn = null;
		try {
			conn = DBUtils.getConnection();
			PreparedStatement prep = conn.prepareStatement(sql);
			ResultSet rs = prep.executeQuery();
			while(rs.next()){
				System.out.println(rs.getString(1));
			}
			
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			DBUtils.close(conn);
		}
	}
}