利用Java将Mysql数据表生成JPA实体对象

便民

package cn.lry.iteye.jpa.tool;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
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;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
/**
* 从数据库表反射出实体类，自动生成实体类
* @author lry
*
*/
public class GenEntityMysql {
private String packageOutPath = "cn.lry.iteye.jpa.po";//指定实体生成所在包的路径
private String authorName = "lry";//作者名字
private String tablename = "";//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 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 boolean f_jpa = true; // 是否需要生成基于注解的JPA实体对象
//数据库连接
private static final String URL ="jdbc:mysql://localhost:3306/yu120";
private static final String NAME = "root";
private static final String PASS = "123456";
private static final String DRIVER ="com.mysql.jdbc.Driver";
/*
* 构造函数
*/
public GenEntityMysql(){
List<String> list=getTableName();
for(int p=0;p<list.size();p++){
tablename=list.get(p);
//创建连接
Connection con;
//查要生成实体类的表
String sql = "select * from " + tablename;
PreparedStatement pStemt = 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 = rsmd.getColumnName(i + 1);
colTypes = rsmd.getColumnTypeName(i + 1);
if(colTypes.equalsIgnoreCase("datetime")){
f_util = true;
}
if(colTypes.equalsIgnoreCase("image") || colTypes.equalsIgnoreCase("text")){
f_sql = true;
}
colSizes = rsmd.getColumnDisplaySize(i + 1);
}
String content = parse(colnames,colTypes,colSizes);
try {
File directory = new File("");
String outputPath = directory.getAbsolutePath()+ "/src/"+this.packageOutPath.replace(".", "/")+"/"+initcap(tablename) + ".java";
FileWriter fw = new FileWriter(outputPath);
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) {
//// TODO Auto-generated catch block
//e.printStackTrace();
//}
}
}
System.out.println("生成完毕！");
}
/**
* Java方法 得到当前数据库下所有的表名
* @param con
*/
private List<String> getTableName() {
List<String> list=new ArrayList<String>();
try {  
DatabaseMetaData meta = DriverManager.getConnection(URL,NAME,PASS).getMetaData();  
ResultSet rs = meta.getTables(null, null, null,new String[]{"TABLE"});
while (rs.next()) {
list.add(rs.getString(3));  
}  
}catch(Exception e){  
e.printStackTrace();  
}
return list;
}
/**
* 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");
}
//jpa
if(f_jpa){
sb.append("import javax.persistence.Entity;\r\n");
sb.append("import javax.persistence.GeneratedValue;\r\n");
sb.append("import javax.persistence.GenerationType;\r\n");
sb.append("import javax.persistence.Id;\r\n\r\n");
}
//注释部分
sb.append("/**\r\n");
sb.append(" * "+tablename+" 实体类\r\n");
sb.append(" * "+new Date()+"\r\n");
sb.append(" * @"+this.authorName+"\r\n");
sb.append(" */ \r\n");
if(f_jpa){
sb.append("@Entity\r\n");
}
//实体部分
sb.append("public class " + initcap(tablename) + "{\r\n\r\n");
processAllAttrs(sb);//属性
processAllMethod(sb);//get set方法
sb.append("}\r\n");
//System.out.println(sb.toString());
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("\tprivate " + sqlType2JavaType(colTypes) + " " + colnames + ";\r\n");
}
sb.append("\r\n");
}
/**
* 功能：生成所有方法
* @param sb
*/
private void processAllMethod(StringBuffer sb) {
for (int i = 0; i < colnames.length; i++) {
if(f_jpa){
if(i==0){
sb.append("\t@Id\r\n");
sb.append("\t@GeneratedValue(strategy = GenerationType.AUTO)\r\n");
sb.append("\tpublic " + sqlType2JavaType(colTypes) + " get" + initcap(colnames) + "(){\r\n");
}else{
sb.append("\tpublic " + sqlType2JavaType(colTypes) + " get" + initcap(colnames) + "(){\r\n");
}
}else{
sb.append("\tpublic " + sqlType2JavaType(colTypes) + " get" + initcap(colnames) + "(){\r\n");
}
sb.append("\t\treturn " + colnames + ";\r\n");
sb.append("\t}\r\n\r\n");
sb.append("\tpublic void set" + initcap(colnames) + "(" + sqlType2JavaType(colTypes) + " " + colnames + "){\r\n");
sb.append("\t\tthis." + colnames + "=" + colnames + ";\r\n");
sb.append("\t}\r\n\r\n");
}
}
/**
* 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")||sqlType.equalsIgnoreCase("INT UNSIGNED")){
//INT UNSIGNED无符号整形
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
* TODO
* @param args
*/
public static void main(String[] args) {
new GenEntityMysql();
}
}