把mysql数据库中的表通过java代码生成实体类

          本来，自己的项目是通过mybatis自动生成这些的，但是不一定其他项目使用，于是趁闲着就看看怎么通过代码写生成，看来很多都不是太满意。于是借鉴了一篇，然后修改了一下。生成了自己想要的实体类。

package com.db.gen.entity.tool;import java.io.File;import java.io.FileWriter;import java.io.IOException;import java.io.PrintWriter;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.sql.SQLException;import java.util.Date;import java.util.HashMap;import java.util.Map;public class GenEntityMysql {private String packageOutPath = "com.entity.biz_debt";//指定实体生成所在包的路径private String authorName = "orange";//作者名字private String tablename = "biz_debt";//表名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 Map comment; //字段注释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.*        //数据库连接private static final String URL ="jdbc:mysql://localhost:3306/cheguan";private static final String NAME = "root";private static final String PASS = "root";private static final String DRIVER ="com.mysql.jdbc.Driver";/* * 构造函数 */public GenEntityMysql(){    //创建连接    Connection con = null;//查要生成实体类的表    String sql = "select * from " + tablename;    PreparedStatement pStemt = null;    PreparedStatement pStemt2 = null;    try {    try {Class.forName(DRIVER);} catch (ClassNotFoundException e1) {e1.printStackTrace();}    con = DriverManager.getConnection(URL,NAME,PASS);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);colTypes[i] = rsmd.getColumnTypeName(i + 1);if(colTypes[i].equalsIgnoreCase("datetime")){f_util = true;}if(colTypes[i].equalsIgnoreCase("image") || colTypes[i].equalsIgnoreCase("text")){f_sql = true;}colSizes[i] = rsmd.getColumnDisplaySize(i + 1);}//获取数据库字段注释String commentSql = " show full fields from " + tablename; comment = new HashMap();    pStemt2 = con.prepareStatement(commentSql);    ResultSet rs2 = pStemt2.executeQuery();    while(rs2.next()){    String comm  = rs2.getString("Comment");    if(null != comm && !comm.equals("")){    comment.put(rs2.getString("Field"), comm);    }else{    comment.put(rs2.getString("Field"), rs2.getString("Field"));    }    }    System.out.println(comment);String content = parse(colnames,colTypes,colSizes);try {File directory = new File("");String outputPath = directory.getAbsolutePath()+ "\\src\\"+this.packageOutPath.replace(".", "\\") + "\\";File file = new File(outputPath);file.mkdirs();  FileWriter fw = new FileWriter(outputPath + initcap(colnameToHump(tablename)) + ".java");PrintWriter pw = new PrintWriter(fw);pw.println(content);pw.flush();pw.close();} catch (IOException e) {e.printStackTrace();}} catch (SQLException e) {e.printStackTrace();} finally{try {con.close();} catch (SQLException e) {e.printStackTrace();}}    }/** * 功能：生成实体类主体代码 * @param colnames * @param colTypes * @param colSizes * @return */private String parse(String[] colnames, String[] colTypes, int[] colSizes) {StringBuffer sb = new StringBuffer();sb.append("package " + this.packageOutPath + ";\r\n");sb.append("\r\n");//判断是否导入工具包if(f_util){sb.append("import java.util.Date;\r\n");}if(f_sql){sb.append("import java.sql.*;\r\n");}//注释部分sb.append("\r\n");sb.append("/**\r\n");sb.append(" * "+tablename+" 实体类\r\n");sb.append(" * "+new Date()+" "+this.authorName + "\r\n");sb.append(" */ \r\n");//实体部分sb.append("\r\n");sb.append("public class " + initcap(colnameToHump(tablename)) + " {\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 * @param sb */private void processAllAttrs(StringBuffer sb) {for (int i = 0; i < colnames.length; i++) {sb.append("\r\n");sb.append("   /**\r\n");sb.append("     * "+ comment.get(colnames[i]) + "\r\n");sb.append("     */ \r\n");sb.append("\tprivate " + sqlType2JavaType(colTypes[i]) + " " + colnameToHump(colnames[i]) + ";\r\n");}}/** * 功能：生成getter,setter方法 * @param sb */private void processAllMethod(StringBuffer sb) {for (int i = 0; i < colnames.length; i++) {sb.append("\tpublic " + sqlType2JavaType(colTypes[i]) + " get" + initcap(colnameToHump(colnames[i])) + "(){\r\n");sb.append("\t\treturn " + colnameToHump(colnames[i]) + ";\r\n");sb.append("\t}\r\n");sb.append("\r\n");sb.append("\tpublic void set" + initcap(colnameToHump(colnames[i])) + "(" + sqlType2JavaType(colTypes[i]) + " " + colnameToHump(colnames[i]) + "){\r\n");sb.append("\t\tthis." + colnameToHump(colnames[i]) + " = " + colnameToHump(colnames[i]) + ";\r\n");sb.append("\t}\r\n");sb.append("\r\n");}}/** * 功能：将数据库的字段改成驼峰命名的方式 */public String colnameToHump(String colnames) {String[] tf = colnames.split("_");String newColName = "";for(int i=0; i 0) {tf[i] = initcap(tf[i]);}newColName = newColName + tf[i];}return newColName;}/** * 功能：将输入字符串的首字母改成大写 * @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);}/** * 功能：获得列的数据类型 * @param sqlType * @return */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("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;}/** * 出口 * @param args */public static void main(String[] args) {new GenEntityMysql();}}

生成后需要F5刷新项目，才会出现。

转载：http://blog.csdn.net/goodleiwei/article/details/8439023