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！");
}
}